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* [PATCH] scsi/NCR5380: Remove in_interrupt() test
@ 2020-12-01  6:46 Finn Thain
  2020-12-01 17:05 ` Sebastian Andrzej Siewior
                   ` (2 more replies)
  0 siblings, 3 replies; 12+ messages in thread
From: Finn Thain @ 2020-12-01  6:46 UTC (permalink / raw)
  To: Michael Schmitz, James E.J. Bottomley, Martin K. Petersen
  Cc: Sebastian Andrzej Siewior, Ahmed S. Darwish, Thomas Gleixner,
	linux-scsi, linux-kernel

The in_interrupt() macro is deprecated. Also, it's usage in
NCR5380_poll_politely2() has long been redundant.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Ahmed S. Darwish <a.darwish@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201126132952.2287996-1-bigeasy@linutronix.de
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/scsi/NCR5380.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index 462d911a89f2..6972e7ceb81a 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -223,7 +223,10 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
 		cpu_relax();
 	} while (n--);
 
-	if (irqs_disabled() || in_interrupt())
+	/* Sleeping is not allowed when in atomic or interrupt contexts.
+	 * Callers in such contexts always disable local irqs.
+	 */
+	if (irqs_disabled())
 		return -ETIMEDOUT;
 
 	/* Repeatedly sleep for 1 ms until deadline */
-- 
2.26.2


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH] scsi/NCR5380: Remove in_interrupt() test
  2020-12-01  6:46 [PATCH] scsi/NCR5380: Remove in_interrupt() test Finn Thain
@ 2020-12-01 17:05 ` Sebastian Andrzej Siewior
  2020-12-03 23:08   ` Finn Thain
  2020-12-01 18:01 ` Michael Schmitz
  2020-12-04 15:32 ` [PATCH v2] scsi: NCR5380: Remove context check Ahmed S. Darwish
  2 siblings, 1 reply; 12+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-12-01 17:05 UTC (permalink / raw)
  To: Finn Thain
  Cc: Michael Schmitz, James E.J. Bottomley, Martin K. Petersen,
	Ahmed S. Darwish, Thomas Gleixner, linux-scsi, linux-kernel

On 2020-12-01 17:46:36 [+1100], Finn Thain wrote:
> The in_interrupt() macro is deprecated. Also, it's usage in
> NCR5380_poll_politely2() has long been redundant.

So you rely on the assumption that interrupts are always disabled. Hmmm.
You complained about the additional argument and that things may get
wrong with it.
Now that I look at it, I realize that hostdata->poll_loops is used for
the initial poll and the `wait' argument is only used for sleeping. What
about it gets redefined to 0 if sleeping is not possible and != 0 if
sleeping is requested. This results in a few callers passing 0 instead
of HZ (or so) which should make things more obvious.

There is however do_abort(, HZ) and abort does internally "wait * 10" so
it matches the old value.
 
--------------->8------------------

From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
Subject: [PATCH] scsi: NCR5380: Remove in_interrupt() usage.

NCR5380_poll_politely2() uses in_interrupt() to check if it is safe to
sleep.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated, or the context be explicitly conveyed in an
argument passed by the caller.

Below is a context analysis of NCR5380_poll_politely2() uppermost
callers:

  - NCR5380_maybe_reset_bus(), task, invoked during device probe.
    -> NCR5380_poll_politely()
    -> do_abort()

  - NCR5380_select(), task, but can only sleep in the "release, then
    re-acquire" regions of the spinlock held by its caller.
    Sleeping invocations (lock released):
    -> NCR5380_poll_politely2()

    Atomic invocations (lock acquired):
    -> NCR5380_reselect()
       -> NCR5380_poll_politely()
       -> do_abort()
       -> NCR5380_transfer_pio()

  - NCR5380_intr(), interrupt handler
    -> NCR5380_dma_complete()
       -> NCR5380_transfer_pio()
	  -> NCR5380_poll_politely()
    -> NCR5380_reselect() (see above)

  - NCR5380_information_transfer(), task, but can only sleep in the
    "release, then re-acquire" regions of the caller-held spinlock.
    Sleeping invocations (lock released):
      - NCR5380_transfer_pio() -> NCR5380_poll_politely()
      - NCR5380_poll_politely()

    Atomic invocations (lock acquired):
      - NCR5380_transfer_dma()
	-> NCR5380_dma_recv_setup()
           => generic_NCR5380_precv() -> NCR5380_poll_politely()
	   => macscsi_pread() -> NCR5380_poll_politely()

	-> NCR5380_dma_send_setup()
 	   => generic_NCR5380_psend -> NCR5380_poll_politely2()
	   => macscsi_pwrite() -> NCR5380_poll_politely()

	-> NCR5380_poll_politely2()
        -> NCR5380_dma_complete()
           -> NCR5380_transfer_pio()
	      -> NCR5380_poll_politely()
      - NCR5380_transfer_pio() -> NCR5380_poll_politely

  - NCR5380_reselect(), atomic, always called with hostdata spinlock
    held.

Use 0 in NCR5380_poll_politely2() delay argument if sleeping is not
possible. Otherwise pass the requested time out in jiffies.

For the mixed ones, trickle-down context from upper layers.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
[bigeasy: remove the bool, make decision based on `wait' ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Finn Thain <fthain@telegraphics.com.au>
Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: <linux-m68k@lists.linux-m68k.org>
---
 drivers/scsi/NCR5380.c   | 74 ++++++++++++++++++++++------------------
 drivers/scsi/NCR5380.h   |  4 ++-
 drivers/scsi/g_NCR5380.c | 12 +++----
 drivers/scsi/mac_scsi.c  | 10 +++---
 4 files changed, 54 insertions(+), 46 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index d597d7493a627..7b0606d8f529a 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -132,7 +132,7 @@
 static unsigned int disconnect_mask = ~0;
 module_param(disconnect_mask, int, 0444);
 
-static int do_abort(struct Scsi_Host *);
+static int do_abort(struct Scsi_Host *, unsigned long);
 static void do_reset(struct Scsi_Host *);
 static void bus_reset_cleanup(struct Scsi_Host *);
 
@@ -197,7 +197,7 @@ static inline void set_resid_from_SCp(struct scsi_cmnd *cmd)
  * @reg2: Second 5380 register to poll
  * @bit2: Second bitmask to check
  * @val2: Second expected value
- * @wait: Time-out in jiffies
+ * @wait: Sleep time-out in jiffies, 0 if sleeping is not allowed
  *
  * Polls the chip in a reasonably efficient manner waiting for an
  * event to occur. After a short quick poll we begin to yield the CPU
@@ -223,7 +223,7 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
 		cpu_relax();
 	} while (n--);
 
-	if (irqs_disabled() || in_interrupt())
+	if (!wait)
 		return -ETIMEDOUT;
 
 	/* Repeatedly sleep for 1 ms until deadline */
@@ -486,7 +486,7 @@ static int NCR5380_maybe_reset_bus(struct Scsi_Host *instance)
 			break;
 		case 2:
 			shost_printk(KERN_ERR, instance, "bus busy, attempting abort\n");
-			do_abort(instance);
+			do_abort(instance, HZ);
 			break;
 		case 4:
 			shost_printk(KERN_ERR, instance, "bus busy, attempting reset\n");
@@ -822,7 +822,7 @@ static void NCR5380_dma_complete(struct Scsi_Host *instance)
 			if (toPIO > 0) {
 				dsprintk(NDEBUG_DMA, instance,
 				         "Doing %d byte PIO to 0x%p\n", cnt, *data);
-				NCR5380_transfer_pio(instance, &p, &cnt, data);
+				NCR5380_transfer_pio(instance, &p, &cnt, data, 0);
 				*count -= toPIO - cnt;
 			}
 		}
@@ -1189,7 +1189,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 		goto out;
 	}
 	if (!hostdata->selecting) {
-		do_abort(instance);
+		do_abort(instance, 0);
 		return false;
 	}
 
@@ -1200,7 +1200,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 	len = 1;
 	data = tmp;
 	phase = PHASE_MSGOUT;
-	NCR5380_transfer_pio(instance, &phase, &len, &data);
+	NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 	if (len) {
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		cmd->result = DID_ERROR << 16;
@@ -1238,7 +1238,8 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
  *
  * Inputs : instance - instance of driver, *phase - pointer to
  * what phase is expected, *count - pointer to number of
- * bytes to transfer, **data - pointer to data pointer.
+ * bytes to transfer, **data - pointer to data pointer,
+ * wait - sleep time-out in jiffies, 0 if sleeping is now allowed.
  *
  * Returns : -1 when different phase is entered without transferring
  * maximum number of bytes, 0 if all bytes are transferred or exit
@@ -1257,7 +1258,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 
 static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 				unsigned char *phase, int *count,
-				unsigned char **data)
+				unsigned char **data, unsigned long wait)
 {
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 	unsigned char p = *phase, tmp;
@@ -1278,7 +1279,8 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 		 * valid
 		 */
 
-		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, HZ) < 0)
+		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+					  wait) < 0)
 			break;
 
 		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ asserted\n");
@@ -1324,7 +1326,7 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 		}
 
 		if (NCR5380_poll_politely(hostdata,
-		                          STATUS_REG, SR_REQ, 0, 5 * HZ) < 0)
+		                          STATUS_REG, SR_REQ, 0, wait * 5) < 0)
 			break;
 
 		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ negated, handshake complete\n");
@@ -1399,11 +1401,12 @@ static void do_reset(struct Scsi_Host *instance)
  * do_abort - abort the currently established nexus by going to
  * MESSAGE OUT phase and sending an ABORT message.
  * @instance: relevant scsi host instance
+ * @wait: Sleep time-out in jiffies.
  *
  * Returns 0 on success, negative error code on failure.
  */
 
-static int do_abort(struct Scsi_Host *instance)
+static int do_abort(struct Scsi_Host *instance, unsigned long wait)
 {
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 	unsigned char *msgptr, phase, tmp;
@@ -1423,7 +1426,8 @@ static int do_abort(struct Scsi_Host *instance)
 	 * the target sees, so we just handshake.
 	 */
 
-	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, 10 * HZ);
+	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+				   wait * 10);
 	if (rc < 0)
 		goto out;
 
@@ -1434,7 +1438,8 @@ static int do_abort(struct Scsi_Host *instance)
 	if (tmp != PHASE_MSGOUT) {
 		NCR5380_write(INITIATOR_COMMAND_REG,
 		              ICR_BASE | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
-		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0, 3 * HZ);
+		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0,
+					   wait * 3);
 		if (rc < 0)
 			goto out;
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
@@ -1444,7 +1449,7 @@ static int do_abort(struct Scsi_Host *instance)
 	msgptr = &tmp;
 	len = 1;
 	phase = PHASE_MSGOUT;
-	NCR5380_transfer_pio(instance, &phase, &len, &msgptr);
+	NCR5380_transfer_pio(instance, &phase, &len, &msgptr, wait);
 	if (len)
 		rc = -ENXIO;
 
@@ -1623,12 +1628,12 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 			 */
 
 			if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
-			                          BASR_DRQ, BASR_DRQ, HZ) < 0) {
+			                          BASR_DRQ, BASR_DRQ, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA read: DRQ timeout\n");
 			}
 			if (NCR5380_poll_politely(hostdata, STATUS_REG,
-			                          SR_REQ, 0, HZ) < 0) {
+			                          SR_REQ, 0, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA read: !REQ timeout\n");
 			}
@@ -1640,7 +1645,7 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 			 */
 			if (NCR5380_poll_politely2(hostdata,
 			     BUS_AND_STATUS_REG, BASR_DRQ, BASR_DRQ,
-			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, HZ) < 0) {
+			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA write: DRQ and phase timeout\n");
 			}
@@ -1737,7 +1742,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 #if (NDEBUG & NDEBUG_NO_DATAOUT)
 				shost_printk(KERN_DEBUG, instance, "NDEBUG_NO_DATAOUT set, attempted DATAOUT aborted\n");
 				sink = 1;
-				do_abort(instance);
+				do_abort(instance, 0);
 				cmd->result = DID_ERROR << 16;
 				complete_cmd(instance, cmd);
 				hostdata->connected = NULL;
@@ -1793,7 +1798,8 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 							   NCR5380_PIO_CHUNK_SIZE);
 					len = transfersize;
 					NCR5380_transfer_pio(instance, &phase, &len,
-					                     (unsigned char **)&cmd->SCp.ptr);
+					                     (unsigned char **)&cmd->SCp.ptr,
+							     0);
 					cmd->SCp.this_residual -= transfersize - len;
 				}
 #ifdef CONFIG_SUN3
@@ -1804,7 +1810,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 			case PHASE_MSGIN:
 				len = 1;
 				data = &tmp;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				cmd->SCp.Message = tmp;
 
 				switch (tmp) {
@@ -1910,7 +1916,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 					len = 2;
 					data = extended_msg + 1;
 					phase = PHASE_MSGIN;
-					NCR5380_transfer_pio(instance, &phase, &len, &data);
+					NCR5380_transfer_pio(instance, &phase, &len, &data, HZ);
 					dsprintk(NDEBUG_EXTENDED, instance, "length %d, code 0x%02x\n",
 					         (int)extended_msg[1],
 					         (int)extended_msg[2]);
@@ -1923,7 +1929,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 						data = extended_msg + 3;
 						phase = PHASE_MSGIN;
 
-						NCR5380_transfer_pio(instance, &phase, &len, &data);
+						NCR5380_transfer_pio(instance, &phase, &len, &data, HZ);
 						dsprintk(NDEBUG_EXTENDED, instance, "message received, residual %d\n",
 						         len);
 
@@ -1970,7 +1976,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				len = 1;
 				data = &msgout;
 				hostdata->last_message = msgout;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				if (msgout == ABORT) {
 					hostdata->connected = NULL;
 					hostdata->busy[scmd_id(cmd)] &= ~(1 << cmd->device->lun);
@@ -1988,12 +1994,12 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				 * PSEUDO-DMA architecture we should probably
 				 * use the dma transfer function.
 				 */
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				break;
 			case PHASE_STATIN:
 				len = 1;
 				data = &tmp;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				cmd->SCp.Status = tmp;
 				break;
 			default:
@@ -2052,7 +2058,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 
 	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_BSY);
 	if (NCR5380_poll_politely(hostdata,
-	                          STATUS_REG, SR_SEL, 0, 2 * HZ) < 0) {
+	                          STATUS_REG, SR_SEL, 0, 0) < 0) {
 		shost_printk(KERN_ERR, instance, "reselect: !SEL timeout\n");
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		return;
@@ -2064,12 +2070,12 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 	 */
 
 	if (NCR5380_poll_politely(hostdata,
-	                          STATUS_REG, SR_REQ, SR_REQ, 2 * HZ) < 0) {
+	                          STATUS_REG, SR_REQ, SR_REQ, 0) < 0) {
 		if ((NCR5380_read(STATUS_REG) & (SR_BSY | SR_SEL)) == 0)
 			/* BUS FREE phase */
 			return;
 		shost_printk(KERN_ERR, instance, "reselect: REQ timeout\n");
-		do_abort(instance);
+		do_abort(instance, 0);
 		return;
 	}
 
@@ -2085,10 +2091,10 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		unsigned char *data = msg;
 		unsigned char phase = PHASE_MSGIN;
 
-		NCR5380_transfer_pio(instance, &phase, &len, &data);
+		NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 
 		if (len) {
-			do_abort(instance);
+			do_abort(instance, 0);
 			return;
 		}
 	}
@@ -2098,7 +2104,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		shost_printk(KERN_ERR, instance, "expecting IDENTIFY message, got ");
 		spi_print_msg(msg);
 		printk("\n");
-		do_abort(instance);
+		do_abort(instance, 0);
 		return;
 	}
 	lun = msg[0] & 0x07;
@@ -2138,7 +2144,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		 * Since we have an established nexus that we can't do anything
 		 * with, we must abort it.
 		 */
-		if (do_abort(instance) == 0)
+		if (do_abort(instance, 0) == 0)
 			hostdata->busy[target] &= ~(1 << lun);
 		return;
 	}
@@ -2285,7 +2291,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
 		dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
 		hostdata->connected = NULL;
 		hostdata->dma_len = 0;
-		if (do_abort(instance) < 0) {
+		if (do_abort(instance, 0) < 0) {
 			set_host_byte(cmd, DID_ERROR);
 			complete_cmd(instance, cmd);
 			result = FAILED;
diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
index 5935fd6d1a058..578983e328d19 100644
--- a/drivers/scsi/NCR5380.h
+++ b/drivers/scsi/NCR5380.h
@@ -277,7 +277,9 @@ static const char *NCR5380_info(struct Scsi_Host *instance);
 static void NCR5380_reselect(struct Scsi_Host *instance);
 static bool NCR5380_select(struct Scsi_Host *, struct scsi_cmnd *);
 static int NCR5380_transfer_dma(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
-static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
+static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase,
+				int *count, unsigned char **data,
+				unsigned long wait);
 static int NCR5380_poll_politely2(struct NCR5380_hostdata *,
                                   unsigned int, u8, u8,
                                   unsigned int, u8, u8, unsigned long);
diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 29e4cdcade720..2df2f38a9b122 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -529,14 +529,14 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
 		if (start == len - 128) {
 			/* Ignore End of DMA interrupt for the final buffer */
 			if (NCR5380_poll_politely(hostdata, hostdata->c400_ctl_status,
-			                          CSR_HOST_BUF_NOT_RDY, 0, HZ / 64) < 0)
+			                          CSR_HOST_BUF_NOT_RDY, 0, 0) < 0)
 				break;
 		} else {
 			if (NCR5380_poll_politely2(hostdata, hostdata->c400_ctl_status,
 			                           CSR_HOST_BUF_NOT_RDY, 0,
 			                           hostdata->c400_ctl_status,
 			                           CSR_GATED_53C80_IRQ,
-			                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
+			                           CSR_GATED_53C80_IRQ, 0) < 0 ||
 			    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY)
 				break;
 		}
@@ -565,7 +565,7 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
 	if (residual == 0 && NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                                           BASR_END_DMA_TRANSFER,
 	                                           BASR_END_DMA_TRANSFER,
-	                                           HZ / 64) < 0)
+						   0) < 0)
 		scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
 		            __func__);
 
@@ -597,7 +597,7 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
 		                           CSR_HOST_BUF_NOT_RDY, 0,
 		                           hostdata->c400_ctl_status,
 		                           CSR_GATED_53C80_IRQ,
-		                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
+		                           CSR_GATED_53C80_IRQ, 0) < 0 ||
 		    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) {
 			/* Both 128 B buffers are in use */
 			if (start >= 128)
@@ -644,13 +644,13 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
 	if (residual == 0) {
 		if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 		                          TCR_LAST_BYTE_SENT, TCR_LAST_BYTE_SENT,
-		                          HZ / 64) < 0)
+					  0) < 0)
 			scmd_printk(KERN_ERR, hostdata->connected,
 			            "%s: Last Byte Sent timeout\n", __func__);
 
 		if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 		                          BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER,
-		                          HZ / 64) < 0)
+					  0) < 0)
 			scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
 			            __func__);
 	}
diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index b5dde9d0d0545..5c808fbc6ce2c 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -285,7 +285,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
-	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
+	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
 		int bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
@@ -304,7 +304,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, HZ / 64) < 0)
+		                           BASR_ACK, 0) < 0)
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
@@ -344,7 +344,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
-	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
+	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
 		int bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
@@ -362,7 +362,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 			                          TCR_LAST_BYTE_SENT,
 			                          TCR_LAST_BYTE_SENT,
-			                          HZ / 64) < 0) {
+			                          0) < 0) {
 				scmd_printk(KERN_ERR, hostdata->connected,
 				            "%s: Last Byte Sent timeout\n", __func__);
 				result = -1;
@@ -372,7 +372,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, HZ / 64) < 0)
+		                           BASR_ACK, 0) < 0)
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
-- 
2.29.2


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH] scsi/NCR5380: Remove in_interrupt() test
  2020-12-01  6:46 [PATCH] scsi/NCR5380: Remove in_interrupt() test Finn Thain
  2020-12-01 17:05 ` Sebastian Andrzej Siewior
@ 2020-12-01 18:01 ` Michael Schmitz
  2020-12-04 15:32 ` [PATCH v2] scsi: NCR5380: Remove context check Ahmed S. Darwish
  2 siblings, 0 replies; 12+ messages in thread
From: Michael Schmitz @ 2020-12-01 18:01 UTC (permalink / raw)
  To: Finn Thain, James E.J. Bottomley, Martin K. Petersen
  Cc: Sebastian Andrzej Siewior, Ahmed S. Darwish, Thomas Gleixner,
	linux-scsi, linux-kernel

Hi Finn,

works fine, thanks!

Tested-By: Michael Schmitz <schmitzmic@gmail.com>


On 1/12/20 7:46 PM, Finn Thain wrote:
> The in_interrupt() macro is deprecated. Also, it's usage in
> NCR5380_poll_politely2() has long been redundant.
>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Ahmed S. Darwish <a.darwish@linutronix.de>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Link: https://lore.kernel.org/r/20201126132952.2287996-1-bigeasy@linutronix.de
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
> ---
>   drivers/scsi/NCR5380.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index 462d911a89f2..6972e7ceb81a 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -223,7 +223,10 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
>   		cpu_relax();
>   	} while (n--);
>   
> -	if (irqs_disabled() || in_interrupt())
> +	/* Sleeping is not allowed when in atomic or interrupt contexts.
> +	 * Callers in such contexts always disable local irqs.
> +	 */
> +	if (irqs_disabled())
>   		return -ETIMEDOUT;
>   
>   	/* Repeatedly sleep for 1 ms until deadline */

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH] scsi/NCR5380: Remove in_interrupt() test
  2020-12-01 17:05 ` Sebastian Andrzej Siewior
@ 2020-12-03 23:08   ` Finn Thain
  2020-12-04  8:38     ` Geert Uytterhoeven
  2020-12-04 16:08     ` Ahmed S. Darwish
  0 siblings, 2 replies; 12+ messages in thread
From: Finn Thain @ 2020-12-03 23:08 UTC (permalink / raw)
  To: Sebastian Andrzej Siewior
  Cc: Michael Schmitz, James E.J. Bottomley, Martin K. Petersen,
	Ahmed S. Darwish, Thomas Gleixner, linux-scsi, linux-kernel

136046n Tue, 1 Dec 2020, Sebastian Andrzej Siewior wrote:

> On 2020-12-01 17:46:36 [+1100], Finn Thain wrote:
> > The in_interrupt() macro is deprecated. Also, it's usage in 
> > NCR5380_poll_politely2() has long been redundant.
> 
> So you rely on the assumption that interrupts are always disabled. Hmmm.
> You complained about the additional argument and that things may get
> wrong with it.
> Now that I look at it, I realize that hostdata->poll_loops is used for
> the initial poll and the `wait' argument is only used for sleeping. What
> about it gets redefined to 0 if sleeping is not possible and != 0 if
> sleeping is requested. 
> This results in a few callers passing 0 instead of HZ (or so) which 
> should make things more obvious.
> 
> There is however do_abort(, HZ) and abort does internally "wait * 10" so
> it matches the old value.
>  

So the argument being passed is not simply "poll interval" in jiffies but 
"poll interval divided by 10"? That's a suprising API to chose (further 
comments below).

> --------------->8------------------
> 
> From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
> Subject: [PATCH] scsi: NCR5380: Remove in_interrupt() usage.
> 
> NCR5380_poll_politely2() uses in_interrupt() to check if it is safe to
> sleep.
> 
> The usage of in_interrupt() in drivers is phased out and Linus clearly
> requested that code which changes behaviour depending on context should
> either be separated, or the context be explicitly conveyed in an
> argument passed by the caller.
> 
> Below is a context analysis of NCR5380_poll_politely2() uppermost
> callers:
> 
>   - NCR5380_maybe_reset_bus(), task, invoked during device probe.
>     -> NCR5380_poll_politely()
>     -> do_abort()
> 
>   - NCR5380_select(), task, but can only sleep in the "release, then
>     re-acquire" regions of the spinlock held by its caller.
>     Sleeping invocations (lock released):
>     -> NCR5380_poll_politely2()
> 
>     Atomic invocations (lock acquired):
>     -> NCR5380_reselect()
>        -> NCR5380_poll_politely()
>        -> do_abort()
>        -> NCR5380_transfer_pio()
> 
>   - NCR5380_intr(), interrupt handler
>     -> NCR5380_dma_complete()
>        -> NCR5380_transfer_pio()
> 	  -> NCR5380_poll_politely()
>     -> NCR5380_reselect() (see above)
> 
>   - NCR5380_information_transfer(), task, but can only sleep in the
>     "release, then re-acquire" regions of the caller-held spinlock.
>     Sleeping invocations (lock released):
>       - NCR5380_transfer_pio() -> NCR5380_poll_politely()
>       - NCR5380_poll_politely()
> 
>     Atomic invocations (lock acquired):
>       - NCR5380_transfer_dma()
> 	-> NCR5380_dma_recv_setup()
>            => generic_NCR5380_precv() -> NCR5380_poll_politely()
> 	   => macscsi_pread() -> NCR5380_poll_politely()
> 
> 	-> NCR5380_dma_send_setup()
>  	   => generic_NCR5380_psend -> NCR5380_poll_politely2()
> 	   => macscsi_pwrite() -> NCR5380_poll_politely()
> 
> 	-> NCR5380_poll_politely2()
>         -> NCR5380_dma_complete()
>            -> NCR5380_transfer_pio()
> 	      -> NCR5380_poll_politely()
>       - NCR5380_transfer_pio() -> NCR5380_poll_politely
> 
>   - NCR5380_reselect(), atomic, always called with hostdata spinlock
>     held.
> 
> Use 0 in NCR5380_poll_politely2() delay argument if sleeping is not
> possible. Otherwise pass the requested time out in jiffies.
> 
> For the mixed ones, trickle-down context from upper layers.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> [bigeasy: remove the bool, make decision based on `wait' ]
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Finn Thain <fthain@telegraphics.com.au>
> Cc: Michael Schmitz <schmitzmic@gmail.com>
> Cc: <linux-m68k@lists.linux-m68k.org>
> ---
>  drivers/scsi/NCR5380.c   | 74 ++++++++++++++++++++++------------------
>  drivers/scsi/NCR5380.h   |  4 ++-
>  drivers/scsi/g_NCR5380.c | 12 +++----
>  drivers/scsi/mac_scsi.c  | 10 +++---
>  4 files changed, 54 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index d597d7493a627..7b0606d8f529a 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -132,7 +132,7 @@
>  static unsigned int disconnect_mask = ~0;
>  module_param(disconnect_mask, int, 0444);
>  
> -static int do_abort(struct Scsi_Host *);
> +static int do_abort(struct Scsi_Host *, unsigned long);
>  static void do_reset(struct Scsi_Host *);
>  static void bus_reset_cleanup(struct Scsi_Host *);
>  
> @@ -197,7 +197,7 @@ static inline void set_resid_from_SCp(struct scsi_cmnd *cmd)
>   * @reg2: Second 5380 register to poll
>   * @bit2: Second bitmask to check
>   * @val2: Second expected value
> - * @wait: Time-out in jiffies
> + * @wait: Sleep time-out in jiffies, 0 if sleeping is not allowed
>   *
>   * Polls the chip in a reasonably efficient manner waiting for an
>   * event to occur. After a short quick poll we begin to yield the CPU
> @@ -223,7 +223,7 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
>  		cpu_relax();
>  	} while (n--);
>  
> -	if (irqs_disabled() || in_interrupt())
> +	if (!wait)
>  		return -ETIMEDOUT;
>  
>  	/* Repeatedly sleep for 1 ms until deadline */
> @@ -486,7 +486,7 @@ static int NCR5380_maybe_reset_bus(struct Scsi_Host *instance)
>  			break;
>  		case 2:
>  			shost_printk(KERN_ERR, instance, "bus busy, attempting abort\n");
> -			do_abort(instance);
> +			do_abort(instance, HZ);
>  			break;
>  		case 4:
>  			shost_printk(KERN_ERR, instance, "bus busy, attempting reset\n");
> @@ -822,7 +822,7 @@ static void NCR5380_dma_complete(struct Scsi_Host *instance)
>  			if (toPIO > 0) {
>  				dsprintk(NDEBUG_DMA, instance,
>  				         "Doing %d byte PIO to 0x%p\n", cnt, *data);
> -				NCR5380_transfer_pio(instance, &p, &cnt, data);
> +				NCR5380_transfer_pio(instance, &p, &cnt, data, 0);
>  				*count -= toPIO - cnt;
>  			}
>  		}
> @@ -1189,7 +1189,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>  		goto out;
>  	}
>  	if (!hostdata->selecting) {
> -		do_abort(instance);
> +		do_abort(instance, 0);
>  		return false;
>  	}
>  
> @@ -1200,7 +1200,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>  	len = 1;
>  	data = tmp;
>  	phase = PHASE_MSGOUT;
> -	NCR5380_transfer_pio(instance, &phase, &len, &data);
> +	NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
>  	if (len) {
>  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
>  		cmd->result = DID_ERROR << 16;
> @@ -1238,7 +1238,8 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>   *
>   * Inputs : instance - instance of driver, *phase - pointer to
>   * what phase is expected, *count - pointer to number of
> - * bytes to transfer, **data - pointer to data pointer.
> + * bytes to transfer, **data - pointer to data pointer,
> + * wait - sleep time-out in jiffies, 0 if sleeping is now allowed.
>   *
>   * Returns : -1 when different phase is entered without transferring
>   * maximum number of bytes, 0 if all bytes are transferred or exit
> @@ -1257,7 +1258,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
>  
>  static int NCR5380_transfer_pio(struct Scsi_Host *instance,
>  				unsigned char *phase, int *count,
> -				unsigned char **data)
> +				unsigned char **data, unsigned long wait)
>  {
>  	struct NCR5380_hostdata *hostdata = shost_priv(instance);
>  	unsigned char p = *phase, tmp;
> @@ -1278,7 +1279,8 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
>  		 * valid
>  		 */
>  
> -		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, HZ) < 0)
> +		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
> +					  wait) < 0)
>  			break;
>  
>  		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ asserted\n");
> @@ -1324,7 +1326,7 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
>  		}
>  
>  		if (NCR5380_poll_politely(hostdata,
> -		                          STATUS_REG, SR_REQ, 0, 5 * HZ) < 0)
> +		                          STATUS_REG, SR_REQ, 0, wait * 5) < 0)

Apparently 'wait' has two possible values, 0 or HZ? That seems like 
another unintuitive API... perhaps you might want that if different 
callers had different values for HZ (they don't). Because this API is 
unintuitive, it would invite even more mistakes than just adding the 
'can_sleep' argument and would need more documentation.

Anyway, I think what you were trying to achieve was a timeout value like 
this:

              if (NCR5380_poll_politely(hostdata,
-                                       STATUS_REG, SR_REQ, 0, 5 * HZ) < 0)
+                                       STATUS_REG, SR_REQ, 0, 5 * HZ * can_sleep) < 0)

I can see some some merit in this (discussed below).

>  
>  		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ negated, handshake complete\n");
> @@ -1399,11 +1401,12 @@ static void do_reset(struct Scsi_Host *instance)
>   * do_abort - abort the currently established nexus by going to
>   * MESSAGE OUT phase and sending an ABORT message.
>   * @instance: relevant scsi host instance
> + * @wait: Sleep time-out in jiffies.
>   *
>   * Returns 0 on success, negative error code on failure.
>   */
>  
> -static int do_abort(struct Scsi_Host *instance)
> +static int do_abort(struct Scsi_Host *instance, unsigned long wait)
>  {
>  	struct NCR5380_hostdata *hostdata = shost_priv(instance);
>  	unsigned char *msgptr, phase, tmp;
> @@ -1423,7 +1426,8 @@ static int do_abort(struct Scsi_Host *instance)
>  	 * the target sees, so we just handshake.
>  	 */
>  
> -	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, 10 * HZ);
> +	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
> +				   wait * 10);
>  	if (rc < 0)
>  		goto out;
>  
> @@ -1434,7 +1438,8 @@ static int do_abort(struct Scsi_Host *instance)
>  	if (tmp != PHASE_MSGOUT) {
>  		NCR5380_write(INITIATOR_COMMAND_REG,
>  		              ICR_BASE | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
> -		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0, 3 * HZ);
> +		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0,
> +					   wait * 3);
>  		if (rc < 0)
>  			goto out;
>  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
> @@ -1444,7 +1449,7 @@ static int do_abort(struct Scsi_Host *instance)
>  	msgptr = &tmp;
>  	len = 1;
>  	phase = PHASE_MSGOUT;
> -	NCR5380_transfer_pio(instance, &phase, &len, &msgptr);
> +	NCR5380_transfer_pio(instance, &phase, &len, &msgptr, wait);
>  	if (len)
>  		rc = -ENXIO;
>  
> @@ -1623,12 +1628,12 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
>  			 */
>  
>  			if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
> -			                          BASR_DRQ, BASR_DRQ, HZ) < 0) {
> +			                          BASR_DRQ, BASR_DRQ, 0) < 0) {
>  				result = -1;
>  				shost_printk(KERN_ERR, instance, "PDMA read: DRQ timeout\n");
>  			}
>  			if (NCR5380_poll_politely(hostdata, STATUS_REG,
> -			                          SR_REQ, 0, HZ) < 0) {
> +			                          SR_REQ, 0, 0) < 0) {
>  				result = -1;
>  				shost_printk(KERN_ERR, instance, "PDMA read: !REQ timeout\n");
>  			}
> @@ -1640,7 +1645,7 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
>  			 */
>  			if (NCR5380_poll_politely2(hostdata,
>  			     BUS_AND_STATUS_REG, BASR_DRQ, BASR_DRQ,
> -			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, HZ) < 0) {
> +			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, 0) < 0) {
>  				result = -1;
>  				shost_printk(KERN_ERR, instance, "PDMA write: DRQ and phase timeout\n");
>  			}
> @@ -1737,7 +1742,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  #if (NDEBUG & NDEBUG_NO_DATAOUT)
>  				shost_printk(KERN_DEBUG, instance, "NDEBUG_NO_DATAOUT set, attempted DATAOUT aborted\n");
>  				sink = 1;
> -				do_abort(instance);
> +				do_abort(instance, 0);
>  				cmd->result = DID_ERROR << 16;
>  				complete_cmd(instance, cmd);
>  				hostdata->connected = NULL;
> @@ -1793,7 +1798,8 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  							   NCR5380_PIO_CHUNK_SIZE);
>  					len = transfersize;
>  					NCR5380_transfer_pio(instance, &phase, &len,
> -					                     (unsigned char **)&cmd->SCp.ptr);
> +					                     (unsigned char **)&cmd->SCp.ptr,
> +							     0);
>  					cmd->SCp.this_residual -= transfersize - len;
>  				}
>  #ifdef CONFIG_SUN3
> @@ -1804,7 +1810,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  			case PHASE_MSGIN:
>  				len = 1;
>  				data = &tmp;
> -				NCR5380_transfer_pio(instance, &phase, &len, &data);
> +				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
>  				cmd->SCp.Message = tmp;
>  
>  				switch (tmp) {
> @@ -1910,7 +1916,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  					len = 2;
>  					data = extended_msg + 1;
>  					phase = PHASE_MSGIN;
> -					NCR5380_transfer_pio(instance, &phase, &len, &data);
> +					NCR5380_transfer_pio(instance, &phase, &len, &data, HZ);
>  					dsprintk(NDEBUG_EXTENDED, instance, "length %d, code 0x%02x\n",
>  					         (int)extended_msg[1],
>  					         (int)extended_msg[2]);
> @@ -1923,7 +1929,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  						data = extended_msg + 3;
>  						phase = PHASE_MSGIN;
>  
> -						NCR5380_transfer_pio(instance, &phase, &len, &data);
> +						NCR5380_transfer_pio(instance, &phase, &len, &data, HZ);
>  						dsprintk(NDEBUG_EXTENDED, instance, "message received, residual %d\n",
>  						         len);
>  
> @@ -1970,7 +1976,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  				len = 1;
>  				data = &msgout;
>  				hostdata->last_message = msgout;
> -				NCR5380_transfer_pio(instance, &phase, &len, &data);
> +				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
>  				if (msgout == ABORT) {
>  					hostdata->connected = NULL;
>  					hostdata->busy[scmd_id(cmd)] &= ~(1 << cmd->device->lun);
> @@ -1988,12 +1994,12 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
>  				 * PSEUDO-DMA architecture we should probably
>  				 * use the dma transfer function.
>  				 */
> -				NCR5380_transfer_pio(instance, &phase, &len, &data);
> +				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
>  				break;
>  			case PHASE_STATIN:
>  				len = 1;
>  				data = &tmp;
> -				NCR5380_transfer_pio(instance, &phase, &len, &data);
> +				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
>  				cmd->SCp.Status = tmp;
>  				break;
>  			default:
> @@ -2052,7 +2058,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
>  
>  	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_BSY);
>  	if (NCR5380_poll_politely(hostdata,
> -	                          STATUS_REG, SR_SEL, 0, 2 * HZ) < 0) {
> +	                          STATUS_REG, SR_SEL, 0, 0) < 0) {
>  		shost_printk(KERN_ERR, instance, "reselect: !SEL timeout\n");
>  		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
>  		return;
> @@ -2064,12 +2070,12 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
>  	 */
>  
>  	if (NCR5380_poll_politely(hostdata,
> -	                          STATUS_REG, SR_REQ, SR_REQ, 2 * HZ) < 0) {
> +	                          STATUS_REG, SR_REQ, SR_REQ, 0) < 0) {
>  		if ((NCR5380_read(STATUS_REG) & (SR_BSY | SR_SEL)) == 0)
>  			/* BUS FREE phase */
>  			return;
>  		shost_printk(KERN_ERR, instance, "reselect: REQ timeout\n");
> -		do_abort(instance);
> +		do_abort(instance, 0);
>  		return;
>  	}
>  
> @@ -2085,10 +2091,10 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
>  		unsigned char *data = msg;
>  		unsigned char phase = PHASE_MSGIN;
>  
> -		NCR5380_transfer_pio(instance, &phase, &len, &data);
> +		NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
>  
>  		if (len) {
> -			do_abort(instance);
> +			do_abort(instance, 0);
>  			return;
>  		}
>  	}
> @@ -2098,7 +2104,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
>  		shost_printk(KERN_ERR, instance, "expecting IDENTIFY message, got ");
>  		spi_print_msg(msg);
>  		printk("\n");
> -		do_abort(instance);
> +		do_abort(instance, 0);
>  		return;
>  	}
>  	lun = msg[0] & 0x07;
> @@ -2138,7 +2144,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
>  		 * Since we have an established nexus that we can't do anything
>  		 * with, we must abort it.
>  		 */
> -		if (do_abort(instance) == 0)
> +		if (do_abort(instance, 0) == 0)
>  			hostdata->busy[target] &= ~(1 << lun);
>  		return;
>  	}
> @@ -2285,7 +2291,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
>  		dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
>  		hostdata->connected = NULL;
>  		hostdata->dma_len = 0;
> -		if (do_abort(instance) < 0) {
> +		if (do_abort(instance, 0) < 0) {
>  			set_host_byte(cmd, DID_ERROR);
>  			complete_cmd(instance, cmd);
>  			result = FAILED;
> diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
> index 5935fd6d1a058..578983e328d19 100644
> --- a/drivers/scsi/NCR5380.h
> +++ b/drivers/scsi/NCR5380.h
> @@ -277,7 +277,9 @@ static const char *NCR5380_info(struct Scsi_Host *instance);
>  static void NCR5380_reselect(struct Scsi_Host *instance);
>  static bool NCR5380_select(struct Scsi_Host *, struct scsi_cmnd *);
>  static int NCR5380_transfer_dma(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
> -static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
> +static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase,
> +				int *count, unsigned char **data,
> +				unsigned long wait);
>  static int NCR5380_poll_politely2(struct NCR5380_hostdata *,
>                                    unsigned int, u8, u8,
>                                    unsigned int, u8, u8, unsigned long);
> diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
> index 29e4cdcade720..2df2f38a9b122 100644
> --- a/drivers/scsi/g_NCR5380.c
> +++ b/drivers/scsi/g_NCR5380.c
> @@ -529,14 +529,14 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
>  		if (start == len - 128) {
>  			/* Ignore End of DMA interrupt for the final buffer */
>  			if (NCR5380_poll_politely(hostdata, hostdata->c400_ctl_status,
> -			                          CSR_HOST_BUF_NOT_RDY, 0, HZ / 64) < 0)
> +			                          CSR_HOST_BUF_NOT_RDY, 0, 0) < 0)

You've put your finger on a known problem with certain 
NCR5380_poll_politely() call sites. That is, the nominal timeout, HZ / 64, 
is meaningless because it is ignored in atomic context. So you may as well 
specify 0 jiffies at these call sites. (There will be a 1 jiffy timeout 
applied regardless.)

BTW, a jiffy is an unknown quantity here. This driver has tradionally 
assumed that 1 jiffy == 10 ms and this is always true on m68k. That 
assumption is something that we probably need to address as part of the 
timekeeping modernization for m68k.

>  				break;
>  		} else {
>  			if (NCR5380_poll_politely2(hostdata, hostdata->c400_ctl_status,
>  			                           CSR_HOST_BUF_NOT_RDY, 0,
>  			                           hostdata->c400_ctl_status,
>  			                           CSR_GATED_53C80_IRQ,
> -			                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
> +			                           CSR_GATED_53C80_IRQ, 0) < 0 ||
>  			    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY)
>  				break;
>  		}
> @@ -565,7 +565,7 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
>  	if (residual == 0 && NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
>  	                                           BASR_END_DMA_TRANSFER,
>  	                                           BASR_END_DMA_TRANSFER,
> -	                                           HZ / 64) < 0)
> +						   0) < 0)
>  		scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
>  		            __func__);
>  
> @@ -597,7 +597,7 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
>  		                           CSR_HOST_BUF_NOT_RDY, 0,
>  		                           hostdata->c400_ctl_status,
>  		                           CSR_GATED_53C80_IRQ,
> -		                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
> +		                           CSR_GATED_53C80_IRQ, 0) < 0 ||
>  		    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) {
>  			/* Both 128 B buffers are in use */
>  			if (start >= 128)
> @@ -644,13 +644,13 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
>  	if (residual == 0) {
>  		if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
>  		                          TCR_LAST_BYTE_SENT, TCR_LAST_BYTE_SENT,
> -		                          HZ / 64) < 0)
> +					  0) < 0)
>  			scmd_printk(KERN_ERR, hostdata->connected,
>  			            "%s: Last Byte Sent timeout\n", __func__);
>  
>  		if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
>  		                          BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER,
> -		                          HZ / 64) < 0)
> +					  0) < 0)
>  			scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
>  			            __func__);
>  	}
> diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
> index b5dde9d0d0545..5c808fbc6ce2c 100644
> --- a/drivers/scsi/mac_scsi.c
> +++ b/drivers/scsi/mac_scsi.c
> @@ -285,7 +285,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
>  
>  	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
>  	                              BASR_DRQ | BASR_PHASE_MATCH,
> -	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
> +	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
>  		int bytes;
>  
>  		if (macintosh_config->ident == MAC_MODEL_IIFX)
> @@ -304,7 +304,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
>  
>  		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
>  		                           BUS_AND_STATUS_REG, BASR_ACK,
> -		                           BASR_ACK, HZ / 64) < 0)
> +		                           BASR_ACK, 0) < 0)
>  			scmd_printk(KERN_DEBUG, hostdata->connected,
>  			            "%s: !REQ and !ACK\n", __func__);
>  		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
> @@ -344,7 +344,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
>  
>  	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
>  	                              BASR_DRQ | BASR_PHASE_MATCH,
> -	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
> +	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
>  		int bytes;
>  
>  		if (macintosh_config->ident == MAC_MODEL_IIFX)
> @@ -362,7 +362,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
>  			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
>  			                          TCR_LAST_BYTE_SENT,
>  			                          TCR_LAST_BYTE_SENT,
> -			                          HZ / 64) < 0) {
> +			                          0) < 0) {
>  				scmd_printk(KERN_ERR, hostdata->connected,
>  				            "%s: Last Byte Sent timeout\n", __func__);
>  				result = -1;
> @@ -372,7 +372,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
>  
>  		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
>  		                           BUS_AND_STATUS_REG, BASR_ACK,
> -		                           BASR_ACK, HZ / 64) < 0)
> +		                           BASR_ACK, 0) < 0)
>  			scmd_printk(KERN_DEBUG, hostdata->connected,
>  			            "%s: !REQ and !ACK\n", __func__);
>  		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
> 

The style change itself (i.e. replacing irqs_disabled() with a parameter 
to accomplish the same thing) is not worth the churn, IMO.

However, I can see the value in your approach, i.e. passing a zero timeout 
to NCR5380_poll_politely() whenever that argument is unused. And I agree 
that this could then be used to inhibit sleeping, rather than testing 
irqs_disabled().

So if you really don't like irqs_disabled(), perhaps you can just keep the 
better parts of your two attempts, i.e. passing 0 to 
NCR5380_poll_politely() where appropriate and facilitating that by adding 
a new can_sleep parameter to do_abort() and NCR5380_transfer_pio(), as in,

@@ -1253,7 +1254,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 
 static int NCR5380_transfer_pio(struct Scsi_Host *instance,
                                unsigned char *phase, int *count,
-                               unsigned char **data)
+                               unsigned char **data, unsigned int can_sleep)
 {
        struct NCR5380_hostdata *hostdata = shost_priv(instance);
        unsigned char p = *phase, tmp;

@@ -1395,11 +1396,12 @@ static void do_reset(struct Scsi_Host *instance)
  * do_abort - abort the currently established nexus by going to
  * MESSAGE OUT phase and sending an ABORT message.
  * @instance: relevant scsi host instance
+ * @can_sleep: 1 or 0 when sleeping is permitted or not, respectively.
  *
  * Returns 0 on success, negative error code on failure.
  */
 
-static int do_abort(struct Scsi_Host *instance)
+static int do_abort(struct Scsi_Host *instance, unsigned int can_sleep)
 {
        struct NCR5380_hostdata *hostdata = shost_priv(instance);
        unsigned char *msgptr, phase, tmp;

Does that sound like a reasonable compromise?

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH] scsi/NCR5380: Remove in_interrupt() test
  2020-12-03 23:08   ` Finn Thain
@ 2020-12-04  8:38     ` Geert Uytterhoeven
  2020-12-04 16:08     ` Ahmed S. Darwish
  1 sibling, 0 replies; 12+ messages in thread
From: Geert Uytterhoeven @ 2020-12-04  8:38 UTC (permalink / raw)
  To: Finn Thain
  Cc: Sebastian Andrzej Siewior, Michael Schmitz, James E.J. Bottomley,
	Martin K. Petersen, Ahmed S. Darwish, Thomas Gleixner, scsi,
	Linux Kernel Mailing List

Hi Finn,

On Fri, Dec 4, 2020 at 12:11 AM Finn Thain <fthain@telegraphics.com.au> wrote:
> > --- a/drivers/scsi/g_NCR5380.c
> > +++ b/drivers/scsi/g_NCR5380.c
> > @@ -529,14 +529,14 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
> >               if (start == len - 128) {
> >                       /* Ignore End of DMA interrupt for the final buffer */
> >                       if (NCR5380_poll_politely(hostdata, hostdata->c400_ctl_status,
> > -                                               CSR_HOST_BUF_NOT_RDY, 0, HZ / 64) < 0)
> > +                                               CSR_HOST_BUF_NOT_RDY, 0, 0) < 0)
>
> You've put your finger on a known problem with certain
> NCR5380_poll_politely() call sites. That is, the nominal timeout, HZ / 64,
> is meaningless because it is ignored in atomic context. So you may as well
> specify 0 jiffies at these call sites. (There will be a 1 jiffy timeout
> applied regardless.)

Notwithstanding HZ / 64 breaks if HZ < 64.

Possible values of HZ in the kernel:

24
32
48
64
100
128
200
250
256
300
500
1000
1024
1200

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v2] scsi: NCR5380: Remove context check
  2020-12-01  6:46 [PATCH] scsi/NCR5380: Remove in_interrupt() test Finn Thain
  2020-12-01 17:05 ` Sebastian Andrzej Siewior
  2020-12-01 18:01 ` Michael Schmitz
@ 2020-12-04 15:32 ` Ahmed S. Darwish
  2020-12-05  4:28   ` Finn Thain
  2 siblings, 1 reply; 12+ messages in thread
From: Ahmed S. Darwish @ 2020-12-04 15:32 UTC (permalink / raw)
  To: Finn Thain
  Cc: Michael Schmitz, Geert Uytterhoeven, James E.J. Bottomley,
	Martin K. Petersen, Sebastian A. Siewior, Thomas Gleixner,
	linux-scsi, linux-kernel, Ahmed S. Darwish

NCR5380_poll_politely2() uses in_interrupt() and irqs_disabled() to
check if it is safe to sleep.

Such usage in drivers is phased out and Linus clearly requested that
code which changes behaviour depending on context should either be
separated, or the context be explicitly conveyed in an argument passed
by the caller.

Below is a context analysis of NCR5380_poll_politely2() uppermost
callers:

  - NCR5380_maybe_reset_bus(), task, invoked during device probe.
    -> NCR5380_poll_politely()
    -> do_abort()

  - NCR5380_select(), task, but can only sleep in the "release, then
    re-acquire" regions of the spinlock held by its caller.
    Sleeping invocations (lock released):
    -> NCR5380_poll_politely2()

    Atomic invocations (lock acquired):
    -> NCR5380_reselect()
       -> NCR5380_poll_politely()
       -> do_abort()
       -> NCR5380_transfer_pio()

  - NCR5380_intr(), interrupt handler
    -> NCR5380_dma_complete()
       -> NCR5380_transfer_pio()
	  -> NCR5380_poll_politely()
    -> NCR5380_reselect() (see above)

  - NCR5380_information_transfer(), task, but can only sleep in the
    "release, then re-acquire" regions of the caller-held spinlock.
    Sleeping invocations (lock released):
      - NCR5380_transfer_pio() -> NCR5380_poll_politely()
      - NCR5380_poll_politely()

    Atomic invocations (lock acquired):
      - NCR5380_transfer_dma()
	-> NCR5380_dma_recv_setup()
           => generic_NCR5380_precv() -> NCR5380_poll_politely()
	   => macscsi_pread() -> NCR5380_poll_politely()

	-> NCR5380_dma_send_setup()
 	   => generic_NCR5380_psend -> NCR5380_poll_politely2()
	   => macscsi_pwrite() -> NCR5380_poll_politely()

	-> NCR5380_poll_politely2()
        -> NCR5380_dma_complete()
           -> NCR5380_transfer_pio()
	      -> NCR5380_poll_politely()
      - NCR5380_transfer_pio() -> NCR5380_poll_politely

  - NCR5380_reselect(), atomic, always called with hostdata spinlock
    held.

Since NCR5380_poll_politely2() already takes a "wait" argument in
jiffies, use it to determine if the function can sleep. Modify atomic
callers, which passed an unused wait value in terms of HZ, to pass zero.

Suggested-by: Finn Thain <fthain@telegraphics.com.au>
Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: <linux-m68k@lists.linux-m68k.org>
---
 drivers/scsi/NCR5380.c   | 77 ++++++++++++++++++++++------------------
 drivers/scsi/NCR5380.h   |  3 +-
 drivers/scsi/g_NCR5380.c | 12 +++----
 drivers/scsi/mac_scsi.c  | 10 +++---
 4 files changed, 55 insertions(+), 47 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index d654a6cc4162..60200f61592e 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -132,7 +132,7 @@
 static unsigned int disconnect_mask = ~0;
 module_param(disconnect_mask, int, 0444);
 
-static int do_abort(struct Scsi_Host *);
+static int do_abort(struct Scsi_Host *, unsigned int);
 static void do_reset(struct Scsi_Host *);
 static void bus_reset_cleanup(struct Scsi_Host *);
 
@@ -197,7 +197,7 @@ static inline void set_resid_from_SCp(struct scsi_cmnd *cmd)
  * @reg2: Second 5380 register to poll
  * @bit2: Second bitmask to check
  * @val2: Second expected value
- * @wait: Time-out in jiffies
+ * @wait: Time-out in jiffies, 0 if sleeping is not allowed
  *
  * Polls the chip in a reasonably efficient manner waiting for an
  * event to occur. After a short quick poll we begin to yield the CPU
@@ -213,7 +213,7 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
                                   unsigned long wait)
 {
 	unsigned long n = hostdata->poll_loops;
-	unsigned long deadline = jiffies + wait;
+	unsigned long deadline;
 
 	do {
 		if ((NCR5380_read(reg1) & bit1) == val1)
@@ -223,10 +223,11 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
 		cpu_relax();
 	} while (n--);
 
-	if (irqs_disabled() || in_interrupt())
+	if (!wait)
 		return -ETIMEDOUT;
 
 	/* Repeatedly sleep for 1 ms until deadline */
+	deadline = jiffies + wait;
 	while (time_is_after_jiffies(deadline)) {
 		schedule_timeout_uninterruptible(1);
 		if ((NCR5380_read(reg1) & bit1) == val1)
@@ -486,7 +487,7 @@ static int NCR5380_maybe_reset_bus(struct Scsi_Host *instance)
 			break;
 		case 2:
 			shost_printk(KERN_ERR, instance, "bus busy, attempting abort\n");
-			do_abort(instance);
+			do_abort(instance, 1);
 			break;
 		case 4:
 			shost_printk(KERN_ERR, instance, "bus busy, attempting reset\n");
@@ -818,7 +819,7 @@ static void NCR5380_dma_complete(struct Scsi_Host *instance)
 			if (toPIO > 0) {
 				dsprintk(NDEBUG_DMA, instance,
 				         "Doing %d byte PIO to 0x%p\n", cnt, *data);
-				NCR5380_transfer_pio(instance, &p, &cnt, data);
+				NCR5380_transfer_pio(instance, &p, &cnt, data, 0);
 				*count -= toPIO - cnt;
 			}
 		}
@@ -1185,7 +1186,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 		goto out;
 	}
 	if (!hostdata->selecting) {
-		do_abort(instance);
+		do_abort(instance, 0);
 		return false;
 	}
 
@@ -1196,7 +1197,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 	len = 1;
 	data = tmp;
 	phase = PHASE_MSGOUT;
-	NCR5380_transfer_pio(instance, &phase, &len, &data);
+	NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 	if (len) {
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		cmd->result = DID_ERROR << 16;
@@ -1234,7 +1235,8 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
  *
  * Inputs : instance - instance of driver, *phase - pointer to
  * what phase is expected, *count - pointer to number of
- * bytes to transfer, **data - pointer to data pointer.
+ * bytes to transfer, **data - pointer to data pointer,
+ * can_sleep - 1 or 0 when sleeping is permitted or not, respectively.
  *
  * Returns : -1 when different phase is entered without transferring
  * maximum number of bytes, 0 if all bytes are transferred or exit
@@ -1253,7 +1255,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 
 static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 				unsigned char *phase, int *count,
-				unsigned char **data)
+				unsigned char **data, unsigned int can_sleep)
 {
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 	unsigned char p = *phase, tmp;
@@ -1274,7 +1276,8 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 		 * valid
 		 */
 
-		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, HZ) < 0)
+		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+					  HZ * can_sleep) < 0)
 			break;
 
 		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ asserted\n");
@@ -1320,7 +1323,7 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 		}
 
 		if (NCR5380_poll_politely(hostdata,
-		                          STATUS_REG, SR_REQ, 0, 5 * HZ) < 0)
+		                          STATUS_REG, SR_REQ, 0, 5 * HZ * can_sleep) < 0)
 			break;
 
 		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ negated, handshake complete\n");
@@ -1395,11 +1398,12 @@ static void do_reset(struct Scsi_Host *instance)
  * do_abort - abort the currently established nexus by going to
  * MESSAGE OUT phase and sending an ABORT message.
  * @instance: relevant scsi host instance
+ * @can_sleep: 1 or 0 when sleeping is permitted or not, respectively
  *
  * Returns 0 on success, negative error code on failure.
  */
 
-static int do_abort(struct Scsi_Host *instance)
+static int do_abort(struct Scsi_Host *instance, unsigned int can_sleep)
 {
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 	unsigned char *msgptr, phase, tmp;
@@ -1419,7 +1423,8 @@ static int do_abort(struct Scsi_Host *instance)
 	 * the target sees, so we just handshake.
 	 */
 
-	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, 10 * HZ);
+	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+				   10 * HZ * can_sleep);
 	if (rc < 0)
 		goto out;
 
@@ -1430,7 +1435,8 @@ static int do_abort(struct Scsi_Host *instance)
 	if (tmp != PHASE_MSGOUT) {
 		NCR5380_write(INITIATOR_COMMAND_REG,
 		              ICR_BASE | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
-		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0, 3 * HZ);
+		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0,
+					   3 * HZ * can_sleep);
 		if (rc < 0)
 			goto out;
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
@@ -1440,7 +1446,7 @@ static int do_abort(struct Scsi_Host *instance)
 	msgptr = &tmp;
 	len = 1;
 	phase = PHASE_MSGOUT;
-	NCR5380_transfer_pio(instance, &phase, &len, &msgptr);
+	NCR5380_transfer_pio(instance, &phase, &len, &msgptr, can_sleep);
 	if (len)
 		rc = -ENXIO;
 
@@ -1619,12 +1625,12 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 			 */
 
 			if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
-			                          BASR_DRQ, BASR_DRQ, HZ) < 0) {
+			                          BASR_DRQ, BASR_DRQ, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA read: DRQ timeout\n");
 			}
 			if (NCR5380_poll_politely(hostdata, STATUS_REG,
-			                          SR_REQ, 0, HZ) < 0) {
+			                          SR_REQ, 0, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA read: !REQ timeout\n");
 			}
@@ -1636,7 +1642,7 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 			 */
 			if (NCR5380_poll_politely2(hostdata,
 			     BUS_AND_STATUS_REG, BASR_DRQ, BASR_DRQ,
-			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, HZ) < 0) {
+			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA write: DRQ and phase timeout\n");
 			}
@@ -1733,7 +1739,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 #if (NDEBUG & NDEBUG_NO_DATAOUT)
 				shost_printk(KERN_DEBUG, instance, "NDEBUG_NO_DATAOUT set, attempted DATAOUT aborted\n");
 				sink = 1;
-				do_abort(instance);
+				do_abort(instance, 0);
 				cmd->result = DID_ERROR << 16;
 				complete_cmd(instance, cmd);
 				hostdata->connected = NULL;
@@ -1789,7 +1795,8 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 							   NCR5380_PIO_CHUNK_SIZE);
 					len = transfersize;
 					NCR5380_transfer_pio(instance, &phase, &len,
-					                     (unsigned char **)&cmd->SCp.ptr);
+					                     (unsigned char **)&cmd->SCp.ptr,
+							     0);
 					cmd->SCp.this_residual -= transfersize - len;
 				}
 #ifdef CONFIG_SUN3
@@ -1800,7 +1807,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 			case PHASE_MSGIN:
 				len = 1;
 				data = &tmp;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				cmd->SCp.Message = tmp;
 
 				switch (tmp) {
@@ -1907,7 +1914,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 					len = 2;
 					data = extended_msg + 1;
 					phase = PHASE_MSGIN;
-					NCR5380_transfer_pio(instance, &phase, &len, &data);
+					NCR5380_transfer_pio(instance, &phase, &len, &data, 1);
 					dsprintk(NDEBUG_EXTENDED, instance, "length %d, code 0x%02x\n",
 					         (int)extended_msg[1],
 					         (int)extended_msg[2]);
@@ -1920,7 +1927,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 						data = extended_msg + 3;
 						phase = PHASE_MSGIN;
 
-						NCR5380_transfer_pio(instance, &phase, &len, &data);
+						NCR5380_transfer_pio(instance, &phase, &len, &data, 1);
 						dsprintk(NDEBUG_EXTENDED, instance, "message received, residual %d\n",
 						         len);
 
@@ -1967,7 +1974,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				len = 1;
 				data = &msgout;
 				hostdata->last_message = msgout;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				if (msgout == ABORT) {
 					hostdata->connected = NULL;
 					hostdata->busy[scmd_id(cmd)] &= ~(1 << cmd->device->lun);
@@ -1986,12 +1993,12 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				 * PSEUDO-DMA architecture we should probably
 				 * use the dma transfer function.
 				 */
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				break;
 			case PHASE_STATIN:
 				len = 1;
 				data = &tmp;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				cmd->SCp.Status = tmp;
 				break;
 			default:
@@ -2050,7 +2057,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 
 	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_BSY);
 	if (NCR5380_poll_politely(hostdata,
-	                          STATUS_REG, SR_SEL, 0, 2 * HZ) < 0) {
+	                          STATUS_REG, SR_SEL, 0, 0) < 0) {
 		shost_printk(KERN_ERR, instance, "reselect: !SEL timeout\n");
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		return;
@@ -2062,12 +2069,12 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 	 */
 
 	if (NCR5380_poll_politely(hostdata,
-	                          STATUS_REG, SR_REQ, SR_REQ, 2 * HZ) < 0) {
+	                          STATUS_REG, SR_REQ, SR_REQ, 0) < 0) {
 		if ((NCR5380_read(STATUS_REG) & (SR_BSY | SR_SEL)) == 0)
 			/* BUS FREE phase */
 			return;
 		shost_printk(KERN_ERR, instance, "reselect: REQ timeout\n");
-		do_abort(instance);
+		do_abort(instance, 0);
 		return;
 	}
 
@@ -2083,10 +2090,10 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		unsigned char *data = msg;
 		unsigned char phase = PHASE_MSGIN;
 
-		NCR5380_transfer_pio(instance, &phase, &len, &data);
+		NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 
 		if (len) {
-			do_abort(instance);
+			do_abort(instance, 0);
 			return;
 		}
 	}
@@ -2096,7 +2103,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		shost_printk(KERN_ERR, instance, "expecting IDENTIFY message, got ");
 		spi_print_msg(msg);
 		printk("\n");
-		do_abort(instance);
+		do_abort(instance, 0);
 		return;
 	}
 	lun = msg[0] & 0x07;
@@ -2136,7 +2143,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		 * Since we have an established nexus that we can't do anything
 		 * with, we must abort it.
 		 */
-		if (do_abort(instance) == 0)
+		if (do_abort(instance, 0) == 0)
 			hostdata->busy[target] &= ~(1 << lun);
 		return;
 	}
@@ -2283,7 +2290,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
 		dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
 		hostdata->connected = NULL;
 		hostdata->dma_len = 0;
-		if (do_abort(instance) < 0) {
+		if (do_abort(instance, 0) < 0) {
 			set_host_byte(cmd, DID_ERROR);
 			complete_cmd(instance, cmd);
 			result = FAILED;
diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
index 5935fd6d1a05..8a3b41932288 100644
--- a/drivers/scsi/NCR5380.h
+++ b/drivers/scsi/NCR5380.h
@@ -277,7 +277,8 @@ static const char *NCR5380_info(struct Scsi_Host *instance);
 static void NCR5380_reselect(struct Scsi_Host *instance);
 static bool NCR5380_select(struct Scsi_Host *, struct scsi_cmnd *);
 static int NCR5380_transfer_dma(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
-static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
+static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data,
+				unsigned int can_sleep);
 static int NCR5380_poll_politely2(struct NCR5380_hostdata *,
                                   unsigned int, u8, u8,
                                   unsigned int, u8, u8, unsigned long);
diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 29e4cdcade72..2df2f38a9b12 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -529,14 +529,14 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
 		if (start == len - 128) {
 			/* Ignore End of DMA interrupt for the final buffer */
 			if (NCR5380_poll_politely(hostdata, hostdata->c400_ctl_status,
-			                          CSR_HOST_BUF_NOT_RDY, 0, HZ / 64) < 0)
+			                          CSR_HOST_BUF_NOT_RDY, 0, 0) < 0)
 				break;
 		} else {
 			if (NCR5380_poll_politely2(hostdata, hostdata->c400_ctl_status,
 			                           CSR_HOST_BUF_NOT_RDY, 0,
 			                           hostdata->c400_ctl_status,
 			                           CSR_GATED_53C80_IRQ,
-			                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
+			                           CSR_GATED_53C80_IRQ, 0) < 0 ||
 			    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY)
 				break;
 		}
@@ -565,7 +565,7 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
 	if (residual == 0 && NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                                           BASR_END_DMA_TRANSFER,
 	                                           BASR_END_DMA_TRANSFER,
-	                                           HZ / 64) < 0)
+						   0) < 0)
 		scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
 		            __func__);
 
@@ -597,7 +597,7 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
 		                           CSR_HOST_BUF_NOT_RDY, 0,
 		                           hostdata->c400_ctl_status,
 		                           CSR_GATED_53C80_IRQ,
-		                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
+		                           CSR_GATED_53C80_IRQ, 0) < 0 ||
 		    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) {
 			/* Both 128 B buffers are in use */
 			if (start >= 128)
@@ -644,13 +644,13 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
 	if (residual == 0) {
 		if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 		                          TCR_LAST_BYTE_SENT, TCR_LAST_BYTE_SENT,
-		                          HZ / 64) < 0)
+					  0) < 0)
 			scmd_printk(KERN_ERR, hostdata->connected,
 			            "%s: Last Byte Sent timeout\n", __func__);
 
 		if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 		                          BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER,
-		                          HZ / 64) < 0)
+					  0) < 0)
 			scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
 			            __func__);
 	}
diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index b5dde9d0d054..5c808fbc6ce2 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -285,7 +285,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
-	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
+	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
 		int bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
@@ -304,7 +304,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, HZ / 64) < 0)
+		                           BASR_ACK, 0) < 0)
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
@@ -344,7 +344,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
-	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
+	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
 		int bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
@@ -362,7 +362,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 			                          TCR_LAST_BYTE_SENT,
 			                          TCR_LAST_BYTE_SENT,
-			                          HZ / 64) < 0) {
+			                          0) < 0) {
 				scmd_printk(KERN_ERR, hostdata->connected,
 				            "%s: Last Byte Sent timeout\n", __func__);
 				result = -1;
@@ -372,7 +372,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, HZ / 64) < 0)
+		                           BASR_ACK, 0) < 0)
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
-- 
2.29.2


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH] scsi/NCR5380: Remove in_interrupt() test
  2020-12-03 23:08   ` Finn Thain
  2020-12-04  8:38     ` Geert Uytterhoeven
@ 2020-12-04 16:08     ` Ahmed S. Darwish
  1 sibling, 0 replies; 12+ messages in thread
From: Ahmed S. Darwish @ 2020-12-04 16:08 UTC (permalink / raw)
  To: Finn Thain
  Cc: Sebastian Andrzej Siewior, Michael Schmitz, James E.J. Bottomley,
	Martin K. Petersen, Thomas Gleixner, linux-scsi, linux-kernel

On Fri, Dec 04, 2020 at 10:08:08AM +1100, Finn Thain wrote:
...
>
> You've put your finger on a known problem with certain
> NCR5380_poll_politely() call sites. That is, the nominal timeout, HZ / 64,
> is meaningless because it is ignored in atomic context. So you may as well
> specify 0 jiffies at these call sites. (There will be a 1 jiffy timeout
> applied regardless.)
...
>
> However, I can see the value in your approach, i.e. passing a zero timeout
> to NCR5380_poll_politely() whenever that argument is unused. And I agree
> that this could then be used to inhibit sleeping, rather than testing
> irqs_disabled().
>
> So if you really don't like irqs_disabled(), perhaps you can just keep the
> better parts of your two attempts, i.e. passing 0 to
> NCR5380_poll_politely() where appropriate and facilitating that by adding
> a new can_sleep parameter to do_abort() and NCR5380_transfer_pio(), as in,
...
>
> Does that sound like a reasonable compromise?
>

Yes, of course. Thanks a lot.

I've sent a v2.

--
Ahmed S. Darwish
Linutronix GmbH

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v2] scsi: NCR5380: Remove context check
  2020-12-04 15:32 ` [PATCH v2] scsi: NCR5380: Remove context check Ahmed S. Darwish
@ 2020-12-05  4:28   ` Finn Thain
  2020-12-06  7:51     ` [PATCH v3] " Ahmed S. Darwish
  0 siblings, 1 reply; 12+ messages in thread
From: Finn Thain @ 2020-12-05  4:28 UTC (permalink / raw)
  To: Ahmed S. Darwish
  Cc: Michael Schmitz, Geert Uytterhoeven, James E.J. Bottomley,
	Martin K. Petersen, Sebastian A. Siewior, Thomas Gleixner,
	linux-scsi, linux-kernel


On Fri, 4 Dec 2020, Ahmed S. Darwish wrote:

> NCR5380_poll_politely2() uses in_interrupt() and irqs_disabled() to
> check if it is safe to sleep.
> 
> Such usage in drivers is phased out and Linus clearly requested that
> code which changes behaviour depending on context should either be
> separated, or the context be explicitly conveyed in an argument passed
> by the caller.
> 
> Below is a context analysis of NCR5380_poll_politely2() uppermost
> callers:
> 
>   - NCR5380_maybe_reset_bus(), task, invoked during device probe.
>     -> NCR5380_poll_politely()
>     -> do_abort()
> 
>   - NCR5380_select(), task, but can only sleep in the "release, then
>     re-acquire" regions of the spinlock held by its caller.
>     Sleeping invocations (lock released):
>     -> NCR5380_poll_politely2()
> 
>     Atomic invocations (lock acquired):
>     -> NCR5380_reselect()
>        -> NCR5380_poll_politely()
>        -> do_abort()
>        -> NCR5380_transfer_pio()
> 
>   - NCR5380_intr(), interrupt handler
>     -> NCR5380_dma_complete()
>        -> NCR5380_transfer_pio()
> 	  -> NCR5380_poll_politely()
>     -> NCR5380_reselect() (see above)
> 
>   - NCR5380_information_transfer(), task, but can only sleep in the
>     "release, then re-acquire" regions of the caller-held spinlock.
>     Sleeping invocations (lock released):
>       - NCR5380_transfer_pio() -> NCR5380_poll_politely()
>       - NCR5380_poll_politely()
> 
>     Atomic invocations (lock acquired):
>       - NCR5380_transfer_dma()
> 	-> NCR5380_dma_recv_setup()
>            => generic_NCR5380_precv() -> NCR5380_poll_politely()
> 	   => macscsi_pread() -> NCR5380_poll_politely()
> 
> 	-> NCR5380_dma_send_setup()
>  	   => generic_NCR5380_psend -> NCR5380_poll_politely2()
> 	   => macscsi_pwrite() -> NCR5380_poll_politely()
> 
> 	-> NCR5380_poll_politely2()
>         -> NCR5380_dma_complete()
>            -> NCR5380_transfer_pio()
> 	      -> NCR5380_poll_politely()
>       - NCR5380_transfer_pio() -> NCR5380_poll_politely
> 
>   - NCR5380_reselect(), atomic, always called with hostdata spinlock
>     held.
> 
> Since NCR5380_poll_politely2() already takes a "wait" argument in
> jiffies, use it to determine if the function can sleep. Modify atomic
> callers, which passed an unused wait value in terms of HZ, to pass zero.
> 
> Suggested-by: Finn Thain <fthain@telegraphics.com.au>
> Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Cc: Michael Schmitz <schmitzmic@gmail.com>
> Cc: <linux-m68k@lists.linux-m68k.org>
> ---
>  drivers/scsi/NCR5380.c   | 77 ++++++++++++++++++++++------------------
>  drivers/scsi/NCR5380.h   |  3 +-
>  drivers/scsi/g_NCR5380.c | 12 +++----
>  drivers/scsi/mac_scsi.c  | 10 +++---
>  4 files changed, 55 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index d654a6cc4162..60200f61592e 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -132,7 +132,7 @@
>  static unsigned int disconnect_mask = ~0;
>  module_param(disconnect_mask, int, 0444);
>  
> -static int do_abort(struct Scsi_Host *);
> +static int do_abort(struct Scsi_Host *, unsigned int);
>  static void do_reset(struct Scsi_Host *);
>  static void bus_reset_cleanup(struct Scsi_Host *);
>  
> @@ -197,7 +197,7 @@ static inline void set_resid_from_SCp(struct scsi_cmnd *cmd)
>   * @reg2: Second 5380 register to poll
>   * @bit2: Second bitmask to check
>   * @val2: Second expected value
> - * @wait: Time-out in jiffies
> + * @wait: Time-out in jiffies, 0 if sleeping is not allowed
>   *
>   * Polls the chip in a reasonably efficient manner waiting for an
>   * event to occur. After a short quick poll we begin to yield the CPU
> @@ -213,7 +213,7 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
>                                    unsigned long wait)
>  {
>  	unsigned long n = hostdata->poll_loops;
> -	unsigned long deadline = jiffies + wait;
> +	unsigned long deadline;
>  
>  	do {
>  		if ((NCR5380_read(reg1) & bit1) == val1)
> @@ -223,10 +223,11 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
>  		cpu_relax();
>  	} while (n--);
>  
> -	if (irqs_disabled() || in_interrupt())
> +	if (!wait)
>  		return -ETIMEDOUT;
>  
>  	/* Repeatedly sleep for 1 ms until deadline */
> +	deadline = jiffies + wait;
>  	while (time_is_after_jiffies(deadline)) {
>  		schedule_timeout_uninterruptible(1);
>  		if ((NCR5380_read(reg1) & bit1) == val1)

The deadline assignment shouldn't be moved. That's a behavioural change 
and doesn't fit under the stated aim of this patch. Also, it isn't 
actually a desirable change: the argument to this function is the overall 
wait time, not just the sleep limit.

The rest looks ok.

^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v3] scsi: NCR5380: Remove context check
  2020-12-05  4:28   ` Finn Thain
@ 2020-12-06  7:51     ` Ahmed S. Darwish
  2020-12-08  0:12       ` Finn Thain
                         ` (2 more replies)
  0 siblings, 3 replies; 12+ messages in thread
From: Ahmed S. Darwish @ 2020-12-06  7:51 UTC (permalink / raw)
  To: Finn Thain
  Cc: Michael Schmitz, Geert Uytterhoeven, James E.J. Bottomley,
	Martin K. Petersen, Sebastian A. Siewior, Thomas Gleixner,
	linux-scsi, linux-kernel, Ahmed S. Darwish

NCR5380_poll_politely2() uses in_interrupt() and irqs_disabled() to
check if it is safe to sleep.

Such usage in drivers is phased out and Linus clearly requested that
code which changes behaviour depending on context should either be
separated, or the context be explicitly conveyed in an argument passed
by the caller.

Below is a context analysis of NCR5380_poll_politely2() uppermost
callers:

  - NCR5380_maybe_reset_bus(), task, invoked during device probe.
    -> NCR5380_poll_politely()
    -> do_abort()

  - NCR5380_select(), task, but can only sleep in the "release, then
    re-acquire" regions of the spinlock held by its caller.
    Sleeping invocations (lock released):
    -> NCR5380_poll_politely2()

    Atomic invocations (lock acquired):
    -> NCR5380_reselect()
       -> NCR5380_poll_politely()
       -> do_abort()
       -> NCR5380_transfer_pio()

  - NCR5380_intr(), interrupt handler
    -> NCR5380_dma_complete()
       -> NCR5380_transfer_pio()
	  -> NCR5380_poll_politely()
    -> NCR5380_reselect() (see above)

  - NCR5380_information_transfer(), task, but can only sleep in the
    "release, then re-acquire" regions of the caller-held spinlock.
    Sleeping invocations (lock released):
      - NCR5380_transfer_pio() -> NCR5380_poll_politely()
      - NCR5380_poll_politely()

    Atomic invocations (lock acquired):
      - NCR5380_transfer_dma()
	-> NCR5380_dma_recv_setup()
           => generic_NCR5380_precv() -> NCR5380_poll_politely()
	   => macscsi_pread() -> NCR5380_poll_politely()

	-> NCR5380_dma_send_setup()
 	   => generic_NCR5380_psend -> NCR5380_poll_politely2()
	   => macscsi_pwrite() -> NCR5380_poll_politely()

	-> NCR5380_poll_politely2()
        -> NCR5380_dma_complete()
           -> NCR5380_transfer_pio()
	      -> NCR5380_poll_politely()
      - NCR5380_transfer_pio() -> NCR5380_poll_politely

  - NCR5380_reselect(), atomic, always called with hostdata spinlock
    held.

Since NCR5380_poll_politely2() already takes a "wait" argument in
jiffies, use it to determine if the function can sleep. Modify atomic
callers, which passed an unused wait value in terms of HZ, to pass zero.

Suggested-by: Finn Thain <fthain@telegraphics.com.au>
Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: <linux-m68k@lists.linux-m68k.org>
---
 drivers/scsi/NCR5380.c   | 74 ++++++++++++++++++++++------------------
 drivers/scsi/NCR5380.h   |  3 +-
 drivers/scsi/g_NCR5380.c | 12 +++----
 drivers/scsi/mac_scsi.c  | 10 +++---
 4 files changed, 53 insertions(+), 46 deletions(-)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index d654a6cc4162..448cd22214c0 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -132,7 +132,7 @@
 static unsigned int disconnect_mask = ~0;
 module_param(disconnect_mask, int, 0444);
 
-static int do_abort(struct Scsi_Host *);
+static int do_abort(struct Scsi_Host *, unsigned int);
 static void do_reset(struct Scsi_Host *);
 static void bus_reset_cleanup(struct Scsi_Host *);
 
@@ -197,7 +197,7 @@ static inline void set_resid_from_SCp(struct scsi_cmnd *cmd)
  * @reg2: Second 5380 register to poll
  * @bit2: Second bitmask to check
  * @val2: Second expected value
- * @wait: Time-out in jiffies
+ * @wait: Time-out in jiffies, 0 if sleeping is not allowed
  *
  * Polls the chip in a reasonably efficient manner waiting for an
  * event to occur. After a short quick poll we begin to yield the CPU
@@ -223,7 +223,7 @@ static int NCR5380_poll_politely2(struct NCR5380_hostdata *hostdata,
 		cpu_relax();
 	} while (n--);
 
-	if (irqs_disabled() || in_interrupt())
+	if (!wait)
 		return -ETIMEDOUT;
 
 	/* Repeatedly sleep for 1 ms until deadline */
@@ -486,7 +486,7 @@ static int NCR5380_maybe_reset_bus(struct Scsi_Host *instance)
 			break;
 		case 2:
 			shost_printk(KERN_ERR, instance, "bus busy, attempting abort\n");
-			do_abort(instance);
+			do_abort(instance, 1);
 			break;
 		case 4:
 			shost_printk(KERN_ERR, instance, "bus busy, attempting reset\n");
@@ -818,7 +818,7 @@ static void NCR5380_dma_complete(struct Scsi_Host *instance)
 			if (toPIO > 0) {
 				dsprintk(NDEBUG_DMA, instance,
 				         "Doing %d byte PIO to 0x%p\n", cnt, *data);
-				NCR5380_transfer_pio(instance, &p, &cnt, data);
+				NCR5380_transfer_pio(instance, &p, &cnt, data, 0);
 				*count -= toPIO - cnt;
 			}
 		}
@@ -1185,7 +1185,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 		goto out;
 	}
 	if (!hostdata->selecting) {
-		do_abort(instance);
+		do_abort(instance, 0);
 		return false;
 	}
 
@@ -1196,7 +1196,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 	len = 1;
 	data = tmp;
 	phase = PHASE_MSGOUT;
-	NCR5380_transfer_pio(instance, &phase, &len, &data);
+	NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 	if (len) {
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		cmd->result = DID_ERROR << 16;
@@ -1234,7 +1234,8 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
  *
  * Inputs : instance - instance of driver, *phase - pointer to
  * what phase is expected, *count - pointer to number of
- * bytes to transfer, **data - pointer to data pointer.
+ * bytes to transfer, **data - pointer to data pointer,
+ * can_sleep - 1 or 0 when sleeping is permitted or not, respectively.
  *
  * Returns : -1 when different phase is entered without transferring
  * maximum number of bytes, 0 if all bytes are transferred or exit
@@ -1253,7 +1254,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 
 static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 				unsigned char *phase, int *count,
-				unsigned char **data)
+				unsigned char **data, unsigned int can_sleep)
 {
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 	unsigned char p = *phase, tmp;
@@ -1274,7 +1275,8 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 		 * valid
 		 */
 
-		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, HZ) < 0)
+		if (NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+					  HZ * can_sleep) < 0)
 			break;
 
 		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ asserted\n");
@@ -1320,7 +1322,7 @@ static int NCR5380_transfer_pio(struct Scsi_Host *instance,
 		}
 
 		if (NCR5380_poll_politely(hostdata,
-		                          STATUS_REG, SR_REQ, 0, 5 * HZ) < 0)
+		                          STATUS_REG, SR_REQ, 0, 5 * HZ * can_sleep) < 0)
 			break;
 
 		dsprintk(NDEBUG_HANDSHAKE, instance, "REQ negated, handshake complete\n");
@@ -1395,11 +1397,12 @@ static void do_reset(struct Scsi_Host *instance)
  * do_abort - abort the currently established nexus by going to
  * MESSAGE OUT phase and sending an ABORT message.
  * @instance: relevant scsi host instance
+ * @can_sleep: 1 or 0 when sleeping is permitted or not, respectively
  *
  * Returns 0 on success, negative error code on failure.
  */
 
-static int do_abort(struct Scsi_Host *instance)
+static int do_abort(struct Scsi_Host *instance, unsigned int can_sleep)
 {
 	struct NCR5380_hostdata *hostdata = shost_priv(instance);
 	unsigned char *msgptr, phase, tmp;
@@ -1419,7 +1422,8 @@ static int do_abort(struct Scsi_Host *instance)
 	 * the target sees, so we just handshake.
 	 */
 
-	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ, 10 * HZ);
+	rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, SR_REQ,
+				   10 * HZ * can_sleep);
 	if (rc < 0)
 		goto out;
 
@@ -1430,7 +1434,8 @@ static int do_abort(struct Scsi_Host *instance)
 	if (tmp != PHASE_MSGOUT) {
 		NCR5380_write(INITIATOR_COMMAND_REG,
 		              ICR_BASE | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
-		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0, 3 * HZ);
+		rc = NCR5380_poll_politely(hostdata, STATUS_REG, SR_REQ, 0,
+					   3 * HZ * can_sleep);
 		if (rc < 0)
 			goto out;
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
@@ -1440,7 +1445,7 @@ static int do_abort(struct Scsi_Host *instance)
 	msgptr = &tmp;
 	len = 1;
 	phase = PHASE_MSGOUT;
-	NCR5380_transfer_pio(instance, &phase, &len, &msgptr);
+	NCR5380_transfer_pio(instance, &phase, &len, &msgptr, can_sleep);
 	if (len)
 		rc = -ENXIO;
 
@@ -1619,12 +1624,12 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 			 */
 
 			if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
-			                          BASR_DRQ, BASR_DRQ, HZ) < 0) {
+			                          BASR_DRQ, BASR_DRQ, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA read: DRQ timeout\n");
 			}
 			if (NCR5380_poll_politely(hostdata, STATUS_REG,
-			                          SR_REQ, 0, HZ) < 0) {
+			                          SR_REQ, 0, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA read: !REQ timeout\n");
 			}
@@ -1636,7 +1641,7 @@ static int NCR5380_transfer_dma(struct Scsi_Host *instance,
 			 */
 			if (NCR5380_poll_politely2(hostdata,
 			     BUS_AND_STATUS_REG, BASR_DRQ, BASR_DRQ,
-			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, HZ) < 0) {
+			     BUS_AND_STATUS_REG, BASR_PHASE_MATCH, 0, 0) < 0) {
 				result = -1;
 				shost_printk(KERN_ERR, instance, "PDMA write: DRQ and phase timeout\n");
 			}
@@ -1733,7 +1738,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 #if (NDEBUG & NDEBUG_NO_DATAOUT)
 				shost_printk(KERN_DEBUG, instance, "NDEBUG_NO_DATAOUT set, attempted DATAOUT aborted\n");
 				sink = 1;
-				do_abort(instance);
+				do_abort(instance, 0);
 				cmd->result = DID_ERROR << 16;
 				complete_cmd(instance, cmd);
 				hostdata->connected = NULL;
@@ -1789,7 +1794,8 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 							   NCR5380_PIO_CHUNK_SIZE);
 					len = transfersize;
 					NCR5380_transfer_pio(instance, &phase, &len,
-					                     (unsigned char **)&cmd->SCp.ptr);
+					                     (unsigned char **)&cmd->SCp.ptr,
+							     0);
 					cmd->SCp.this_residual -= transfersize - len;
 				}
 #ifdef CONFIG_SUN3
@@ -1800,7 +1806,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 			case PHASE_MSGIN:
 				len = 1;
 				data = &tmp;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				cmd->SCp.Message = tmp;
 
 				switch (tmp) {
@@ -1907,7 +1913,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 					len = 2;
 					data = extended_msg + 1;
 					phase = PHASE_MSGIN;
-					NCR5380_transfer_pio(instance, &phase, &len, &data);
+					NCR5380_transfer_pio(instance, &phase, &len, &data, 1);
 					dsprintk(NDEBUG_EXTENDED, instance, "length %d, code 0x%02x\n",
 					         (int)extended_msg[1],
 					         (int)extended_msg[2]);
@@ -1920,7 +1926,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 						data = extended_msg + 3;
 						phase = PHASE_MSGIN;
 
-						NCR5380_transfer_pio(instance, &phase, &len, &data);
+						NCR5380_transfer_pio(instance, &phase, &len, &data, 1);
 						dsprintk(NDEBUG_EXTENDED, instance, "message received, residual %d\n",
 						         len);
 
@@ -1967,7 +1973,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				len = 1;
 				data = &msgout;
 				hostdata->last_message = msgout;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				if (msgout == ABORT) {
 					hostdata->connected = NULL;
 					hostdata->busy[scmd_id(cmd)] &= ~(1 << cmd->device->lun);
@@ -1986,12 +1992,12 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				 * PSEUDO-DMA architecture we should probably
 				 * use the dma transfer function.
 				 */
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				break;
 			case PHASE_STATIN:
 				len = 1;
 				data = &tmp;
-				NCR5380_transfer_pio(instance, &phase, &len, &data);
+				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				cmd->SCp.Status = tmp;
 				break;
 			default:
@@ -2050,7 +2056,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 
 	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_BSY);
 	if (NCR5380_poll_politely(hostdata,
-	                          STATUS_REG, SR_SEL, 0, 2 * HZ) < 0) {
+	                          STATUS_REG, SR_SEL, 0, 0) < 0) {
 		shost_printk(KERN_ERR, instance, "reselect: !SEL timeout\n");
 		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
 		return;
@@ -2062,12 +2068,12 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 	 */
 
 	if (NCR5380_poll_politely(hostdata,
-	                          STATUS_REG, SR_REQ, SR_REQ, 2 * HZ) < 0) {
+	                          STATUS_REG, SR_REQ, SR_REQ, 0) < 0) {
 		if ((NCR5380_read(STATUS_REG) & (SR_BSY | SR_SEL)) == 0)
 			/* BUS FREE phase */
 			return;
 		shost_printk(KERN_ERR, instance, "reselect: REQ timeout\n");
-		do_abort(instance);
+		do_abort(instance, 0);
 		return;
 	}
 
@@ -2083,10 +2089,10 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		unsigned char *data = msg;
 		unsigned char phase = PHASE_MSGIN;
 
-		NCR5380_transfer_pio(instance, &phase, &len, &data);
+		NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 
 		if (len) {
-			do_abort(instance);
+			do_abort(instance, 0);
 			return;
 		}
 	}
@@ -2096,7 +2102,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		shost_printk(KERN_ERR, instance, "expecting IDENTIFY message, got ");
 		spi_print_msg(msg);
 		printk("\n");
-		do_abort(instance);
+		do_abort(instance, 0);
 		return;
 	}
 	lun = msg[0] & 0x07;
@@ -2136,7 +2142,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 		 * Since we have an established nexus that we can't do anything
 		 * with, we must abort it.
 		 */
-		if (do_abort(instance) == 0)
+		if (do_abort(instance, 0) == 0)
 			hostdata->busy[target] &= ~(1 << lun);
 		return;
 	}
@@ -2283,7 +2289,7 @@ static int NCR5380_abort(struct scsi_cmnd *cmd)
 		dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
 		hostdata->connected = NULL;
 		hostdata->dma_len = 0;
-		if (do_abort(instance) < 0) {
+		if (do_abort(instance, 0) < 0) {
 			set_host_byte(cmd, DID_ERROR);
 			complete_cmd(instance, cmd);
 			result = FAILED;
diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
index 5935fd6d1a05..8a3b41932288 100644
--- a/drivers/scsi/NCR5380.h
+++ b/drivers/scsi/NCR5380.h
@@ -277,7 +277,8 @@ static const char *NCR5380_info(struct Scsi_Host *instance);
 static void NCR5380_reselect(struct Scsi_Host *instance);
 static bool NCR5380_select(struct Scsi_Host *, struct scsi_cmnd *);
 static int NCR5380_transfer_dma(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
-static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data);
+static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data,
+				unsigned int can_sleep);
 static int NCR5380_poll_politely2(struct NCR5380_hostdata *,
                                   unsigned int, u8, u8,
                                   unsigned int, u8, u8, unsigned long);
diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 29e4cdcade72..2df2f38a9b12 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -529,14 +529,14 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
 		if (start == len - 128) {
 			/* Ignore End of DMA interrupt for the final buffer */
 			if (NCR5380_poll_politely(hostdata, hostdata->c400_ctl_status,
-			                          CSR_HOST_BUF_NOT_RDY, 0, HZ / 64) < 0)
+			                          CSR_HOST_BUF_NOT_RDY, 0, 0) < 0)
 				break;
 		} else {
 			if (NCR5380_poll_politely2(hostdata, hostdata->c400_ctl_status,
 			                           CSR_HOST_BUF_NOT_RDY, 0,
 			                           hostdata->c400_ctl_status,
 			                           CSR_GATED_53C80_IRQ,
-			                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
+			                           CSR_GATED_53C80_IRQ, 0) < 0 ||
 			    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY)
 				break;
 		}
@@ -565,7 +565,7 @@ static inline int generic_NCR5380_precv(struct NCR5380_hostdata *hostdata,
 	if (residual == 0 && NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                                           BASR_END_DMA_TRANSFER,
 	                                           BASR_END_DMA_TRANSFER,
-	                                           HZ / 64) < 0)
+						   0) < 0)
 		scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
 		            __func__);
 
@@ -597,7 +597,7 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
 		                           CSR_HOST_BUF_NOT_RDY, 0,
 		                           hostdata->c400_ctl_status,
 		                           CSR_GATED_53C80_IRQ,
-		                           CSR_GATED_53C80_IRQ, HZ / 64) < 0 ||
+		                           CSR_GATED_53C80_IRQ, 0) < 0 ||
 		    NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) {
 			/* Both 128 B buffers are in use */
 			if (start >= 128)
@@ -644,13 +644,13 @@ static inline int generic_NCR5380_psend(struct NCR5380_hostdata *hostdata,
 	if (residual == 0) {
 		if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 		                          TCR_LAST_BYTE_SENT, TCR_LAST_BYTE_SENT,
-		                          HZ / 64) < 0)
+					  0) < 0)
 			scmd_printk(KERN_ERR, hostdata->connected,
 			            "%s: Last Byte Sent timeout\n", __func__);
 
 		if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 		                          BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER,
-		                          HZ / 64) < 0)
+					  0) < 0)
 			scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout\n",
 			            __func__);
 	}
diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index b5dde9d0d054..5c808fbc6ce2 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -285,7 +285,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
-	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
+	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
 		int bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
@@ -304,7 +304,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, HZ / 64) < 0)
+		                           BASR_ACK, 0) < 0)
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
@@ -344,7 +344,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 
 	while (!NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG,
 	                              BASR_DRQ | BASR_PHASE_MATCH,
-	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
+	                              BASR_DRQ | BASR_PHASE_MATCH, 0)) {
 		int bytes;
 
 		if (macintosh_config->ident == MAC_MODEL_IIFX)
@@ -362,7 +362,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 			                          TCR_LAST_BYTE_SENT,
 			                          TCR_LAST_BYTE_SENT,
-			                          HZ / 64) < 0) {
+			                          0) < 0) {
 				scmd_printk(KERN_ERR, hostdata->connected,
 				            "%s: Last Byte Sent timeout\n", __func__);
 				result = -1;
@@ -372,7 +372,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
-		                           BASR_ACK, HZ / 64) < 0)
+		                           BASR_ACK, 0) < 0)
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
-- 
2.29.2


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v3] scsi: NCR5380: Remove context check
  2020-12-06  7:51     ` [PATCH v3] " Ahmed S. Darwish
@ 2020-12-08  0:12       ` Finn Thain
  2020-12-08  1:26       ` Martin K. Petersen
  2020-12-09 17:23       ` Martin K. Petersen
  2 siblings, 0 replies; 12+ messages in thread
From: Finn Thain @ 2020-12-08  0:12 UTC (permalink / raw)
  To: Ahmed S. Darwish
  Cc: Michael Schmitz, Geert Uytterhoeven, James E.J. Bottomley,
	Martin K. Petersen, Sebastian A. Siewior, Thomas Gleixner,
	linux-scsi, linux-kernel

On Sun, 6 Dec 2020, Ahmed S. Darwish wrote:

> NCR5380_poll_politely2() uses in_interrupt() and irqs_disabled() to
> check if it is safe to sleep.
> 
> Such usage in drivers is phased out and Linus clearly requested that
> code which changes behaviour depending on context should either be
> separated, or the context be explicitly conveyed in an argument passed
> by the caller.
> 
> Below is a context analysis of NCR5380_poll_politely2() uppermost
> callers:
> 
>   - NCR5380_maybe_reset_bus(), task, invoked during device probe.
>     -> NCR5380_poll_politely()
>     -> do_abort()
> 
>   - NCR5380_select(), task, but can only sleep in the "release, then
>     re-acquire" regions of the spinlock held by its caller.
>     Sleeping invocations (lock released):
>     -> NCR5380_poll_politely2()
> 
>     Atomic invocations (lock acquired):
>     -> NCR5380_reselect()
>        -> NCR5380_poll_politely()
>        -> do_abort()
>        -> NCR5380_transfer_pio()
> 
>   - NCR5380_intr(), interrupt handler
>     -> NCR5380_dma_complete()
>        -> NCR5380_transfer_pio()
> 	  -> NCR5380_poll_politely()
>     -> NCR5380_reselect() (see above)
> 
>   - NCR5380_information_transfer(), task, but can only sleep in the
>     "release, then re-acquire" regions of the caller-held spinlock.
>     Sleeping invocations (lock released):
>       - NCR5380_transfer_pio() -> NCR5380_poll_politely()
>       - NCR5380_poll_politely()
> 
>     Atomic invocations (lock acquired):
>       - NCR5380_transfer_dma()
> 	-> NCR5380_dma_recv_setup()
>            => generic_NCR5380_precv() -> NCR5380_poll_politely()
> 	   => macscsi_pread() -> NCR5380_poll_politely()
> 
> 	-> NCR5380_dma_send_setup()
>  	   => generic_NCR5380_psend -> NCR5380_poll_politely2()
> 	   => macscsi_pwrite() -> NCR5380_poll_politely()
> 
> 	-> NCR5380_poll_politely2()
>         -> NCR5380_dma_complete()
>            -> NCR5380_transfer_pio()
> 	      -> NCR5380_poll_politely()
>       - NCR5380_transfer_pio() -> NCR5380_poll_politely
> 
>   - NCR5380_reselect(), atomic, always called with hostdata spinlock
>     held.
> 
> Since NCR5380_poll_politely2() already takes a "wait" argument in
> jiffies, use it to determine if the function can sleep. Modify atomic
> callers, which passed an unused wait value in terms of HZ, to pass zero.
> 
> Suggested-by: Finn Thain <fthain@telegraphics.com.au>
> Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Cc: Michael Schmitz <schmitzmic@gmail.com>
> Cc: <linux-m68k@lists.linux-m68k.org>

Acked-by: Finn Thain <fthain@telegraphics.com.au>

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v3] scsi: NCR5380: Remove context check
  2020-12-06  7:51     ` [PATCH v3] " Ahmed S. Darwish
  2020-12-08  0:12       ` Finn Thain
@ 2020-12-08  1:26       ` Martin K. Petersen
  2020-12-09 17:23       ` Martin K. Petersen
  2 siblings, 0 replies; 12+ messages in thread
From: Martin K. Petersen @ 2020-12-08  1:26 UTC (permalink / raw)
  To: Ahmed S. Darwish
  Cc: Finn Thain, Michael Schmitz, Geert Uytterhoeven,
	James E.J. Bottomley, Martin K. Petersen, Sebastian A. Siewior,
	Thomas Gleixner, linux-scsi, linux-kernel


Ahmed,

> NCR5380_poll_politely2() uses in_interrupt() and irqs_disabled() to
> check if it is safe to sleep.

Applied to 5.11/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v3] scsi: NCR5380: Remove context check
  2020-12-06  7:51     ` [PATCH v3] " Ahmed S. Darwish
  2020-12-08  0:12       ` Finn Thain
  2020-12-08  1:26       ` Martin K. Petersen
@ 2020-12-09 17:23       ` Martin K. Petersen
  2 siblings, 0 replies; 12+ messages in thread
From: Martin K. Petersen @ 2020-12-09 17:23 UTC (permalink / raw)
  To: Ahmed S. Darwish, Finn Thain
  Cc: Martin K . Petersen, James E.J. Bottomley, Sebastian A. Siewior,
	Geert Uytterhoeven, linux-kernel, Thomas Gleixner,
	Michael Schmitz, linux-scsi

On Sun, 6 Dec 2020 08:51:57 +0100, Ahmed S. Darwish wrote:

> NCR5380_poll_politely2() uses in_interrupt() and irqs_disabled() to
> check if it is safe to sleep.
> 
> Such usage in drivers is phased out and Linus clearly requested that
> code which changes behaviour depending on context should either be
> separated, or the context be explicitly conveyed in an argument passed
> by the caller.
> 
> [...]

Applied to 5.11/scsi-queue, thanks!

[1/1] scsi: NCR5380: Remove context check
      https://git.kernel.org/mkp/scsi/c/e7734ef14ead

-- 
Martin K. Petersen	Oracle Linux Engineering

^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, back to index

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-01  6:46 [PATCH] scsi/NCR5380: Remove in_interrupt() test Finn Thain
2020-12-01 17:05 ` Sebastian Andrzej Siewior
2020-12-03 23:08   ` Finn Thain
2020-12-04  8:38     ` Geert Uytterhoeven
2020-12-04 16:08     ` Ahmed S. Darwish
2020-12-01 18:01 ` Michael Schmitz
2020-12-04 15:32 ` [PATCH v2] scsi: NCR5380: Remove context check Ahmed S. Darwish
2020-12-05  4:28   ` Finn Thain
2020-12-06  7:51     ` [PATCH v3] " Ahmed S. Darwish
2020-12-08  0:12       ` Finn Thain
2020-12-08  1:26       ` Martin K. Petersen
2020-12-09 17:23       ` Martin K. Petersen

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