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From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 12/15] tty: hvc: hvc_poll may sleep
Date: Tue,  1 May 2018 00:55:55 +1000	[thread overview]
Message-ID: <20180430145558.4308-13-npiggin@gmail.com> (raw)
In-Reply-To: <20180430145558.4308-1-npiggin@gmail.com>

Introduce points where hvc_poll drops the lock, enables interrupts,
and reschedules.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 drivers/tty/hvc/hvc_console.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index 745ac220fce8..2abfc0b15fbb 100644
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -589,7 +589,7 @@ static u32 timeout = MIN_TIMEOUT;
 #define HVC_POLL_READ	0x00000001
 #define HVC_POLL_WRITE	0x00000002
 
-int hvc_poll(struct hvc_struct *hp)
+static int __hvc_poll(struct hvc_struct *hp, bool may_sleep)
 {
 	struct tty_struct *tty;
 	int i, n, count, poll_mask = 0;
@@ -611,6 +611,12 @@ int hvc_poll(struct hvc_struct *hp)
 		timeout = (written_total) ? 0 : MIN_TIMEOUT;
 	}
 
+	if (may_sleep) {
+		spin_unlock_irqrestore(&hp->lock, flags);
+		cond_resched();
+		spin_lock_irqsave(&hp->lock, flags);
+	}
+
 	/* No tty attached, just skip */
 	tty = tty_port_tty_get(&hp->port);
 	if (tty == NULL)
@@ -698,6 +704,11 @@ int hvc_poll(struct hvc_struct *hp)
 
 	return poll_mask;
 }
+
+int hvc_poll(struct hvc_struct *hp)
+{
+	return __hvc_poll(hp, false);
+}
 EXPORT_SYMBOL_GPL(hvc_poll);
 
 /**
@@ -736,7 +747,8 @@ static int khvcd(void *unused)
 		if (!cpus_are_in_xmon()) {
 			mutex_lock(&hvc_structs_mutex);
 			list_for_each_entry(hp, &hvc_structs, next) {
-				poll_mask |= hvc_poll(hp);
+				poll_mask |= __hvc_poll(hp, true);
+				cond_resched();
 			}
 			mutex_unlock(&hvc_structs_mutex);
 		} else
-- 
2.17.0

  parent reply	other threads:[~2018-04-30 14:55 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 14:55 [PATCH 00/15] hvc and powerpc opal console latency reduction Nicholas Piggin
2018-04-30 14:55 ` [PATCH 01/15] powerpc/powernv: opal_put_chars partial write fix Nicholas Piggin
2018-07-24 13:59   ` [01/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 02/15] powerpc/powernv: Fix OPAL console driver OPAL_BUSY loops Nicholas Piggin
2018-04-30 14:55 ` [PATCH 03/15] powerpc/powernv: opal-kmsg standardise OPAL_BUSY handling Nicholas Piggin
2018-04-30 14:55 ` [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback from console code Nicholas Piggin
2018-05-04  5:16   ` Michael Ellerman
2018-05-04  5:37     ` Nicholas Piggin
2018-05-07 10:36       ` Michael Ellerman
2018-05-08  3:40         ` Nicholas Piggin
2018-04-30 14:55 ` [PATCH 05/15] powerpc/powernv: Implement and use opal_flush_console Nicholas Piggin
2018-04-30 14:55 ` [PATCH 06/15] powerpc/powernv: Remove OPALv1 support from opal console driver Nicholas Piggin
2018-04-30 14:55 ` [PATCH 07/15] powerpc/powernv: move opal console flushing to udbg Nicholas Piggin
2018-04-30 14:55 ` [PATCH 08/15] powerpc/powernv: implement opal_put_chars_atomic Nicholas Piggin
2018-05-01  9:48   ` Benjamin Herrenschmidt
2018-05-01 10:37     ` Nicholas Piggin
2018-05-07 10:35       ` Michael Ellerman
2018-05-08  3:36         ` Nicholas Piggin
2018-04-30 14:55 ` [PATCH 09/15] tty: hvc: remove unexplained "just in case" spin delay Nicholas Piggin
2018-04-30 14:55 ` [PATCH 10/15] tty: hvc: use mutex instead of spinlock for hvc_structs lock Nicholas Piggin
2018-08-13 11:22   ` [10/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 11/15] tty: hvc: hvc_poll break hv read loop Nicholas Piggin
2018-08-13 11:23   ` [11/15] " Michael Ellerman
2018-04-30 14:55 ` Nicholas Piggin [this message]
2018-08-13 11:23   ` [12/15] tty: hvc: hvc_poll may sleep Michael Ellerman
2018-04-30 14:55 ` [PATCH 13/15] tty: hvc: hvc_write " Nicholas Piggin
2018-08-13 11:23   ` [13/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 14/15] tty: hvc: introduce the hv_ops.flush operation for hvc drivers Nicholas Piggin
2018-08-13 11:23   ` [14/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 15/15] powerpc/powernv: provide a console flush operation for opal hvc driver Nicholas Piggin
2018-08-21 10:35   ` [15/15] " Michael Ellerman

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