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From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
To: "James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Christoph Hellwig <hch@infradead.org>,
	John Garry <john.garry@huawei.com>,
	Jason Yan <yanaijie@huawei.com>, Daniel Wagner <dwagner@suse.de>,
	Artur Paszkiewicz <artur.paszkiewicz@intel.com>,
	Jack Wang <jinpu.wang@cloud.ionos.com>
Cc: linux-scsi@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Sebastian A. Siewior" <bigeasy@linutronix.de>,
	"Ahmed S. Darwish" <a.darwish@linutronix.de>
Subject: [PATCH v3 05/19] scsi: isci: port: link down: Pass gfp_t flags
Date: Mon, 18 Jan 2021 11:09:41 +0100	[thread overview]
Message-ID: <20210118100955.1761652-6-a.darwish@linutronix.de> (raw)
In-Reply-To: <20210118100955.1761652-1-a.darwish@linutronix.de>

Use the new libsas event notifiers API, which requires callers to
explicitly pass the gfp_t memory allocation flags.

sas_notify_phy_event() is exclusively called by isci_port_link_down().
Below is the context analysis for all of its call chains:

port.c: port_timeout(), atomic, timer callback                  (*)
spin_lock_irqsave(isci_host::scic_lock, )
  -> port_state_machine_change(..., SCI_PORT_FAILED)
    -> enter SCI port state: *SCI_PORT_FAILED*
      -> sci_port_failed_state_enter()
        -> isci_port_hard_reset_complete()
          -> isci_port_link_down()

port.c: isci_port_perform_hard_reset()
spin_lock_irqsave(isci_host::scic_lock, )
  -> port.c: sci_port_hard_reset(), atomic                      (*)
    -> phy.c: sci_phy_reset()
      -> sci_change_state(SCI_PHY_RESETTING)
        -> enter SCI PHY state: *SCI_PHY_RESETTING*
          -> sci_phy_resetting_state_enter()
            -> port.c: sci_port_deactivate_phy()
	      -> isci_port_link_down()

port.c: enter SCI port state: *SCI_PORT_READY*                  # Cont. from [1]
  -> sci_port_ready_state_enter()
    -> isci_port_hard_reset_complete()
      -> isci_port_link_down()

phy.c: enter SCI state: *SCI_PHY_STOPPED*                       # Cont. from [2]
  -> sci_phy_stopped_state_enter()
    -> host.c: sci_controller_link_down()
      -> ->link_down_handler()
      == port_config.c: sci_apc_agent_link_down()
        -> port.c: sci_port_remove_phy()
          -> sci_port_deactivate_phy()
            -> isci_port_link_down()
      == port_config.c: sci_mpc_agent_link_down()
        -> port.c: sci_port_link_down()
          -> sci_port_deactivate_phy()
            -> isci_port_link_down()

phy.c: enter SCI state: *SCI_PHY_STARTING*                      # Cont. from [3]
  -> sci_phy_starting_state_enter()
    -> host.c: sci_controller_link_down()
      -> ->link_down_handler()
      == port_config.c: sci_apc_agent_link_down()
        -> port.c: sci_port_remove_phy()
          -> isci_port_link_down()
      == port_config.c: sci_mpc_agent_link_down()
        -> port.c: sci_port_link_down()
          -> sci_port_deactivate_phy()
            -> isci_port_link_down()

[1] Call chains for 'enter SCI port state: *SCI_PORT_READY*'
------------------------------------------------------------

host.c: isci_host_init()                                        (@)
spin_lock_irq(isci_host::scic_lock)
  -> sci_controller_initialize(), atomic                        (*)
    -> port_config.c: sci_port_configuration_agent_initialize()
      -> sci_mpc_agent_validate_phy_configuration()
        -> port.c: sci_port_add_phy()
          -> sci_port_general_link_up_handler()
            -> port_state_machine_change(, SCI_PORT_READY)
              -> enter port state *SCI_PORT_READY*

host.c: isci_host_start()                                       (@)
spin_lock_irq(isci_host::scic_lock)
  -> host.c: sci_controller_start(), atomic                     (*)
    -> host.c: sci_port_start()
      -> port.c: port_state_machine_change(, SCI_PORT_READY)
        -> enter port state *SCI_PORT_READY*

port_config.c: apc_agent_timeout(), atomic, timer callback      (*)
  -> sci_apc_agent_configure_ports()
    -> port.c: sci_port_add_phy()
      -> sci_port_general_link_up_handler()
        -> port_state_machine_change(, SCI_PORT_READY)
          -> enter port state *SCI_PORT_READY*

port_config.c: mpc_agent_timeout(), atomic, timer callback      (*)
spin_lock_irqsave(isci_host::scic_lock, )
  -> ->link_up_handler()
  == port.c: sci_apc_agent_link_up()
    -> sci_port_general_link_up_handler()
      -> port_state_machine_change(, SCI_PORT_READY)
        -> enter port state *SCI_PORT_READY*
  == port.c: sci_mpc_agent_link_up()
    -> port.c: sci_port_link_up()
      -> sci_port_general_link_up_handler()
        -> port_state_machine_change(, SCI_PORT_READY)
          -> enter port state *SCI_PORT_READY*

phy.c: enter SCI state: SCI_PHY_SUB_FINAL                       # Cont. from [1A]
  -> sci_phy_starting_final_substate_enter()
    -> sci_change_state(SCI_PHY_READY)
      -> enter SCI state: *SCI_PHY_READY*
        -> sci_phy_ready_state_enter()
          -> host.c: sci_controller_link_up()
            -> port_agent.link_up_handler()
            == port_config.c: sci_apc_agent_link_up()
              -> port.c: sci_port_link_up()
                -> sci_port_general_link_up_handler()
                  -> port_state_machine_change(, SCI_PORT_READY)
                    -> enter port state *SCI_PORT_READY*
            == port_config.c: sci_mpc_agent_link_up()
              -> port.c: sci_port_link_up()
                -> sci_port_general_link_up_handler()
                  -> port_state_machine_change(, SCI_PORT_READY)
                    -> enter port state *SCI_PORT_READY*

[1A] Call chains for entering SCI state: *SCI_PHY_SUB_FINAL*
------------------------------------------------------------

host.c: power_control_timeout(), atomic, timer callback         (*)
spin_lock_irqsave(isci_host::scic_lock, )
  -> phy.c: sci_phy_consume_power_handler()
    -> phy.c: sci_change_state(SCI_PHY_SUB_FINAL)

host.c: sci_controller_error_handler(): atomic, irq handler     (*)
OR host.c: sci_controller_completion_handler(), atomic, tasklet (*)
  -> sci_controller_process_completions()
    -> sci_controller_unsolicited_frame()
      -> phy.c: sci_phy_frame_handler()
        -> sci_change_state(SCI_PHY_SUB_AWAIT_SAS_POWER)
          -> sci_phy_starting_await_sas_power_substate_enter()
            -> host.c: sci_controller_power_control_queue_insert()
              -> phy.c: sci_phy_consume_power_handler()
                -> sci_change_state(SCI_PHY_SUB_FINAL)
        -> sci_change_state(SCI_PHY_SUB_FINAL)
    -> sci_controller_event_completion()
      -> phy.c: sci_phy_event_handler()
        -> sci_phy_start_sata_link_training()
          -> sci_change_state(SCI_PHY_SUB_AWAIT_SATA_POWER)
            -> sci_phy_starting_await_sata_power_substate_enter
              -> host.c: sci_controller_power_control_queue_insert()
                -> phy.c: sci_phy_consume_power_handler()
                  -> sci_change_state(SCI_PHY_SUB_FINAL)

[2] Call chains for entering state: *SCI_PHY_STOPPED*
-----------------------------------------------------

host.c: isci_host_init()                                        (@)
spin_lock_irq(isci_host::scic_lock)
  -> sci_controller_initialize(), atomic                        (*)
      -> phy.c: sci_phy_initialize()
        -> phy.c: sci_phy_link_layer_initialization()
          -> phy.c: sci_change_state(SCI_PHY_STOPPED)

init.c: PCI ->remove() || PM_OPS ->suspend,  process context    (+)
  -> host.c: isci_host_deinit()
    -> sci_controller_stop_phys()
      -> phy.c: sci_phy_stop()
	-> sci_change_state(SCI_PHY_STOPPED)

phy.c: isci_phy_control()
spin_lock_irqsave(isci_host::scic_lock, )
  -> sci_phy_stop(), atomic                                     (*)
    -> sci_change_state(SCI_PHY_STOPPED)

[3] Call chains for entering state: *SCI_PHY_STARTING*
------------------------------------------------------

phy.c: phy_sata_timeout(), atimer, timer callback               (*)
spin_lock_irqsave(isci_host::scic_lock, )
  -> sci_change_state(SCI_PHY_STARTING)

host.c: phy_startup_timeout(), atomic, timer callback           (*)
spin_lock_irqsave(isci_host::scic_lock, )
  -> sci_controller_start_next_phy()
    -> sci_phy_start()
      -> sci_change_state(SCI_PHY_STARTING)

host.c: isci_host_start()                                       (@)
spin_lock_irq(isci_host::scic_lock)
  -> sci_controller_start(), atomic                             (*)
    -> sci_controller_start_next_phy()
      -> sci_phy_start()
        -> sci_change_state(SCI_PHY_STARTING)

phy.c: Enter SCI state *SCI_PHY_SUB_FINAL*, atomic, check above (*)
  -> sci_change_state(SCI_PHY_SUB_FINAL)
    -> sci_phy_starting_final_substate_enter()
      -> sci_change_state(SCI_PHY_READY)
        -> Enter SCI state: *SCI_PHY_READY*
          -> sci_phy_ready_state_enter()
            -> host.c: sci_controller_link_up()
              -> sci_controller_start_next_phy()
                -> sci_phy_start()
                  -> sci_change_state(SCI_PHY_STARTING)

phy.c: sci_phy_event_handler(), atomic, discussed earlier       (*)
  -> sci_change_state(SCI_PHY_STARTING), 11 instances

phy.c: enter SCI state: *SCI_PHY_RESETTING*, atomic, discussed  (*)
  -> sci_phy_resetting_state_enter()
    -> sci_change_state(SCI_PHY_STARTING)

As can be seen from the "(*)" markers above, almost all the call-chains
are atomic. The only exception, marked with "(+)", is a PCI ->remove()
and PM_OPS ->suspend() cold path. Thus, pass GFP_ATOMIC to the libsas
phy event notifier.

Note, The now-replaced libsas APIs used in_interrupt() to implicitly
decide which memory allocation type to use.  This was only partially
correct, as it fails to choose the correct GFP flags when just
preemption or interrupts are disabled. Such buggy code paths are marked
with "(@)" in the call chains above.

Fixes: 1c393b970e0f ("scsi: libsas: Use dynamic alloced work to avoid sas event lost")
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Reviewed-by: John Garry <john.garry@huawei.com>
Cc: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
 drivers/scsi/isci/port.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/isci/port.c b/drivers/scsi/isci/port.c
index 8d9349738067..a3c58718c260 100644
--- a/drivers/scsi/isci/port.c
+++ b/drivers/scsi/isci/port.c
@@ -269,8 +269,8 @@ static void isci_port_link_down(struct isci_host *isci_host,
 	 * isci_port_deformed and isci_dev_gone functions.
 	 */
 	sas_phy_disconnected(&isci_phy->sas_phy);
-	sas_notify_phy_event(&isci_phy->sas_phy,
-					   PHYE_LOSS_OF_SIGNAL);
+	sas_notify_phy_event_gfp(&isci_phy->sas_phy,
+				 PHYE_LOSS_OF_SIGNAL, GFP_ATOMIC);
 
 	dev_dbg(&isci_host->pdev->dev,
 		"%s: isci_port = %p - Done\n", __func__, isci_port);
-- 
2.30.0


  parent reply	other threads:[~2021-01-18 21:30 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-18 10:09 [PATCH v3 00/19] scsi: libsas: Remove in_interrupt() check Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 01/19] Documentation: scsi: libsas: Remove notify_ha_event() Ahmed S. Darwish
2021-01-18 10:22   ` Jinpu Wang
2021-01-18 10:09 ` [PATCH v3 02/19] scsi: libsas and users: Remove notifier indirection Ahmed S. Darwish
2021-01-18 10:26   ` Jinpu Wang
2021-01-18 10:09 ` [PATCH v3 03/19] scsi: libsas: Introduce a _gfp() variant of event notifiers Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 04/19] scsi: mvsas: Pass gfp_t flags to libsas " Ahmed S. Darwish
2021-01-18 10:09 ` Ahmed S. Darwish [this message]
2021-01-18 10:09 ` [PATCH v3 06/19] scsi: isci: port: link up: Pass gfp_t flags Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 07/19] scsi: isci: port: broadcast change: " Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 08/19] scsi: libsas: Pass gfp_t flags to event notifiers Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 09/19] scsi: pm80xx: Pass gfp_t flags to libsas " Ahmed S. Darwish
2021-01-18 10:26   ` Jinpu Wang
2021-01-18 10:09 ` [PATCH v3 10/19] scsi: aic94xx: " Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 11/19] scsi: hisi_sas: " Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 12/19] scsi: libsas: event notifiers API: Add gfp_t flags parameter Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 13/19] scsi: hisi_sas: Switch back to original libsas event notifiers Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 14/19] scsi: aic94xx: " Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 15/19] scsi: pm80xx: " Ahmed S. Darwish
2021-01-18 10:27   ` Jinpu Wang
2021-01-18 10:09 ` [PATCH v3 16/19] scsi: libsas: Switch back to original event notifiers API Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 17/19] scsi: isci: Switch back to original libsas event notifiers Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 18/19] scsi: mvsas: " Ahmed S. Darwish
2021-01-18 10:09 ` [PATCH v3 19/19] scsi: libsas: Remove temporarily-added _gfp() API variants Ahmed S. Darwish
2021-01-23  2:32 ` [PATCH v3 00/19] scsi: libsas: Remove in_interrupt() check Martin K. Petersen
2021-01-27  4:54 ` Martin K. Petersen

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