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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>,
	Daniel Wagner <dwagner@suse.de>, Jason Yan <yanaijie@huawei.com>,
	John Garry <john.garry@huawei.com>,
	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 06/11] scsi: isci: port: broadcast change: Pass gfp_t flags
Date: Fri, 18 Dec 2020 21:43:49 +0100
Message-ID: <20201218204354.586951-7-a.darwish@linutronix.de> (raw)
In-Reply-To: <20201218204354.586951-1-a.darwish@linutronix.de>

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

The libsas ->notify_port_event() hook is called from
isci_port_bc_change_received(). Below is the context analysis for all of
its call chains:

host.c: sci_controller_error_handler(): atomic, irq handler     (*)
OR host.c: sci_controller_completion_handler(), atomic, tasklet (*)
  -> sci_controller_process_completions()
    -> sci_controller_event_completion()
      -> phy.c: sci_phy_event_handler()
        -> port.c: sci_port_broadcast_change_received()
          -> isci_port_bc_change_received()

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_set_phy()
            -> phy.c: sci_phy_set_port()
              -> port.c: sci_port_broadcast_change_received()
                -> isci_port_bc_change_received()

port_config.c: apc_agent_timeout(), atomic, timer callback      (*)
  -> sci_apc_agent_configure_ports()
    -> port.c: sci_port_add_phy()
      -> sci_port_set_phy()
        -> phy.c: sci_phy_set_port()
          -> port.c: sci_port_broadcast_change_received()
            -> isci_port_bc_change_received()

phy.c: enter SCI state: *SCI_PHY_STOPPED*                       # Cont. from [1]
  -> 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_clear_phy()
            -> phy.c: sci_phy_set_port()
              -> port.c: sci_port_broadcast_change_received()
                -> isci_port_bc_change_received()

phy.c: enter SCI state: *SCI_PHY_STARTING*                      # Cont. from [2]
  -> 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()
          -> sci_port_clear_phy()
            -> phy.c: sci_phy_set_port()
              -> port.c: sci_port_broadcast_change_received()
                -> isci_port_bc_change_received()

[1] 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)

[2] 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*                      # Cont. from [2A]
  -> 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

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()
            -> sci_change_state(SCI_PHY_STARTING)

[2A] 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)

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
port 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.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Cc: stable@vger.kernel.org
Cc: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
 drivers/scsi/isci/port.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/isci/port.c b/drivers/scsi/isci/port.c
index 69684c80c407..6244981a3ebf 100644
--- a/drivers/scsi/isci/port.c
+++ b/drivers/scsi/isci/port.c
@@ -164,7 +164,9 @@ static void isci_port_bc_change_received(struct isci_host *ihost,
 		"%s: isci_phy = %p, sas_phy = %p\n",
 		__func__, iphy, &iphy->sas_phy);
 
-	ihost->sas_ha.notify_port_event(&iphy->sas_phy, PORTE_BROADCAST_RCVD);
+	ihost->sas_ha.notify_port_event_gfp(&iphy->sas_phy,
+					    PORTE_BROADCAST_RCVD,
+					    GFP_ATOMIC);
 	sci_port_bcn_enable(iport);
 }
 
-- 
2.29.2


  parent reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-18 20:43 [PATCH 00/11] scsi: libsas: Remove in_interrupt() check Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 01/11] Documentation: scsi: libsas: Remove notify_ha_event() Ahmed S. Darwish
2020-12-21  9:10   ` John Garry
2020-12-18 20:43 ` [PATCH 02/11] scsi: libsas: Introduce a _gfp() variant of event notifiers Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 03/11] scsi: mvsas: Pass gfp_t flags to libsas " Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 04/11] scsi: isci: port: link down: Pass gfp_t flags Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 05/11] scsi: isci: port: link up: " Ahmed S. Darwish
2020-12-18 20:43 ` Ahmed S. Darwish [this message]
2020-12-18 20:43 ` [PATCH 07/11] scsi: libsas: Pass gfp_t flags to event notifiers Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 08/11] scsi: pm80xx: Pass gfp_t flags to libsas " Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 09/11] scsi: aic94xx: " Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 10/11] scsi: hisi_sas: " Ahmed S. Darwish
2020-12-18 20:43 ` [PATCH 11/11] scsi: libsas: event notifiers: Remove non _gfp() variants Ahmed S. Darwish
2020-12-21 17:17   ` John Garry
2020-12-21 17:38     ` Ahmed S. Darwish
2020-12-21 10:13 ` [PATCH 00/11] scsi: libsas: Remove in_interrupt() check John Garry
2020-12-22 12:30   ` Jason Yan
2020-12-22 12:54     ` John Garry
2021-01-11 13:43       ` Ahmed S. Darwish
2021-01-11 13:59         ` John Garry
2021-01-11 14:28           ` Ahmed S. Darwish

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