Commit 307d9f49 authored by Xiang Chen's avatar Xiang Chen Committed by Martin K. Petersen
Browse files

scsi: libsas: Keep host active while processing events 

Processing events such as PORTE_BROADCAST_RCVD may cause dependency issues
for runtime power management support.  Such a problem would be that
handling a PORTE_BROADCAST_RCVD event requires that the host is resumed to
send SMP commands. However, in resuming the host, the phyup events
generated from re-enabling the phys are processed in the same workqueue as
the original PORTE_BROADCAST_RCVD event. As such, the host will never
finish resuming (as it waits for the phyup event processing), and then the
PORTE_BROADCAST_RCVD event can't be processed as the SMP commands are
blocked, and so we have a deadlock.  Solve this problem by ensuring that
libsas keeps the host active until completely finished phy or port events,
such as PORTE_BYTES_DMAED. As such, we don't have to worry about resuming
the host for processing individual SMP commands in this example.

Link: https://lore.kernel.org/r/1639999298-244569-15-git-send-email-chenxiang66@hisilicon.com


Reviewed-by: default avatarJohn Garry <john.garry@huawei.com>
Signed-off-by: default avatarXiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent ae9b69e8

drivers/scsi/libsas/sas_event.c

+21 −3
Original line number Diff line number Diff line
@@ -50,9 +50,11 @@ void sas_queue_deferred_work(struct sas_ha_struct *ha) 
	list_for_each_entry_safe(sw, _sw, &ha->defer_q, drain_node) {

		list_del_init(&sw->drain_node);

		ret = sas_queue_work(ha, sw);

		if (ret != 1)

		if (ret != 1) {

			pm_runtime_put(ha->dev);

			sas_free_event(to_asd_sas_event(&sw->work));

		}

	}

	spin_unlock_irq(&ha->lock);

}
@@ -126,16 +128,22 @@ void sas_enable_revalidation(struct sas_ha_struct *ha) 
static void sas_port_event_worker(struct work_struct *work)

{

	struct asd_sas_event *ev = to_asd_sas_event(work);

	struct asd_sas_phy *phy = ev->phy;

	struct sas_ha_struct *ha = phy->ha;



	sas_port_event_fns[ev->event](work);

	pm_runtime_put(ha->dev);

	sas_free_event(ev);

}



static void sas_phy_event_worker(struct work_struct *work)

{

	struct asd_sas_event *ev = to_asd_sas_event(work);

	struct asd_sas_phy *phy = ev->phy;

	struct sas_ha_struct *ha = phy->ha;



	sas_phy_event_fns[ev->event](work);

	pm_runtime_put(ha->dev);

	sas_free_event(ev);

}
@@ -170,14 +178,19 @@ int sas_notify_port_event(struct asd_sas_phy *phy, enum port_event event, 
	if (!ev)

		return -ENOMEM;



	/* Call pm_runtime_put() with pairs in sas_port_event_worker() */

	pm_runtime_get_noresume(ha->dev);



	INIT_SAS_EVENT(ev, sas_port_event_worker, phy, event);



	if (sas_defer_event(phy, ev))

		return 0;



	ret = sas_queue_event(event, &ev->work, ha);

	if (ret != 1)

	if (ret != 1) {

		pm_runtime_put(ha->dev);

		sas_free_event(ev);

	}



	return ret;

}
@@ -196,14 +209,19 @@ int sas_notify_phy_event(struct asd_sas_phy *phy, enum phy_event event, 
	if (!ev)

		return -ENOMEM;



	/* Call pm_runtime_put() with pairs in sas_phy_event_worker() */

	pm_runtime_get_noresume(ha->dev);



	INIT_SAS_EVENT(ev, sas_phy_event_worker, phy, event);



	if (sas_defer_event(phy, ev))

		return 0;



	ret = sas_queue_event(event, &ev->work, ha);

	if (ret != 1)

	if (ret != 1) {

		pm_runtime_put(ha->dev);

		sas_free_event(ev);

	}



	return ret;

}