From b1124cd3ec97406c767b90bf7e93ecd2d2915592 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 19 Dec 2011 16:42:34 -0800 Subject: [SCSI] libsas: introduce sas_drain_work() When an lldd invokes ->notify_port_event() it can trigger a chain of libsas events to: 1/ form the port and find the direct attached device 2/ if the attached device is an expander perform domain discovery A call to flush_workqueue() will only flush the initial port formation work. Currently libsas users need to call scsi_flush_work() up to the max depth of chain (which will grow from 2 to 3 when ata discovery is moved to its own discovery event). Instead of open coding multiple calls switch to use drain_workqueue() to flush sas work. drain_workqueue() does not handle new work submitted during the drain so libsas needs a bit of infrastructure to hold off unchained work submissions while a drain is in flight. A lldd ->notify() event is considered 'unchained' while a sas_discover_event() is 'chained'. As Tejun notes: "For now, I think it would be best to add private wrapper in libsas to support deferring unchained work items while draining." Signed-off-by: Dan Williams Signed-off-by: James Bottomley --- drivers/scsi/libsas/sas_init.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'drivers/scsi/libsas/sas_init.c') diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c index da244e68fe6f..572b943d7603 100644 --- a/drivers/scsi/libsas/sas_init.c +++ b/drivers/scsi/libsas/sas_init.c @@ -114,6 +114,8 @@ int sas_register_ha(struct sas_ha_struct *sas_ha) set_bit(SAS_HA_REGISTERED, &sas_ha->state); spin_lock_init(&sas_ha->state_lock); + mutex_init(&sas_ha->drain_mutex); + INIT_LIST_HEAD(&sas_ha->defer_q); error = sas_register_phys(sas_ha); if (error) { @@ -157,12 +159,13 @@ int sas_unregister_ha(struct sas_ha_struct *sas_ha) { unsigned long flags; - /* Set the state to unregistered to avoid further - * events to be queued */ + /* Set the state to unregistered to avoid further unchained + * events to be queued + */ spin_lock_irqsave(&sas_ha->state_lock, flags); clear_bit(SAS_HA_REGISTERED, &sas_ha->state); spin_unlock_irqrestore(&sas_ha->state_lock, flags); - scsi_flush_work(sas_ha->core.shost); + sas_drain_work(sas_ha); sas_unregister_ports(sas_ha); -- cgit v1.2.3