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 --- include/scsi/libsas.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/scsi/libsas.h') diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h index 8e402d5a0640..42900fa95a03 100644 --- a/include/scsi/libsas.h +++ b/include/scsi/libsas.h @@ -330,6 +330,7 @@ struct sas_ha_event { enum sas_ha_state { SAS_HA_REGISTERED, + SAS_HA_DRAINING, }; struct sas_ha_struct { @@ -337,6 +338,8 @@ struct sas_ha_struct { struct sas_ha_event ha_events[HA_NUM_EVENTS]; unsigned long pending; + struct list_head defer_q; /* work queued while draining */ + struct mutex drain_mutex; unsigned long state; spinlock_t state_lock; @@ -657,6 +660,7 @@ int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd); extern void sas_target_destroy(struct scsi_target *); extern int sas_slave_alloc(struct scsi_device *); extern int sas_ioctl(struct scsi_device *sdev, int cmd, void __user *arg); +extern int sas_drain_work(struct sas_ha_struct *ha); extern int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy, struct request *req); -- cgit v1.2.3