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authorDan Williams <dan.j.williams@intel.com>2011-12-20 04:42:34 +0400
committerJames Bottomley <JBottomley@Parallels.com>2012-02-19 23:48:51 +0400
commitb1124cd3ec97406c767b90bf7e93ecd2d2915592 (patch)
treed0936775aacff4492177c14a73175738dfb51ee0 /include/scsi
parentf8daa6e6d83f60a721752cb53433bfdc1503b45f (diff)
downloadlinux-b1124cd3ec97406c767b90bf7e93ecd2d2915592.tar.xz
[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 <dan.j.williams@intel.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'include/scsi')
-rw-r--r--include/scsi/libsas.h4
1 files changed, 4 insertions, 0 deletions
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);