commit 22b9153faa2263aa89625de25e71c7d44c8dbd16
author Dan Williams <dan.j.williams@intel.com> Fri Mar 09 11:00:06 2012 -0800
committer James Bottomley <JBottomley@Parallels.com> Mon Apr 23 12:03:39 2012 +0100
tree 1157d64a9c63c5b7b48b4a5b3610965d8d4c9624
parent f8fc75dc576eac0c996e4a792a4701819d999260

[SCSI] libsas: introduce sas_work to fix sas_drain_work vs sas_queue_work

When requeuing work to a draining workqueue the last work instance may
not be idle, so sas_queue_work() must not touch work->entry.  Introduce
sas_work with a drain_node list_head to have a private list for
collecting work deferred due to drain collision.

Fixes reports like:
  BUG: unable to handle kernel NULL pointer dereference at           (null)
  IP: [<ffffffff810410d4>] process_one_work+0x2e/0x338

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/libsas/sas_port.c

diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index eb19c01..1cf7d75 100644
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -208,8 +208,7 @@
 
 void sas_porte_bytes_dmaed(struct work_struct *work)
 {
-	struct asd_sas_event *ev =
-		container_of(work, struct asd_sas_event, work);
+	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 
 	clear_bit(PORTE_BYTES_DMAED, &phy->port_events_pending);
@@ -219,8 +218,7 @@
 
 void sas_porte_broadcast_rcvd(struct work_struct *work)
 {
-	struct asd_sas_event *ev =
-		container_of(work, struct asd_sas_event, work);
+	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 	unsigned long flags;
 	u32 prim;
@@ -237,8 +235,7 @@
 
 void sas_porte_link_reset_err(struct work_struct *work)
 {
-	struct asd_sas_event *ev =
-		container_of(work, struct asd_sas_event, work);
+	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 
 	clear_bit(PORTE_LINK_RESET_ERR, &phy->port_events_pending);
@@ -248,8 +245,7 @@
 
 void sas_porte_timer_event(struct work_struct *work)
 {
-	struct asd_sas_event *ev =
-		container_of(work, struct asd_sas_event, work);
+	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 
 	clear_bit(PORTE_TIMER_EVENT, &phy->port_events_pending);
@@ -259,8 +255,7 @@
 
 void sas_porte_hard_reset(struct work_struct *work)
 {
-	struct asd_sas_event *ev =
-		container_of(work, struct asd_sas_event, work);
+	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 
 	clear_bit(PORTE_HARD_RESET, &phy->port_events_pending);