[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>

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 120bff64be30..10cb5ae30977 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -94,8 +94,7 @@ void sas_hash_addr(u8 *hashed, const u8 *sas_addr)
 
 void sas_hae_reset(struct work_struct *work)
 {
-	struct sas_ha_event *ev =
-		container_of(work, struct sas_ha_event, work);
+	struct sas_ha_event *ev = to_sas_ha_event(work);
 	struct sas_ha_struct *ha = ev->ha;
 
 	clear_bit(HAE_RESET, &ha->pending);
@@ -369,14 +368,14 @@ static void sas_phy_release(struct sas_phy *phy)
 
 static void phy_reset_work(struct work_struct *work)
 {
-	struct sas_phy_data *d = container_of(work, typeof(*d), reset_work);
+	struct sas_phy_data *d = container_of(work, typeof(*d), reset_work.work);
 
 	d->reset_result = transport_sas_phy_reset(d->phy, d->hard_reset);
 }
 
 static void phy_enable_work(struct work_struct *work)
 {
-	struct sas_phy_data *d = container_of(work, typeof(*d), enable_work);
+	struct sas_phy_data *d = container_of(work, typeof(*d), enable_work.work);
 
 	d->enable_result = sas_phy_enable(d->phy, d->enable);
 }
@@ -389,8 +388,8 @@ static int sas_phy_setup(struct sas_phy *phy)
 		return -ENOMEM;
 
 	mutex_init(&d->event_lock);
-	INIT_WORK(&d->reset_work, phy_reset_work);
-	INIT_WORK(&d->enable_work, phy_enable_work);
+	INIT_SAS_WORK(&d->reset_work, phy_reset_work);
+	INIT_SAS_WORK(&d->enable_work, phy_enable_work);
 	d->phy = phy;
 	phy->hostdata = d;