megaraid: fix BUG_ON() from incorrect use of delayed work

megaraid use INIT_WORK to declare a hotplug_work, but cast the
hotplug_work from work_struct to delayed_work and
schedule_delayed_work on it.  This is very dangerous, as other part of
delayed_work might be kernel memories allocated by others.

With commit 8852aac ("workqueue: mod_delayed_work_on() shouldn't queue
timer on 0 delay"), schedule_delayed_work() will check dwork->timer
before queue_work even when @delay is 0, this causes megaraid code to
hit the BUG_ON() in workqueue code.  Change megaraid code to use
delayed work.

Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Neela Syam Kolli <megaraidlinux@lsi.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: linux-scsi@vger.kernel.org

2 files changed, 7 insertions, 9 deletions

diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index 16b7a72a70c4..3b2365c8eab2 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -1276,7 +1276,7 @@ struct megasas_evt_detail {
 } __attribute__ ((packed));
 
 struct megasas_aen_event {
-        struct work_struct hotplug_work;
+        struct delayed_work hotplug_work;
         struct megasas_instance *instance;
 };
 
diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index d2c5366aff7f..e4f2baacf1e1 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -2060,9 +2060,9 @@ megasas_service_aen(struct megasas_instance *instance, struct megasas_cmd *cmd)
                 } else {
                         ev->instance = instance;
                         instance->ev = ev;
-                        INIT_WORK(&ev->hotplug_work, megasas_aen_polling);
-                        schedule_delayed_work(
-                                (struct delayed_work *)&ev->hotplug_work, 0);
+                        INIT_DELAYED_WORK(&ev->hotplug_work,
+                                          megasas_aen_polling);
+                        schedule_delayed_work(&ev->hotplug_work, 0);
                 }
         }
 }
@@ -4352,8 +4352,7 @@ megasas_suspend(struct pci_dev *pdev, pm_message_t state)
         /* cancel the delayed work if this work still in queue */
         if (instance->ev != NULL) {
                 struct megasas_aen_event *ev = instance->ev;
-                cancel_delayed_work_sync(
-                        (struct delayed_work *)&ev->hotplug_work);
+                cancel_delayed_work_sync(&ev->hotplug_work);
                 instance->ev = NULL;
         }
 
@@ -4545,8 +4544,7 @@ static void __devexit megasas_detach_one(struct pci_dev *pdev)
         /* cancel the delayed work if this work still in queue*/
         if (instance->ev != NULL) {
                 struct megasas_aen_event *ev = instance->ev;
-                cancel_delayed_work_sync(
-                        (struct delayed_work *)&ev->hotplug_work);
+                cancel_delayed_work_sync(&ev->hotplug_work);
                 instance->ev = NULL;
         }
 
@@ -5190,7 +5188,7 @@ static void
 megasas_aen_polling(struct work_struct *work)
 {
         struct megasas_aen_event *ev =
-                container_of(work, struct megasas_aen_event, hotplug_work);
+                container_of(work, struct megasas_aen_event, hotplug_work.work);
         struct megasas_instance *instance = ev->instance;
         union megasas_evt_class_locale class_locale;
         struct  Scsi_Host *host;