1 files changed, 45 insertions, 34 deletions

diff --git a/block/genhd.c b/block/genhd.c
index 95822ae25cf..3608289c8ec 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1371,6 +1371,7 @@ struct disk_events {
         struct gendisk          *disk;          /* the associated disk */
         spinlock_t              lock;
 
+        struct mutex            block_mutex;    /* protects blocking */
         int                     block;          /* event blocking depth */
         unsigned int            pending;        /* events already sent out */
         unsigned int            clearing;       /* events being cleared */
@@ -1414,22 +1415,44 @@ static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
         return msecs_to_jiffies(intv_msecs);
 }
 
-static void __disk_block_events(struct gendisk *disk, bool sync)
+/**
+ * disk_block_events - block and flush disk event checking
+ * @disk: disk to block events for
+ *
+ * On return from this function, it is guaranteed that event checking
+ * isn't in progress and won't happen until unblocked by
+ * disk_unblock_events().  Events blocking is counted and the actual
+ * unblocking happens after the matching number of unblocks are done.
+ *
+ * Note that this intentionally does not block event checking from
+ * disk_clear_events().
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void disk_block_events(struct gendisk *disk)
 {
         struct disk_events *ev = disk->ev;
         unsigned long flags;
         bool cancel;
 
+        if (!ev)
+                return;
+
+        /*
+         * Outer mutex ensures that the first blocker completes canceling
+         * the event work before further blockers are allowed to finish.
+         */
+        mutex_lock(&ev->block_mutex);
+
         spin_lock_irqsave(&ev->lock, flags);
         cancel = !ev->block++;
         spin_unlock_irqrestore(&ev->lock, flags);
 
-        if (cancel) {
-                if (sync)
-                        cancel_delayed_work_sync(&disk->ev->dwork);
-                else
-                        cancel_delayed_work(&disk->ev->dwork);
-        }
+        if (cancel)
+                cancel_delayed_work_sync(&disk->ev->dwork);
+
+        mutex_unlock(&ev->block_mutex);
 }
 
 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
@@ -1461,27 +1484,6 @@ out_unlock:
 }
 
 /**
- * disk_block_events - block and flush disk event checking
- * @disk: disk to block events for
- *
- * On return from this function, it is guaranteed that event checking
- * isn't in progress and won't happen until unblocked by
- * disk_unblock_events().  Events blocking is counted and the actual
- * unblocking happens after the matching number of unblocks are done.
- *
- * Note that this intentionally does not block event checking from
- * disk_clear_events().
- *
- * CONTEXT:
- * Might sleep.
- */
-void disk_block_events(struct gendisk *disk)
-{
-        if (disk->ev)
-                __disk_block_events(disk, true);
-}
-
-/**
  * disk_unblock_events - unblock disk event checking
  * @disk: disk to unblock events for
  *
@@ -1508,10 +1510,18 @@ void disk_unblock_events(struct gendisk *disk)
  */
 void disk_check_events(struct gendisk *disk)
 {
-        if (disk->ev) {
-                __disk_block_events(disk, false);
-                __disk_unblock_events(disk, true);
+        struct disk_events *ev = disk->ev;
+        unsigned long flags;
+
+        if (!ev)
+                return;
+
+        spin_lock_irqsave(&ev->lock, flags);
+        if (!ev->block) {
+                cancel_delayed_work(&ev->dwork);
+                queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
         }
+        spin_unlock_irqrestore(&ev->lock, flags);
 }
 EXPORT_SYMBOL_GPL(disk_check_events);
 
@@ -1546,7 +1556,7 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
         spin_unlock_irq(&ev->lock);
 
         /* uncondtionally schedule event check and wait for it to finish */
-        __disk_block_events(disk, true);
+        disk_block_events(disk);
         queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
         flush_delayed_work(&ev->dwork);
         __disk_unblock_events(disk, false);
@@ -1664,7 +1674,7 @@ static ssize_t disk_events_poll_msecs_store(struct device *dev,
         if (intv < 0 && intv != -1)
                 return -EINVAL;
 
-        __disk_block_events(disk, true);
+        disk_block_events(disk);
         disk->ev->poll_msecs = intv;
         __disk_unblock_events(disk, true);
 
@@ -1750,6 +1760,7 @@ static void disk_add_events(struct gendisk *disk)
         INIT_LIST_HEAD(&ev->node);
         ev->disk = disk;
         spin_lock_init(&ev->lock);
+        mutex_init(&ev->block_mutex);
         ev->block = 1;
         ev->poll_msecs = -1;
         INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
@@ -1770,7 +1781,7 @@ static void disk_del_events(struct gendisk *disk)
         if (!disk->ev)
                 return;
 
-        __disk_block_events(disk, true);
+        disk_block_events(disk);
 
         mutex_lock(&disk_events_mutex);
         list_del_init(&disk->ev->node);