1 files changed, 10 insertions, 0 deletions

diff --git a/block/genhd.c b/block/genhd.c
index ab0731d8976d..3608289c8ecd 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 */
@@ -1438,12 +1439,20 @@ void disk_block_events(struct gendisk *disk)
         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)
                 cancel_delayed_work_sync(&disk->ev->dwork);
+
+        mutex_unlock(&ev->block_mutex);
 }
 
 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
@@ -1751,6 +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);