Merge branch 'stable/bug.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git...

[pandora-kernel.git] / block / genhd.c

diff --git a/block/genhd.c b/block/genhd.c
index ab0731d..3608289 100644 (file)
--- 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);