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-rw-r--r--block/genhd.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/block/genhd.c b/block/genhd.c
index ab0731d..3608289 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);