This is the wrong way to approach it. Instead of making things ever
more complex try to make it simpler. In this case, ensure that the
destroy_workqueue is not held with pointless locks. Given that the
loop device already is known to not have a reference and marked as in
the rundown state there shouldn't be anything that is required to
be protected by lo_mutex. So something like this untested patch
should probably do the work:
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index fa1c298a8cfb..c734dc768316 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1347,16 +1347,15 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
* became visible.
*/
- mutex_lock(&lo->lo_mutex);
if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) {
err = -ENXIO;
- goto out_unlock;
+ goto out;
}
filp = lo->lo_backing_file;
if (filp == NULL) {
err = -EINVAL;
- goto out_unlock;
+ goto out;
}
if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
@@ -1366,6 +1365,8 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
blk_mq_freeze_queue(lo->lo_queue);
destroy_workqueue(lo->workqueue);
+
+ mutex_lock(&lo->lo_mutex);
spin_lock_irq(&lo->lo_work_lock);
list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
idle_list) {
@@ -1413,8 +1414,8 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
lo_number = lo->lo_number;
disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
-out_unlock:
mutex_unlock(&lo->lo_mutex);
+
if (partscan) {
/*
* open_mutex has been held already in release path, so don't
@@ -1435,7 +1436,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
/* Device is gone, no point in returning error */
err = 0;
}
-
+out:
/*
* lo->lo_state is set to Lo_unbound here after above partscan has
* finished.
