@@ -1018,7 +1018,6 @@ static void cached_dev_detach_finish(struct work_struct *w)
BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags));
BUG_ON(refcount_read(&dc->count));
- mutex_lock(&bch_register_lock);
if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
cancel_writeback_rate_update_dwork(dc);
@@ -1034,6 +1033,8 @@ static void cached_dev_detach_finish(struct work_struct *w)
bch_write_bdev_super(dc, &cl);
closure_sync(&cl);
+ mutex_lock(&bch_register_lock);
+
calc_cached_dev_sectors(dc->disk.c);
bcache_device_detach(&dc->disk);
list_move(&dc->list, &uncached_devices);
Now there is variable bcache_is_reboot to prevent device register or unregister during reboot, it is unncessary to still hold mutex lock bch_regsiter_lock before stopping writeback_rate_update kworker and writeback kthread. And if the stopping kworker or kthread holding bch_register_lock inside their routine (we used to have such problem in writeback thread, thanks to Junhui Wang fixed it), it is very easy to introduce deadlock during reboot/shutdown procedure. Therefore in this patch, the location to acquire bch_register_lock is moved to the location before calling calc_cached_dev_sectors(). Which is later then original location in cached_dev_detach_finish(). Signed-off-by: Coly Li <colyli@suse.de> --- drivers/md/bcache/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)