[SCSI] bsg: fix bsg_mutex hang with device removal
We don't need to hold bsg_mutex during bsg_complete_all_commands(). It
leads to a problem that we block bsg_unregister_queue during
bsg_complete_all_commands (untill all the outstanding commands
complete).
Thanks to Pete Wyckoff for finding the bug and testing the patch.
The detailed bug report is:
http://marc.info/?l=linux-scsi&m=121182137132145&w=2
Tested-by: Pete Wyckoff <pw@osc.edu>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/block/bsg.c b/block/bsg.c
index f0b7cd3..7cdec32 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -724,8 +724,13 @@
mutex_lock(&bsg_mutex);
do_free = atomic_dec_and_test(&bd->ref_count);
- if (!do_free)
+ if (!do_free) {
+ mutex_unlock(&bsg_mutex);
goto out;
+ }
+
+ hlist_del(&bd->dev_list);
+ mutex_unlock(&bsg_mutex);
dprintk("%s: tearing down\n", bd->name);
@@ -741,10 +746,8 @@
*/
ret = bsg_complete_all_commands(bd);
- hlist_del(&bd->dev_list);
kfree(bd);
out:
- mutex_unlock(&bsg_mutex);
kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
if (do_free)
blk_put_queue(q);