[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 <[email protected]> Signed-off-by: FUJITA Tomonori <[email protected]> Signed-off-by: James Bottomley <[email protected]>
kishon · Jul 12, 2008 · 3f27e3e · 3f27e3e
1 parent 30e9ba9
commit 3f27e3e
Showing 1 changed file with 6 additions and 3 deletions.
diff --git a/block/bsg.c b/block/bsg.c
@@ -724,8 +724,13 @@ static int bsg_put_device(struct bsg_device *bd)
 	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 @@ static int bsg_put_device(struct bsg_device *bd)
 	 */
 	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);