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[SCSI] bsg: fix bsg_mutex hang with device removal

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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>
This commit is contained in:
FUJITA Tomonori 2008-05-29 07:56:55 +09:00 committed by James Bottomley
parent 30e9ba9f20
commit 3f27e3ed11
1 changed files with 6 additions and 3 deletions
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9
block/bsg.c
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@ -724,8 +724,13 @@ static int bsg_put_device(struct bsg_device *bd)
mutex_lock(&bsg_mutex); mutex_lock(&bsg_mutex);
do_free = atomic_dec_and_test(&bd->ref_count); do_free = atomic_dec_and_test(&bd->ref_count);
if (!do_free) if (!do_free) {
mutex_unlock(&bsg_mutex);
goto out; goto out;
}
hlist_del(&bd->dev_list);
mutex_unlock(&bsg_mutex);
dprintk("%s: tearing down\n", bd->name); 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); ret = bsg_complete_all_commands(bd);
hlist_del(&bd->dev_list);
kfree(bd); kfree(bd);
out: out:
mutex_unlock(&bsg_mutex);
kref_put(&q->bsg_dev.ref, bsg_kref_release_function); kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
if (do_free) if (do_free)
blk_put_queue(q); blk_put_queue(q);