Messages in this thread Patch in this message | | | Date | Mon, 4 Aug 2008 14:29:42 -0700 | From | Greg KH <> | Subject | [patch 04/25] SCSI: bsg: fix bsg_mutex hang with device removal |
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2.6.26-stable review patch. If anyone has any objections, please let us know.
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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
commit 3f27e3ed11e67c5ee19d560a50eafd93cf8c6682 upstream
[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> CC: Oliver Pinter <oliver.pntr@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- block/bsg.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/block/bsg.c +++ b/block/bsg.c @@ -725,8 +725,13 @@ static int bsg_put_device(struct bsg_dev 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); @@ -742,10 +747,8 @@ static int bsg_put_device(struct bsg_dev */ 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); --
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