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author | Guo Chao <yan@linux.vnet.ibm.com> | 2013-02-21 15:16:45 -0800 |
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committer | Jens Axboe <axboe@kernel.dk> | 2013-02-22 10:43:21 +0100 |
commit | 5370019dc2d2c2ff90e95d181468071362934f3a (patch) | |
tree | 4e8044b057e43e6b7da9f576cb442cc8df3fabf2 /sound/isa/opti9xx/miro.c | |
parent | d4308febf3551d46884561b7c3fdd62ad3ca7ff2 (diff) | |
download | op-kernel-dev-5370019dc2d2c2ff90e95d181468071362934f3a.zip op-kernel-dev-5370019dc2d2c2ff90e95d181468071362934f3a.tar.gz |
loopdev: fix a deadlock
bd_mutex and lo_ctl_mutex can be held in different order.
Path #1:
blkdev_open
blkdev_get
__blkdev_get (hold bd_mutex)
lo_open (hold lo_ctl_mutex)
Path #2:
blkdev_ioctl
lo_ioctl (hold lo_ctl_mutex)
lo_set_capacity (hold bd_mutex)
Lockdep does not report it, because path #2 actually holds a subclass of
lo_ctl_mutex. This subclass seems creep into the code by mistake. The
patch author actually just mentioned it in the changelog, see commit
f028f3b2 ("loop: fix circular locking in loop_clr_fd()"), also see:
http://marc.info/?l=linux-kernel&m=123806169129727&w=2
Path #2 hold bd_mutex to call bd_set_size(), I've protected it
with i_mutex in a previous patch, so drop bd_mutex at this site.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: M. Hindess <hindessm@uk.ibm.com>
Cc: Nikanth Karthikesan <knikanth@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'sound/isa/opti9xx/miro.c')
0 files changed, 0 insertions, 0 deletions