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author | 2009-04-06 17:41:00 +0200 | |
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committer | 2009-04-07 08:34:46 -0700 | |
commit | 7bfac9ecf0585962fe13584f5cf526d8c8e76f17 (patch) | |
tree | 7e7c98311bb0d4c26e514b337216bbc8ade8d078 /include/net | |
parent | nilfs2: support nanosecond timestamp (diff) | |
download | linux-7bfac9ecf0585962fe13584f5cf526d8c8e76f17.tar.gz linux-7bfac9ecf0585962fe13584f5cf526d8c8e76f17.tar.bz2 linux-7bfac9ecf0585962fe13584f5cf526d8c8e76f17.zip |
splice: fix deadlock in splicing to file
There's a possible deadlock in generic_file_splice_write(),
splice_from_pipe() and ocfs2_file_splice_write():
- task A calls generic_file_splice_write()
- this calls inode_double_lock(), which locks i_mutex on both
pipe->inode and target inode
- ordering depends on inode pointers, can happen that pipe->inode is
locked first
- __splice_from_pipe() needs more data, calls pipe_wait()
- this releases lock on pipe->inode, goes to interruptible sleep
- task B calls generic_file_splice_write(), similarly to the first
- this locks pipe->inode, then tries to lock inode, but that is
already held by task A
- task A is interrupted, it tries to lock pipe->inode, but fails, as
it is already held by task B
- ABBA deadlock
Fix this by explicitly ordering locks: the outer lock must be on
target inode and the inner lock (which is later unlocked and relocked)
must be on pipe->inode. This is OK, pipe inodes and target inodes
form two nonoverlapping sets, generic_file_splice_write() and friends
are not called with a target which is a pipe.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/net')
0 files changed, 0 insertions, 0 deletions