aio: lookup_ioctx can return the wrong value when looking up a bogus context
commit65c24491b4fef017c64e39ec64384fde5e05e0a0
authorJeff Moyer <jmoyer@redhat.com>
Thu, 19 Mar 2009 00:04:21 +0000 (18 17:04 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 19 Mar 2009 22:57:18 +0000 (19 15:57 -0700)
tree3afa5c9eace50837f3c31238102358cf67b8a1ff
parent87c3a86e1c220121d0ced59d1a71e78ed9abc6dd
aio: lookup_ioctx can return the wrong value when looking up a bogus context

The libaio test harness turned up a problem whereby lookup_ioctx on a
bogus io context was returning the 1 valid io context from the list
(harness/cases/3.p).

Because of that, an extra put_iocontext was done, and when the process
exited, it hit a BUG_ON in the put_iocontext macro called from exit_aio
(since we expect a users count of 1 and instead get 0).

The problem was introduced by "aio: make the lookup_ioctx() lockless"
(commit abf137dd7712132ee56d5b3143c2ff61a72a5faa).

Thanks to Zach for pointing out that hlist_for_each_entry_rcu will not
return with a NULL tpos at the end of the loop, even if the entry was
not found.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Zach Brown <zach.brown@oracle.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/aio.c