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| author | Trond Myklebust <trond.myklebust@primarydata.com> | 2014-06-05 11:31:01 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-05 14:52:20 -0700 |
| commit | 0c99fc04f3d4f8a0731c2cc1b2b4d363542b9bbe (patch) | |
| tree | 962ec73c496ee276f5078dc21c835662ba319834 /include/linux | |
| parent | 26935f7537395220e89ccab23b792862e8eacb09 (diff) | |
| download | linux-stable-0c99fc04f3d4f8a0731c2cc1b2b4d363542b9bbe.tar.gz linux-stable-0c99fc04f3d4f8a0731c2cc1b2b4d363542b9bbe.tar.bz2 linux-stable-0c99fc04f3d4f8a0731c2cc1b2b4d363542b9bbe.zip | |
lockdep: Revert lockdep check in raw_seqcount_begin()
commit 22fdcf02f6e80d64a927f702dd9d631a927d87d4 upstream.
This commit reverts the addition of lockdep checking to raw_seqcount_begin
for the following reasons:
1) It violates the naming convention that raw_* functions should not
do lockdep checks (a convention that is also followed by the other
raw_*_seqcount_begin functions).
2) raw_seqcount_begin does not spin, so it can only be part of an ABBA
deadlock in very special circumstances (for instance if a lock
is held across the entire raw_seqcount_begin()+read_seqcount_retry()
loop while also being taken inside the write_seqcount protected area).
3) It is causing false positives with some existing callers, and there
is no non-lockdep alternative for those callers to use.
None of the three existing callers (__d_lookup_rcu, netdev_get_name, and
the NFS state code) appear to use the function in a manner that is ABBA
deadlock prone.
Fixes: 1ca7d67cf5d5: seqcount: Add lockdep functionality to seqcount/seqlock
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/CAHQdGtRR6SvEhXiqWo24hoUh9AU9cL82Z8Z-d8-7u951F_d+5g@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/seqlock.h | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 535f158977b9..8cf350325dc6 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -164,8 +164,6 @@ static inline unsigned read_seqcount_begin(const seqcount_t *s) static inline unsigned raw_seqcount_begin(const seqcount_t *s) { unsigned ret = ACCESS_ONCE(s->sequence); - - seqcount_lockdep_reader_access(s); smp_rmb(); return ret & ~1; } |