[ipc] 5769cf63: LTP semget02 TFAILs

From: Fengguang Wu
Date: Fri Jan 17 2014 - 05:24:43 EST

Hi Davidlohr,

We noticed LTP test failures


and the first bad commit is

commit 5769cf6355d87f63906b3e51887eff7017c39217
Author: Davidlohr Bueso <davidlohr@xxxxxx>
AuthorDate: Wed Jan 15 16:56:01 2014 +1100
Commit: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
CommitDate: Wed Jan 15 16:56:01 2014 +1100

ipc: share ids rwsem when possible in ipcget_public

... and rewrite the function. For scenarios where the key is found and
we end up just doing different routinary checks, we can downgrade the
ids->rwsem and share it among concurrent readers. These checks include
the following, which are all safe to share the lock:

ops->more_checks() >> sem_more_checks(), shm_more_checks()
ipc_check_perms() >> ipcperms(),ops->associate() >> [lsm]_[ipctype]_associate()

Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Cc: Aswin Chandramouleeswaran <aswin@xxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

ipc/util.c | 60 +++++++++++++++++++++++++++++++++---------------------------
1 file changed, 33 insertions(+), 27 deletions(-)

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