From: Al Viro <viro@ZenIV.linux.org.uk>
Date: Thu, 2 May 2013 23:30:49 +0000 (+0100)
Subject: ipc: fix GETALL/IPC_RM race for sysv semaphores
X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~54
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ce857229e0c3adc211944a13a5579ef84fd7b4af;p=pandora-kernel.git

ipc: fix GETALL/IPC_RM race for sysv semaphores

We can step on WARN_ON_ONCE() in sem_getref() if a semaphore is removed
just as we are about to call sem_getref() from semctl_main(); results
are not pretty.

We should fail with -EIDRM, same as if IPC_RM happened while we'd been
doing allocation there.  This also expands sem_getref() at its only
callsite (and fixed there), while sem_getref_and_unlock() is simply
killed off - it has no callers at all.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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