From: Davidlohr Bueso <davidlohr.bueso@hp.com>
Date: Tue, 26 Mar 2013 23:26:03 +0000 (+1100)
Subject: ipc, sem: prevent possible deadlock
X-Git-Tag: next-20130402~2^2~98
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0b33f20865bed709fd231bce1fcf09040e5bf772;p=karo-tx-linux.git

ipc, sem: prevent possible deadlock

In semctl_main(), when cmd == GETALL, we're locking sma->sem_perm.lock
(through sem_lock_and_putref), yet after the conditional, we lock it
again.  Unlock sma right after exiting the conditional.

Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/ipc/sem.c b/ipc/sem.c
index 0dcb73933c25..94b9a0ac60aa 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1115,6 +1115,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 				err = -EIDRM;
 				goto out_free;
 			}
+			sem_unlock(sma, -1);
 		}
 
 		sem_lock(sma, NULL, -1);