From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757029Ab3DWRg7 (ORCPT ); Tue, 23 Apr 2013 13:36:59 -0400 Received: from g5t0008.atlanta.hp.com ([15.192.0.45]:28072 "EHLO g5t0008.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756861Ab3DWRg6 (ORCPT ); Tue, 23 Apr 2013 13:36:58 -0400 Message-ID: <1366738610.1802.9.camel@buesod1.americas.hpqcorp.net> Subject: Re: [PATCH -mm] ipc,sem: fix locking in semctl_main From: Davidlohr Bueso To: Rik van Riel Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Linus Torvalds , sedat.dilek@gmail.com, Emmanuel Benisty Date: Tue, 23 Apr 2013 10:36:50 -0700 In-Reply-To: <20130423122905.33ac0d3c@annuminas.surriel.com> References: <20130423122905.33ac0d3c@annuminas.surriel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4 (3.4.4-2.fc17) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2013-04-23 at 12:29 -0400, Rik van Riel wrote: > Andrew, here is the patch I promised :) > > Everywhere else in the code, we check sma->sem_perm.deleted under > the semaphore array lock, so we should do teh same here. > The easy fix is to simply not drop and re-take the lock, but keep > it locked. > CCing Linus, Sedat and Emmanuel. This looks very much like a patch I asked Sedat to test during the weekend, which according to him didn't solve his issue. The patch is correct in any case. > This patch can be folded into ipcsem-fine-grained-locking-for-semtimedop.patch > > Signed-off-by: Rik van Riel Acked-by: Davidlohr Bueso > --- > ipc/sem.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/ipc/sem.c b/ipc/sem.c > index 5711616..efdaee6 100644 > --- a/ipc/sem.c > +++ b/ipc/sem.c > @@ -1243,10 +1243,9 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, > err = -EIDRM; > goto out_free; > } > - sem_unlock(sma, -1); > - } > + } else > + sem_lock(sma, NULL, -1); > > - sem_lock(sma, NULL, -1); > for (i = 0; i < sma->sem_nsems; i++) > sem_io[i] = sma->sem_base[i].semval; > sem_unlock(sma, -1);