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| Path | csiph.com!goblin2!goblin.stu.neva.ru!aioe.org!bofh.it!news.nic.it!robomod |
|---|---|
| From | Peter Zijlstra <peterz@infradead.org> |
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] ipc/sem.c: Update/correct memory barriers |
| Date | Mon, 10 Aug 2015 10:20:02 +0200 |
| Message-ID | <pVQtk-m5-17@gated-at.bofh.it> (permalink) |
| References | <pVD33-4W3-1@gated-at.bofh.it> |
| X-Original-To | Manfred Spraul <manfred@colorfullife.com> |
| MIME-Version | 1.0 |
| Content-Type | text/plain; charset=us-ascii |
| Content-Disposition | inline |
| User-Agent | Mutt/1.5.21 (2012-12-30) |
| Sender | robomod@news.nic.it |
| List-ID | <linux-kernel.vger.kernel.org> |
| X-Mailing-List | linux-kernel@vger.kernel.org |
| Approved | robomod@news.nic.it |
| Lines | 28 |
| Organization | linux.* mail to news gateway |
| X-Original-Cc | Andrew Morton <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, 1vier1@web.de, Oleg Nesterov <oleg@redhat.com>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Kirill Tkhai <ktkhai@parallels.com>, Ingo Molnar <mingo@redhat.com>, Josh Poimboeuf <jpoimboe@redhat.com>, stable@vger.kernel.org |
| X-Original-Date | Mon, 10 Aug 2015 10:15:52 +0200 |
| X-Original-Message-ID | <20150810081552.GV16853@twins.programming.kicks-ass.net> |
| X-Original-References | <1439142939-2605-1-git-send-email-manfred@colorfullife.com> |
| X-Original-Sender | linux-kernel-owner@vger.kernel.org |
| Xref | csiph.com linux.kernel:1203886 |
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On Sun, Aug 09, 2015 at 07:55:39PM +0200, Manfred Spraul wrote: > sem_lock() did not properly pair memory barriers: > > !spin_is_locked() and spin_unlock_wait() are both only control barriers. > The code needs an acquire barrier, otherwise the cpu might perform > read operations before the lock test. > As no primitive exists inside <include/spinlock.h> and since it seems > noone wants another primitive, the code creates a local primitive within > ipc/sem.c. > > With regards to -stable: > The change of sem_wait_array() is a bugfix, the change to sem_lock() > is a nop (just a preprocessor redefinition to improve the readability). > The bugfix is necessary for all kernels that use sem_wait_array() > (i.e.: starting from 3.10). > > Andrew: Could you include it into your tree and forward it? > > Signed-off-by: Manfred Spraul <manfred@colorfullife.com> > Reported-by: Oleg Nesterov <oleg@redhat.com> > Cc: <stable@vger.kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH] ipc/sem.c: Update/correct memory barriers Manfred Spraul <manfred@colorfullife.com> - 2015-08-09 20:00 +0200 Re: [PATCH] ipc/sem.c: Update/correct memory barriers Peter Zijlstra <peterz@infradead.org> - 2015-08-10 10:20 +0200 Re: [PATCH] ipc/sem.c: Update/correct memory barriers Oleg Nesterov <oleg@redhat.com> - 2015-08-12 15:40 +0200
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