From: Rik van Riel <riel@surriel.com>
To: Michel Lespinasse <walken@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Sasha Levin <sasha.levin@oracle.com>,
torvalds@linux-foundation.org, davidlohr.bueso@hp.com,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
hhuang@redhat.com, jason.low2@hp.com, lwoodman@redhat.com,
chegu_vinod@hp.com, Dave Jones <davej@redhat.com>,
benisty.e@gmail.com, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v2 -mm -next] ipc,sem: fix lockdep false positive
Date: Fri, 29 Mar 2013 09:24:58 -0400 [thread overview]
Message-ID: <5155962A.9070705@surriel.com> (raw)
In-Reply-To: <CANN689FGoTF=5sbYSE7JyyS9CyyYTLrjHq5B0O23tFuCh550qg@mail.gmail.com>
On 03/29/2013 09:08 AM, Michel Lespinasse wrote:
>> That is where I had it initially. I may have gotten too clever
>> and worked on keeping more accesses read-only. If you want, I
>> can move it back here and re-submit the patch :)
>
> I think I would prefer that - I feel having it upper serves little
> purpose, as you still need to check it here, so we might as well be
> optimistic and check it only here. Or maybe I've missed the benefit of
> having it earlier - I just don't see it.
OK, will do.
> It still makes it possible (though less likely) that each simple semop
> taking this path might make the next one take it too, though. So, I'm
> not sure how to balance that against the starvation possibility. I'll
> leave it up to you then :)
Lets optimistically assume that userland is using the semaphores
for synchronization. That rather limits the potential for starvation.
--
All rights reversed.
next prev parent reply other threads:[~2013-03-29 13:25 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-20 19:55 ipc,sem: sysv semaphore scalability Rik van Riel
2013-03-20 19:55 ` [PATCH 1/7] ipc: remove bogus lock comment for ipc_checkid Rik van Riel
2013-03-20 19:55 ` [PATCH 2/7] ipc: introduce obtaining a lockless ipc object Rik van Riel
2013-03-20 19:55 ` [PATCH 3/7] ipc: introduce lockless pre_down ipcctl Rik van Riel
2013-03-20 19:55 ` [PATCH 4/7] ipc,sem: do not hold ipc lock more than necessary Rik van Riel
2013-03-20 19:55 ` [PATCH 5/7] ipc,sem: open code and rename sem_lock Rik van Riel
2013-03-22 1:14 ` Davidlohr Bueso
2013-03-20 19:55 ` [PATCH 6/7] ipc,sem: have only one list in struct sem_queue Rik van Riel
2013-03-22 1:14 ` Davidlohr Bueso
2013-03-20 19:55 ` [PATCH 7/7] ipc,sem: fine grained locking for semtimedop Rik van Riel
2013-03-22 1:14 ` Davidlohr Bueso
2013-03-22 23:01 ` Michel Lespinasse
2013-03-22 23:38 ` Rik van Riel
2013-03-22 23:42 ` [PATCH 7/7 part3] fix for sem_lock Rik van Riel
2013-03-20 20:49 ` ipc,sem: sysv semaphore scalability Linus Torvalds
2013-03-20 20:56 ` Linus Torvalds
2013-03-20 20:57 ` Davidlohr Bueso
2013-03-21 21:10 ` Andrew Morton
2013-03-21 21:47 ` Peter Hurley
2013-03-21 21:50 ` Peter Hurley
2013-03-21 22:01 ` Andrew Morton
2013-03-22 3:38 ` Rik van Riel
2013-03-26 19:28 ` Dave Jones
2013-03-26 19:43 ` Andrew Morton
2013-03-29 16:17 ` Dave Jones
2013-03-29 18:00 ` Linus Torvalds
2013-03-29 18:04 ` Dave Jones
2013-03-29 18:10 ` Linus Torvalds
2013-03-29 18:43 ` Linus Torvalds
2013-03-29 19:06 ` Dave Jones
2013-03-29 19:13 ` Linus Torvalds
2013-03-29 19:26 ` Linus Torvalds
2013-03-29 19:36 ` Peter Hurley
2013-04-02 16:08 ` Sasha Levin
2013-04-02 17:24 ` Linus Torvalds
2013-04-02 17:52 ` Linus Torvalds
2013-04-02 19:53 ` Sasha Levin
2013-04-02 20:00 ` Dave Jones
2013-03-29 19:33 ` Peter Hurley
2013-03-29 19:54 ` Linus Torvalds
2013-04-01 7:40 ` Stanislav Kinsbursky
2013-03-29 20:41 ` Linus Torvalds
2013-03-29 21:12 ` Linus Torvalds
2013-03-29 23:16 ` Linus Torvalds
2013-03-30 1:36 ` Emmanuel Benisty
2013-03-30 2:08 ` Davidlohr Bueso
2013-03-30 3:02 ` Emmanuel Benisty
2013-03-30 3:46 ` Linus Torvalds
2013-03-30 4:33 ` Emmanuel Benisty
2013-03-30 5:10 ` Linus Torvalds
2013-03-30 5:57 ` Emmanuel Benisty
2013-03-30 17:22 ` Linus Torvalds
2013-03-31 2:38 ` Emmanuel Benisty
2013-03-31 5:01 ` Davidlohr Bueso
2013-03-31 13:45 ` Rik van Riel
2013-03-31 17:10 ` Linus Torvalds
2013-03-31 17:02 ` Emmanuel Benisty
2013-03-30 2:09 ` Linus Torvalds
2013-03-30 2:55 ` Davidlohr Bueso
2013-03-29 19:01 ` Dave Jones
2013-05-03 15:03 ` Peter Hurley
2013-03-22 1:12 ` Davidlohr Bueso
2013-03-22 1:23 ` Linus Torvalds
2013-03-22 3:40 ` Rik van Riel
2013-03-22 7:30 ` Mike Galbraith
2013-03-22 11:04 ` Emmanuel Benisty
2013-03-22 15:37 ` Linus Torvalds
2013-03-23 3:19 ` Emmanuel Benisty
2013-03-23 19:45 ` Linus Torvalds
2013-03-24 13:46 ` Emmanuel Benisty
2013-03-24 17:10 ` Linus Torvalds
2013-03-25 13:47 ` Emmanuel Benisty
2013-03-25 14:00 ` Rik van Riel
2013-03-25 14:03 ` Rik van Riel
2013-03-25 15:20 ` Emmanuel Benisty
2013-03-25 15:53 ` Rik van Riel
2013-03-25 17:09 ` Emmanuel Benisty
2013-03-25 14:01 ` Rik van Riel
2013-03-25 14:21 ` Emmanuel Benisty
2013-03-26 17:59 ` Davidlohr Bueso
2013-03-26 18:14 ` Rik van Riel
2013-03-26 18:35 ` Andrew Morton
2013-04-16 23:30 ` Andrew Morton
2013-05-04 15:55 ` Jörn Engel
2013-05-04 18:12 ` Borislav Petkov
2013-05-06 14:47 ` Jörn Engel
2013-03-22 17:51 ` Davidlohr Bueso
2013-03-25 20:21 ` Sasha Levin
2013-03-25 20:38 ` [PATCH -mm -next] ipc,sem: fix lockdep false positive Rik van Riel
2013-03-25 21:42 ` Michel Lespinasse
2013-03-25 21:51 ` Michel Lespinasse
2013-03-25 21:56 ` Sasha Levin
2013-03-25 21:52 ` Sasha Levin
2013-03-26 13:19 ` Peter Zijlstra
2013-03-26 13:40 ` Michel Lespinasse
2013-03-26 14:27 ` Peter Zijlstra
2013-03-26 15:19 ` Rik van Riel
2013-03-27 8:40 ` Peter Zijlstra
2013-03-27 8:42 ` Peter Zijlstra
2013-03-27 11:22 ` Michel Lespinasse
2013-03-27 12:02 ` Peter Zijlstra
2013-03-27 20:00 ` Rik van Riel
2013-03-28 20:23 ` [PATCH v2 " Rik van Riel
2013-03-29 2:50 ` Michel Lespinasse
2013-03-29 9:57 ` Peter Zijlstra
2013-03-29 13:21 ` Michel Lespinasse
2013-03-29 12:07 ` Rik van Riel
2013-03-29 13:08 ` Michel Lespinasse
2013-03-29 13:24 ` Rik van Riel [this message]
2013-03-29 13:55 ` [PATCH v3 " Rik van Riel
2013-03-29 13:59 ` Michel Lespinasse
2013-03-26 14:25 ` [PATCH " Rik van Riel
2013-03-26 17:33 ` ipc,sem: sysv semaphore scalability Sasha Levin
2013-03-26 17:51 ` Davidlohr Bueso
2013-03-26 18:07 ` Sasha Levin
2013-03-26 18:17 ` Rik van Riel
2013-03-26 20:00 ` [PATCH -mm -next] ipc,sem: untangle RCU locking with find_alloc_undo Rik van Riel
2013-04-05 4:38 ` Mike Galbraith
2013-04-05 13:21 ` Rik van Riel
2013-04-05 16:26 ` Mike Galbraith
2013-04-16 12:37 ` Mike Galbraith
2013-03-26 17:55 ` ipc,sem: sysv semaphore scalability Paul E. McKenney
2013-03-28 15:32 ` [PATCH -mm -next] ipc,sem: untangle RCU locking with find_alloc_undo Rik van Riel
2013-03-28 21:05 ` Davidlohr Bueso
2013-03-29 1:00 ` Michel Lespinasse
2013-03-29 1:14 ` Sasha Levin
2013-03-30 13:35 ` Sasha Levin
2013-03-31 1:30 ` Rik van Riel
2013-03-31 4:09 ` Davidlohr Bueso
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