From: Manfred Spraul <manfred@colorfullife.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
1vier1@web.de
Subject: Re: [PATCH 6/6] ipc/sem.c: make semctl(,,{GETNCNT,GETZCNT}) standard compliant
Date: Tue, 20 May 2014 20:30:05 +0200 [thread overview]
Message-ID: <537B9F2D.6060606@colorfullife.com> (raw)
In-Reply-To: <20140519154639.5570a30f8b47872a323dcdfd@linux-foundation.org>
Hi Andrew,
On 05/20/2014 12:46 AM, Andrew Morton wrote:
> On Sun, 18 May 2014 09:58:37 +0200 Manfred Spraul <manfred@colorfullife.com> wrote:
>
>> SUSv4 clearly defines how semncnt and semzcnt must be calculated:
>> A task waits on exactly one semaphore:
>> The semaphore from the first operation in the sop array that cannot proceed.
>>
>> The Linux implementation never followed the standard, it tried to count all
>> semaphores that might be the reason why a task sleeps.
>>
>> This patch fixes that.
> What are the back-compatibility implications of this change?
A really good question:
- there is no application in Fedora that uses GETNCNT or GETZCNT.
- application that use only single-sop semop() are also safe, the
difference only affects complex apps.
- portable application are also safe, the new behavior is standard
compliant.
But that's it. The old behavior existed in Linux from 0.99.something
until now.
What about adding a WARN_ON_ONCE() if the case where the behavior
differs happens?
Should I write a patch?
--
Manfred
next prev parent reply other threads:[~2014-05-20 18:30 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-18 7:58 [PATCH 0/6] ipc/sem.c: Fix semctl(,,{GETNCNT,GETZCNT}) Manfred Spraul
2014-05-18 7:58 ` [PATCH 1/6] ipc/sem.c: further whitespace cleanups Manfred Spraul
2014-05-18 7:58 ` [PATCH 2/6] ipc/sem.c: Bugfix for semctl(,,GETZCNT) Manfred Spraul
2014-05-18 7:58 ` [PATCH 3/6] ipc/sem.c: remove code duplication Manfred Spraul
2014-05-18 7:58 ` [PATCH 4/6] ipc/sem.c: Change perform_atomic_semop parameters Manfred Spraul
2014-05-18 7:58 ` [PATCH 5/6] ipc/sem.c: Store which operation blocks in perform_atomic_semop() Manfred Spraul
2014-05-18 7:58 ` [PATCH 6/6] ipc/sem.c: make semctl(,,{GETNCNT,GETZCNT}) standard compliant Manfred Spraul
2014-05-19 22:46 ` Andrew Morton
2014-05-20 6:56 ` Michael Kerrisk (man-pages)
2014-05-20 18:30 ` Manfred Spraul [this message]
2014-05-20 19:01 ` Andrew Morton
2014-05-18 18:03 ` [PATCH 0/6] ipc/sem.c: Fix semctl(,,{GETNCNT,GETZCNT}) Davidlohr Bueso
-- strict thread matches above, loose matches on Subject: below --
2014-05-10 10:03 Manfred Spraul
2014-05-10 10:03 ` [PATCH 1/6] ipc/sem.c: further whitespace cleanups Manfred Spraul
2014-05-10 10:03 ` [PATCH 2/6] ipc/sem.c: Bugfix for semctl(,,GETZCNT) Manfred Spraul
2014-05-10 10:03 ` [PATCH 3/6] ipc/sem.c: remove code duplication Manfred Spraul
2014-05-10 10:03 ` [PATCH 4/6] ipc/sem.c: Change perform_atomic_semop parameters Manfred Spraul
2014-05-10 10:03 ` [PATCH 5/6] ipc/sem.c: Store which operation blocks in perform_atomic_semop() Manfred Spraul
2014-05-10 10:03 ` [PATCH 6/6] ipc/sem.c: make semctl(,,{GETNCNT,GETZCNT}) standard compliant Manfred Spraul
2014-05-14 14:52 ` Davidlohr Bueso
2014-05-14 22:30 ` Andrew Morton
2014-05-15 4:24 ` Manfred Spraul
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