linux-kernel - Re: [PATCH] ipc/sem.c: fix update sem_otime when calling sem

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Date:	Wed, 25 Sep 2013 08:55:16 +0200
From:	Manfred Spraul <manfred@...orfullife.com>
To:	Jia He <jiakernel@...il.com>
CC:	Mike Galbraith <bitbucket@...ine.de>, linux-kernel@...r.kernel.org,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] ipc/sem.c: fix update sem_otime when calling sem_op in
 semaphore initialization

Hi Jia,

On 09/25/2013 05:05 AM, Jia He wrote:
>   Hi Manfred
> IIUC after reivewing your patch and src code, does it seem
> sem_otime lost the chance to be updated when calling
> semctl_main/semctl_setval?
> In old codes, even whendo_smart_update(sma, NULL, 0, 0, &tasks),
> the otime can be updated after several conditions checking.
The update is performed now performed inside perform_atomic_semop():

Old code:
perform_atomic_semop() does not update sem_otime. It just returns 0 for 
successfull operations.
This "0 returned" is passed upwards ("semop_completed") into 
do_smart_update()
do_smart_update() updates sem_otime.

New code:
perform_atomic_semop() updates sem_otime immediately (your change).
No need to keep track if a waiting operation was completed (my change).

I don't see a problem - perhaps I overlook something.
Which problem do you see?

--
     Manfred

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