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From: Oleg Nesterov <oleg@tv-sign.ru>
To: Guillaume Chazarain <guichaz@yahoo.fr>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	balbir@linux.vnet.ibm.com, Jonathan Lim <jlim@sgi.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Jay Lan <jlan@cthulhu.engr.sgi.com>
Subject: Re: Add all thread stats for TASKSTATS_CMD_ATTR_TGID (v5)
Date: Tue, 18 Sep 2007 19:29:41 +0400	[thread overview]
Message-ID: <20070918152941.GA177@tv-sign.ru> (raw)
In-Reply-To: <20070918002339.4a989377@localhost.localdomain>

On 09/18, Guillaume Chazarain wrote:
>
> @@ -508,7 +543,7 @@ void taskstats_exit(struct task_struct *
>  	if (!stats)
>  		goto err;
>  
> -	memcpy(stats, tsk->signal->stats, sizeof(*stats));
> +	fill_tgid(tsk->pid, tsk, stats);

No, no, this is wrong.

tsk->signal->stats contains the accumulated info about the already exited
threads, we shouldn't throw it out.

Also, fill_tgid() doesn't make sense here, current is the last live sub-thread.


Hmm. We have another race here. There is no guarantee that tsk->signal->stats
covers all sub-threads, as it is supposed to be. It is quite possible that
another sub-thread decremented ->signal->live before us, but didn't complete
taskstats_exit()->fill_tgid_exit() yet.

Oleg.


  reply	other threads:[~2007-09-18 15:26 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-02 13:53 [PATCH] Add all thread stats for TASKSTATS_CMD_ATTR_TGID Guillaume Chazarain
2007-08-02 19:04 ` Andrew Morton
2007-08-19 19:34   ` Guillaume Chazarain
2007-08-20 17:01     ` Balbir Singh
2007-08-25 15:10       ` Guillaume Chazarain
2007-08-26  4:58         ` Balbir Singh
2007-08-26  9:44           ` Guillaume Chazarain
2007-08-31  3:02           ` Jonathan Lim
2007-08-31  7:24             ` Balbir Singh
2007-08-31 12:35               ` Add all thread stats for TASKSTATS_CMD_ATTR_TGID (v3) Guillaume Chazarain
2007-09-13  0:18                 ` Andrew Morton
2007-09-15 18:42                   ` Add all thread stats for TASKSTATS_CMD_ATTR_TGID (v4) Guillaume Chazarain
2007-09-17 22:23                     ` Add all thread stats for TASKSTATS_CMD_ATTR_TGID (v5) Guillaume Chazarain
2007-09-18 15:29                       ` Oleg Nesterov [this message]
2007-09-20  6:20                       ` Andrew Morton
2007-09-20  8:54                         ` Balbir Singh
2007-09-20 12:16                           ` Oleg Nesterov
2007-09-20 12:17                             ` Balbir Singh
2007-09-07 23:37               ` [PATCH] Add all thread stats for TASKSTATS_CMD_ATTR_TGID Jonathan Lim
2007-09-10 13:03                 ` Guillaume Chazarain
2007-08-15  7:15 ` Balbir Singh

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