From: Ethan Solomita <solo@google.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, pj@sgi.com,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/6] cpuset dirty limits
Date: Tue, 18 Sep 2007 17:23:51 -0700 [thread overview]
Message-ID: <46F06C17.5050203@google.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0709171153010.27542@schroedinger.engr.sgi.com>
Christoph Lameter wrote:
> On Fri, 14 Sep 2007, Andrew Morton wrote:
>
>>> + mutex_lock(&callback_mutex);
>>> + *cs_int = val;
>>> + mutex_unlock(&callback_mutex);
>> I don't think this locking does anything?
>
> Locking is wrong here. The lock needs to be taken before the cs pointer
> is dereferenced from the caller.
I think we can just remove the callback_mutex lock. Since the change is
coming from an update to a cpuset filesystem file, the cpuset is not
going anywhere since the inode is open. And I don't see that any code
really cares whether the dirty ratios change out from under them.
>
>>> + return 0;
>>> +}
>>> +
>>> /*
>>> * Frequency meter - How fast is some event occurring?
>>> *
>>> ...
>>> +void cpuset_get_current_ratios(int *background_ratio, int *throttle_ratio)
>>> +{
>>> + int background = -1;
>>> + int throttle = -1;
>>> + struct task_struct *tsk = current;
>>> +
>>> + task_lock(tsk);
>>> + background = task_cs(tsk)->background_dirty_ratio;
>>> + throttle = task_cs(tsk)->throttle_dirty_ratio;
>>> + task_unlock(tsk);
>> ditto?
>
> It is required to take the task lock while dereferencing the tasks cpuset
> pointer.
Agreed.
-- Ethan
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prev parent reply other threads:[~2007-09-19 0:23 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-17 21:23 [PATCH 0/6] cpuset aware writeback Ethan Solomita
2007-07-17 21:32 ` [PATCH 1/6] cpuset write dirty map Ethan Solomita
2007-07-17 21:33 ` [PATCH 2/6] cpuset write pdflush nodemask Ethan Solomita
2007-07-17 21:34 ` [PATCH 3/6] cpuset write throttle Ethan Solomita
2007-07-17 21:35 ` [PATCH 4/6] cpuset write vmscan Ethan Solomita
2007-07-17 21:36 ` [PATCH 5/6] cpuset write vm writeout Ethan Solomita
2007-07-17 21:37 ` [PATCH 6/6] cpuset dirty limits Ethan Solomita
2007-07-23 20:18 ` [PATCH 0/6] cpuset aware writeback Christoph Lameter
2007-07-23 21:30 ` Ethan Solomita
2007-07-23 21:53 ` Christoph Lameter
2007-09-12 1:32 ` Ethan Solomita
2007-09-12 1:36 ` [PATCH 1/6] cpuset write dirty map Ethan Solomita
2007-09-14 23:15 ` Andrew Morton
2007-09-14 23:47 ` Satyam Sharma
2007-09-15 0:07 ` Andrew Morton
2007-09-15 0:16 ` Satyam Sharma
2007-09-17 18:37 ` Mike Travis
2007-09-17 19:10 ` Christoph Lameter
2007-09-19 0:51 ` Ethan Solomita
2007-09-19 2:14 ` Andrew Morton
2007-09-19 17:08 ` Christoph Lameter
2007-09-19 17:06 ` Christoph Lameter
2007-09-12 1:38 ` [PATCH 2/6] cpuset write pdflush nodemask Ethan Solomita
2007-09-12 1:39 ` [PATCH 3/6] cpuset write throttle Ethan Solomita
[not found] ` <20070914161517.5ea3847f.akpm@linux-foundation.org>
2007-10-03 0:38 ` Ethan Solomita
2007-10-03 17:46 ` Christoph Lameter
2007-10-03 20:46 ` Ethan Solomita
2007-10-04 3:56 ` Christoph Lameter
2007-10-04 7:37 ` Peter Zijlstra
2007-10-04 7:56 ` Paul Jackson
2007-10-04 8:15 ` Peter Zijlstra
2007-10-04 8:25 ` Peter Zijlstra
2007-10-04 9:06 ` Paul Jackson
2007-10-04 9:04 ` Paul Jackson
2007-10-05 19:34 ` Ethan Solomita
2007-09-12 1:40 ` [PATCH 4/6] cpuset write vmscan Ethan Solomita
2007-09-12 1:41 ` [PATCH 5/6] cpuset write vm writeout Ethan Solomita
2007-09-12 1:42 ` [PATCH 6/6] cpuset dirty limits Ethan Solomita
2007-09-14 23:15 ` Andrew Morton
2007-09-17 19:00 ` Christoph Lameter
2007-09-19 0:23 ` Ethan Solomita [this message]
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