From: qzhang2 <qiang.zhang@windriver.com>
To: Markus Elfring <Markus.Elfring@web.de>, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH v2] workqueue: Fix double kfree for rescuer
Date: Mon, 25 May 2020 18:19:59 +0800 [thread overview]
Message-ID: <bee86d19-6c14-1fd9-eead-24e63af6cf8e@windriver.com> (raw)
In-Reply-To: <7d19381c-2c51-deb4-f82f-d54bc56c6ecf@web.de>
I see, kfree does nothing with null pointers and direct return.
but again kfree is not a good suggestion.
On 5/25/20 5:50 PM, Markus Elfring wrote:
>> The duplicate memory release should be deleted from the implementation
>> of the callback function "rcu_free_wq".
>
> I tried to help with the selection of a better commit message.
> I have taken another look also at the implementation of the function “destroy_workqueue”.
>
> * The function call “destroy_workqueue” can be performed there in an if branch
> after the statement “wq->rescuer = NULL” was executed.
>
> * This data processing is independent from a possible call of the
> function “call_rcu(&wq->rcu, rcu_free_wq)” in another if branch.
> Thus it seems that a null pointer is intentionally passed by a data structure
> member to this callback function on demand.
> The corresponding call of the function “kfree” can tolerate this special case.
>
>
> Now I find that the proposed change can be inappropriate.
>
> Regards,
> Markus
>
next prev parent reply other threads:[~2020-05-25 10:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 7:59 [PATCH] workqueue: Fix double kfree for rescuer qiang.zhang
2020-05-25 8:20 ` [PATCH v2] workqueue: Delete duplicate kfree() call for “rescuer” from rcu_free_wq() Markus Elfring
2020-05-25 9:50 ` [PATCH v2] workqueue: Fix double kfree for rescuer Markus Elfring
2020-05-25 9:55 ` Markus Elfring
2020-05-25 10:19 ` qzhang2 [this message]
2020-05-25 10:40 ` [v2] " Markus Elfring
2020-05-26 2:05 ` qzhang2
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