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From: Markus Elfring <Markus.Elfring@web.de>
To: Zhang Qiang <qiang.zhang@windriver.com>,
	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 11:50:20 +0200	[thread overview]
Message-ID: <7d19381c-2c51-deb4-f82f-d54bc56c6ecf@web.de> (raw)
In-Reply-To: <20200525075901.12699-1-qiang.zhang@windriver.com>

> 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

  parent reply	other threads:[~2020-05-25  9:50 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-25  7:59 [PATCH] " 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 ` Markus Elfring [this message]
2020-05-25  9:55   ` [PATCH v2] workqueue: Fix double kfree for rescuer Markus Elfring
2020-05-25 10:19   ` qzhang2
2020-05-25 10:40     ` [v2] " Markus Elfring
2020-05-26  2:05       ` qzhang2

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