Messages in this thread | | | Subject | Re: [PATCH v3] workqueue: Fix double kfree for rescuer | From | Markus Elfring <> | Date | Mon, 25 May 2020 12:01:59 +0200 |
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> The callback function "rcu_free_wq" could be called after memory > was released for "rescuer" already, Thus delete a misplaced call > of the function "kfree".
I got into the mood to follow your interpretation of the software situation for a moment.
I have taken another look also at the implementation of the function “destroy_workqueue”.
* The function call “kfree(rescuer)” 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. I'm sorry for undesirable confusion because of this patch review.
Regards, Markus
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