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SubjectRe: [PATCH] workqueue: Fix double kfree(rescuer) in destroy_workqueue()
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Sorry I didn't describe clearly

I describe the meaning as follows:

destroy_workqueue:
if(wq->rescuer)
struct worker *rescuer = wq->rescuer
kfree(rescuer) //first kfree


if (!(wq->flags & WQ_UNBOUND))
call_rcu(&wq->rcu, rcu_free_wq)

rcu_free_wq
kfree(wq->rescuer) //second kfree

there are double free.

On 5/24/20 11:33 PM, Markus Elfring wrote:
>> When destroy_workqueue if rescuer worker exist,wq->rescuer pointer be
>> kfree. if sanity checks passed. the func call_rcu(&wq->rcu, rcu_free_wq)
>> will be called if the wq->flags & WQ_UNBOUND is false,in rcu_free_wq
>> func wq->rescuer pointer was kfree again.
>
> 1. I suggest to improve also this change description.
> Do you try to explain here that a call of the function “free_workqueue_attrs”
> (or “free_percpu”) would perform sufficient clean-up of system resources
> in this use case?
>
> 2. You proposed to delete the function call “kfree(wq->rescuer)” from
> the implementation of the function “rcu_free_wq”.
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/kernel/workqueue.c?id=c11d28ab4a691736e30b49813fb801847bd44e83#n3482
> https://elixir.bootlin.com/linux/v5.7-rc6/source/kernel/workqueue.c#L3482
>
> This function name should be specified also in the patch subject,
> shouldn't it?
>
> 3. Would you like to add the tag “Fixes” to the commit message?
>
> Regards,
> Markus
>

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