Re: [PATCH v2] workqueue: Fix double kfree for rescuer

[qzhang2]

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 âdestroy_workqueueâ.
>
> * The function call âdestroy_workqueueâ can be performed there in an if branch
>    after the statement âwq->rescuer = NULLâ was executed.
>
> * This data processing is independent from a possible call of the
>    function âcall_rcu(&wq->rcu, rcu_free_wq)â 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 âkfreeâ can tolerate this special case.
>
>
> Now I find that the proposed change can be inappropriate.
>
> Regards,
> Markus