Sorry, Pter Mladek, this is my mistake please ignore this change.
________________________________________
发件人: linux-kernel-ow...@vger.kernel.org <linux-kernel-ow...@vger.kernel.org> 代表
Petr Mladek <pmla...@suse.com>
发送时间: 2020年7月7日 17:06
收件人: Zhang, Qiang
抄送: ben.do...@codethink.co.uk; bfie...@redhat.com; c...@rock-chips.com;
pet...@infradead.org; t...@kernel.org; a...@linux-foundation.org;
naresh.kamb...@linaro.org; mm-comm...@vger.kernel.org;
linux-kernel@vger.kernel.org
主题: Re: [PATCH v4] kthread: Work could not be queued when worker being destroyed
On Mon 2020-07-06 13:46:47, qiang.zh...@windriver.com wrote:
> From: Zhang Qiang <qiang.zh...@windriver.com>
>
> Before the work is put into the queue of the worker thread,
> the state of the worker thread needs to be detected,because
> the worker thread may be in the destruction state at this time.
>
> Signed-off-by: Zhang Qiang <qiang.zh...@windriver.com>
> Suggested-by: Petr Mladek <pmla...@suse.com>
> Reviewed-by: Petr Mladek <pmla...@suse.com>
This patch is completely different from the one that I suggested
or acked. Please, never keep acks when doing major rework and
people did not agree with it.
For this patch:
Nacked-by: Petr Mladek <pmla...@suse.com>
See below why.
> ---
> v1->v2:
> Add warning information for condition "!worker->task".
> v2->v3:
> Modify submission information and add "Reviewed-by" tags.
> v3->v4:
> Fix spi controller register trigger Warning.
> when a spi controller register, a "kthread_worker_fn" worker is created
> through "kthread_run" instead of "kthread_create_worker" which in this
> func the "worker->task" will be initialized. and then the "spi_start_queue"
> func queue a work to worker queue, at this time, if the worker has not
> begin to running, the "!worker->task" will be true, so a warning is
> triggered.
>
> kernel/kthread.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index bfbfa481be3a..825bd4dcdb95 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -791,6 +791,11 @@ static inline bool queuing_blocked(struct kthread_worker
> *worker,
> {
> lockdep_assert_held(&worker->lock);
>
> + if (kthread_should_stop()) {
This does not make much sense.
kthread_should_stop() checks a flag set for the "current" process.
It works only when called from inside the kthread worker thread.
queuing_blocked() is called from kthread_queue_work()
or kthread_queue_delayed_work(). These are typically
called from another process. The only exception is when
they get re-queued from inside the work.
Best Regards,
Petr
> + WARN_ON(1);
> + return true;
> + }
> +
> return !list_empty(&work->node) || work->canceling;
> }
>
> --
> 2.24.1
