Re: [PATCH] block/cgroup: Drop stale -EBUSY retry from blkg_conf_prep()

[Tang Yizhou <tangyeechou@gmail.com>]

On 22/6/26 4:56 pm, Yang Xiuwei wrote:
> Since commit 8f4236d9008b ("block: remove QUEUE_FLAG_BYPASS and
> ->bypass") nothing in the blkcg blkg lookup/creation path
> returns -EBUSY anymore. blkg_conf_prep() nevertheless still
> retries at fail_exit with msleep(10) and restart_syscall()
> — logic added in 2012 when blk_queue_bypass() could

Hi Xiuwei,

Thanks for the cleanup.

Instead of the vague "logic added in 2012", please mention the commit
e56da7e28796 ("blkcg: don't allow or retain configuration of missing devices").

> cause blkg lookup/creation to fail with -EBUSY while the queue was
> temporarily bypassed during elevator changes.
> 
> Signed-off-by: Yang Xiuwei <yangxiuwei@kylinos.cn>
> ---
>  block/blk-cgroup.c | 10 ----------
>  1 file changed, 10 deletions(-)
> 
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index 3093c1c03902..259f2240e7df 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -919,16 +919,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
>  	spin_unlock_irq(&q->queue_lock);
>  fail_exit:
>  	mutex_unlock(&q->blkcg_mutex);
> -	/*
> -	 * If queue was bypassing, we should retry.  Do so after a
> -	 * short msleep().  It isn't strictly necessary but queue
> -	 * can be bypassing for some time and it's always nice to
> -	 * avoid busy looping.
> -	 */
> -	if (ret == -EBUSY) {
> -		msleep(10);

Since msleep() is gone, we can also remove #include <linux/delay.h>.

With the above addressed, feel free to add:
Reviewed-by: Tang Yizhou <yizhou.tang@shopee.com>

-- 
Best Regards,
Yi

> -		ret = restart_syscall();
> -	}
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(blkg_conf_prep);