linux-kernel - Re: [PATCH v2] block/laptop_mode: Convert timers to use timer

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Date:   Fri, 6 Oct 2017 08:28:43 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Christoph Hellwig <hch@...radead.org>,
        Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Johannes Weiner <hannes@...xchg.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Jeff Layton <jlayton@...hat.com>, linux-block@...r.kernel.org,
        linux-mm@...ck.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2] block/laptop_mode: Convert timers to use timer_setup()

On 10/06/2017 02:20 AM, Christoph Hellwig wrote:
>> -static void blk_rq_timed_out_timer(unsigned long data)
>> +static void blk_rq_timed_out_timer(struct timer_list *t)
>>  {
>> -	struct request_queue *q = (struct request_queue *)data;
>> +	struct request_queue *q = from_timer(q, t, timeout);
>>  
>>  	kblockd_schedule_work(&q->timeout_work);
>>  }
> 
> This isn't the laptop_mode timer, although the change itself looks fine.
> 
>> +	timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
>> +		    laptop_mode_timer_fn, 0);
> 
> And I already pointed out to Jens when he did the previous changes
> to this one that it has no business being in the block code, it
> really should move to mm/page-writeback.c with the rest of the
> handling of this timer.  Once that is fixed up your automated script
> should pick it up, so we wouldn't need the manual change.

Looks reasonable to me, one comment:

> @@ -916,6 +950,8 @@ EXPORT_SYMBOL(bdi_register_owner);
>   */
>  static void bdi_remove_from_list(struct backing_dev_info *bdi)
>  {
> +	del_timer_sync(&bdi->laptop_mode_wb_timer);
> +
>  	spin_lock_bh(&bdi_lock);
>  	list_del_rcu(&bdi->bdi_list);
>  	spin_unlock_bh(&bdi_lock);

This should go into bdi_unregister() instead.

The rest is mostly mechanical and looks fine to me.

-- 
Jens Axboe