linux-kernel - Re: [PATCH 2/2] bdi: Avoid oops on device removal

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Date:	Thu, 27 Feb 2014 15:07:48 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Jens Axboe <axboe@...nel.dk>, stable@...r.kernel.org
Subject: Re: [PATCH 2/2] bdi: Avoid oops on device removal

Hello,

On Tue, Feb 25, 2014 at 11:29:14PM +0100, Jan Kara wrote:
> +static void bdi_wakeup_thread(struct backing_dev_info *bdi)
> +{
> +	spin_lock_bh(&bdi->wb_lock);
> +	if (test_bit(BDI_registered, &bdi->state))
> +		mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
> +	spin_unlock_bh(&bdi->wb_lock);
> +}

I wonder whether this can be smarter without requiring wb_lock each
timer but this probably is the simplest for -stable backports.

>  static void bdi_queue_work(struct backing_dev_info *bdi,
>  			   struct wb_writeback_work *work)
>  {
>  	trace_writeback_queue(bdi, work);
>  
>  	spin_lock_bh(&bdi->wb_lock);
> +	if (!test_bit(BDI_registered, &bdi->state)) {
> +		if (work->done)
> +			complete(work->done);
> +		goto out_unlock;
> +	}
>  	list_add_tail(&work->list, &bdi->work_list);
> -	spin_unlock_bh(&bdi->wb_lock);
> -
>  	mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
> +out_unlock:
> +	spin_unlock_bh(&bdi->wb_lock);
>  }
>  
> +
> +

Why three blank lines?

Other than that,

Reviewed-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun
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