linux-kernel - Re: [RFC PATCH] blk-mq: fixup RESTART when queue becomes idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <96ec5bc4-fe4c-4ac7-9bec-ee483a1c5b90@kernel.dk>
Date:   Fri, 19 Jan 2018 08:25:43 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Bart Van Assche <Bart.VanAssche@....com>,
        "ming.lei@...hat.com" <ming.lei@...hat.com>
Cc:     "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "hch@...radead.org" <hch@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "osandov@...com" <osandov@...com>,
        "snitzer@...hat.com" <snitzer@...hat.com>
Subject: Re: [RFC PATCH] blk-mq: fixup RESTART when queue becomes idle

On 1/19/18 8:20 AM, Bart Van Assche wrote:
> On Fri, 2018-01-19 at 15:26 +0800, Ming Lei wrote:
>> Please see queue_delayed_work_on(), hctx->run_work is shared by all
>> scheduling, once blk_mq_delay_run_hw_queue(100ms) returns, no new
>> scheduling can make progress during the 100ms.
> 
> How about addressing that as follows:
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index f7515dd95a36..57f8379a476d 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1403,9 +1403,9 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
>  		put_cpu();
>  	}
>  
> -	kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
> -					 &hctx->run_work,
> -					 msecs_to_jiffies(msecs));
> +	kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
> +				    &hctx->run_work,
> +				    msecs_to_jiffies(msecs));
>  }

Exactly. That's why I said it was just a bug in my previous email, not
honoring a newer run is just stupid. Only other thing you have to be
careful with here is the STOPPED bit.

-- 
Jens Axboe