From: "hch@lst.de" <hch@lst.de>
To: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: "hch@lst.de" <hch@lst.de>, "hare@suse.com" <hare@suse.com>,
"jthumshirn@suse.de" <jthumshirn@suse.de>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"oleksandr@natalenko.name" <oleksandr@natalenko.name>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"ming.lei@redhat.com" <ming.lei@redhat.com>
Subject: Re: [PATCH v4 4/7] block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag
Date: Mon, 2 Oct 2017 18:14:33 +0200 [thread overview]
Message-ID: <20171002161433.GA11022@lst.de> (raw)
In-Reply-To: <1506959767.3368.18.camel@wdc.com>
On Mon, Oct 02, 2017 at 03:56:08PM +0000, Bart Van Assche wrote:
> Since queue_flag_set() and queue_flag_clear() use non-atomic primitives to
> set and clear flags it is essential to protect calls of these functions with
> the queue lock. Otherwise flag updates could get lost due to concurrent
> queue_flag_set() or queue_flag_clear() calls.
>
> One of the reasons why I introduced this helper function is to keep the
> wake_up_all(&q->mq_freeze_wq) call that is added to this function by a later
> patch in the block layer.
Oh, despite the _unlocked versions existing it doesn't do any atomic
ops. Yeah, we'll need the queue lock then.
But please split it into one helper for setting the queue blocked
and to clear it, especially if the clear needs to do an additional
wake_up.
next prev parent reply other threads:[~2017-10-02 16:14 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 20:29 [PATCH v4 0/7] Make suspend and resume safe for md-on-SCSI Bart Van Assche
2017-09-25 20:29 ` [PATCH v4 1/7] md: Make md resync and reshape threads freezable Bart Van Assche
2017-09-25 23:04 ` Ming Lei
2017-09-25 23:09 ` Bart Van Assche
2017-09-25 23:09 ` Bart Van Assche
2017-09-26 4:01 ` Ming Lei
2017-09-26 8:13 ` Ming Lei
2017-09-26 14:40 ` Bart Van Assche
2017-09-26 14:40 ` Bart Van Assche
2017-09-26 15:02 ` Ming Lei
2017-09-26 6:06 ` Hannes Reinecke
2017-09-26 11:17 ` Ming Lei
2017-09-26 14:42 ` Bart Van Assche
2017-09-26 14:42 ` Bart Van Assche
2017-09-26 14:59 ` Ming Lei
2017-09-27 3:12 ` Bart Van Assche
2017-09-27 3:12 ` Bart Van Assche
2017-09-27 11:00 ` Ming Lei
2017-10-02 15:39 ` Bart Van Assche
2017-10-02 15:39 ` Bart Van Assche
2017-10-02 13:26 ` Christoph Hellwig
2017-09-25 20:29 ` [PATCH v4 2/7] block: Make q_usage_counter also track legacy requests Bart Van Assche
2017-09-26 6:05 ` Hannes Reinecke
2017-09-26 8:34 ` Ming Lei
2017-10-02 13:29 ` Christoph Hellwig
2017-09-25 20:29 ` [PATCH v4 3/7] block: Convert RQF_PREEMPT into REQ_PREEMPT Bart Van Assche
2017-10-02 13:42 ` Christoph Hellwig
2017-10-02 13:43 ` Christoph Hellwig
2017-09-25 20:29 ` [PATCH v4 4/7] block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag Bart Van Assche
2017-10-02 13:47 ` Christoph Hellwig
2017-10-02 15:56 ` Bart Van Assche
2017-10-02 16:14 ` hch [this message]
2017-09-25 20:29 ` [PATCH v4 5/7] scsi: Reduce suspend latency Bart Van Assche
2017-09-26 22:23 ` Ming Lei
2017-09-27 3:43 ` Bart Van Assche
2017-09-27 5:37 ` Ming Lei
2017-09-25 20:29 ` [PATCH v4 6/7] scsi: Set QUEUE_FLAG_PREEMPT_ONLY while quiesced Bart Van Assche
2017-10-02 13:53 ` Christoph Hellwig
2017-09-25 20:29 ` [PATCH v4 7/7] block: Make SCSI device suspend and resume work reliably Bart Van Assche
2017-09-25 22:59 ` Ming Lei
2017-09-25 23:13 ` Bart Van Assche
2017-09-26 8:32 ` Ming Lei
2017-09-26 14:44 ` Bart Van Assche
2017-09-26 9:15 ` [PATCH v4 0/7] Make suspend and resume safe for md-on-SCSI Ming Lei
2017-09-26 14:29 ` Bart Van Assche
2017-09-26 14:54 ` Ming Lei
2017-09-26 20:17 ` Bart Van Assche
2017-09-26 22:47 ` Ming Lei
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