From: Tejun Heo <tj@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: jack@suse.cz, axboe@kernel.dk, clm@fb.com, jbacik@fb.com,
kernel-team@fb.com, linux-kernel@vger.kernel.org,
linux-btrfs@vger.kernel.org, peterz@infradead.org,
jianchao.w.wang@oracle.com, Bart.VanAssche@wdc.com
Subject: Re: [PATCH 1/7] blk-mq: protect completion path with RCU
Date: Mon, 8 Jan 2018 09:12:34 -0800 [thread overview]
Message-ID: <20180108171234.GX3668920@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20171229100418.GB4020@infradead.org>
Hello, Christoph.
On Fri, Dec 29, 2017 at 02:04:18AM -0800, Christoph Hellwig wrote:
> Why do you need the srcu protection? The completion path can never
> sleep.
>
> If there is a good reason to keep it please add commment, and
> make the srcu variant a separate function only used by drivers that
> need it instead of adding the conditional.
It's either that or adding protection against both srcu and rcu in the
counterpart. It's easier / cleaner to just use single rcu construct
for a given queue. Will add a comment. Jens already has a patch
which factors out the conditionals.
Thanks.
--
tejun
next prev parent reply other threads:[~2018-01-08 17:12 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-16 12:07 [PATCHSET v3] blk-mq: reimplement timeout handling Tejun Heo
2017-12-16 12:07 ` [PATCH 1/7] blk-mq: protect completion path with RCU Tejun Heo
2017-12-29 10:04 ` Christoph Hellwig
2018-01-08 17:12 ` Tejun Heo [this message]
2017-12-16 12:07 ` [PATCH 2/7] blk-mq: replace timeout synchronization with a RCU and generation based scheme Tejun Heo
2017-12-16 12:07 ` [PATCH 3/7] blk-mq: use blk_mq_rq_state() instead of testing REQ_ATOM_COMPLETE Tejun Heo
2017-12-16 12:07 ` [PATCH 4/7] blk-mq: make blk_abort_request() trigger timeout path Tejun Heo
2017-12-29 10:07 ` Christoph Hellwig
2017-12-16 12:07 ` [PATCH 5/7] blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mq Tejun Heo
2017-12-21 3:56 ` jianchao.wang
2017-12-21 13:50 ` Tejun Heo
2017-12-22 4:02 ` jianchao.wang
2018-01-08 17:27 ` Tejun Heo
2018-01-09 3:08 ` jianchao.wang
2018-01-09 3:37 ` Tejun Heo
2018-01-09 5:59 ` jianchao.wang
2017-12-16 12:07 ` [PATCH 6/7] blk-mq: remove REQ_ATOM_STARTED Tejun Heo
2017-12-16 12:07 ` [PATCH 7/7] blk-mq: rename blk_mq_hw_ctx->queue_rq_srcu to ->srcu Tejun Heo
2017-12-29 10:02 ` [PATCHSET v3] blk-mq: reimplement timeout handling Christoph Hellwig
2018-01-08 17:03 ` Tejun Heo
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