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From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: torvalds@linux-foundation.org, jannh@google.com,
	paulmck@linux.vnet.ibm.com, bcrl@kvack.org,
	viro@zeniv.linux.org.uk, kent.overstreet@gmail.com,
	security@kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com
Subject: Re: [PATCH 8/8] fs/aio: Use rcu_work instead of explicit rcu and work item
Date: Wed, 21 Mar 2018 10:53:56 -0700	[thread overview]
Message-ID: <20180321175356.GD2149215@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180321171743.GA12834@redhat.com>

Hello,

On Wed, Mar 21, 2018 at 06:17:43PM +0100, Oleg Nesterov wrote:
> Mostly I am asking because I do not really understand
> "[PATCH 6/8] RCU, workqueue: Implement rcu_work".
> 
> I mean, the code looks simple and correct but why does it play with
> WORK_STRUCT_PENDING_BIT? IOW, I do not see a "good" use-case when 2 or more
> queue_rcu_work()'s can use the same rwork and hit work_pending() == T. And
> what the caller should do if queue_rcu_work() returns false?

It's just following standard workqueue conventions.  We can try to
make it more specialized but then flush_rcu_work()'s behavior would
have to different too and it gets confusing quickly.  Unless there are
overriding reasons to deviate, I'd like to keep it consistent.

Thanks.

-- 
tejun

  reply	other threads:[~2018-03-21 17:53 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-14 19:41 [PATCHSET v2] percpu_ref, RCU: Audit RCU usages in percpu_ref users Tejun Heo
2018-03-14 19:45 ` [PATCH 1/8] fs/aio: Add explicit RCU grace period when freeing kioctx Tejun Heo
2018-03-14 19:45   ` [PATCH 2/8] fs/aio: Use RCU accessors for kioctx_table->table[] Tejun Heo
2018-03-14 19:45   ` [PATCH 3/8] RDMAVT: Fix synchronization around percpu_ref Tejun Heo
2018-03-15 22:24     ` Jason Gunthorpe
2018-03-14 19:45   ` [PATCH 4/8] HMM: Remove superflous RCU protection around radix tree lookup Tejun Heo
2018-03-14 19:45     ` Tejun Heo
2018-03-26 14:54     ` Tejun Heo
2018-03-26 14:54       ` Tejun Heo
2018-03-27 16:12       ` Jerome Glisse
2018-03-27 16:12         ` Jerome Glisse
2018-03-14 19:45   ` [PATCH 5/8] percpu_ref: Update doc to dissuade users from depending on internal RCU grace periods Tejun Heo
2018-03-19 17:10     ` Tejun Heo
2018-03-14 19:45   ` [PATCH 6/8] RCU, workqueue: Implement rcu_work Tejun Heo
2018-03-14 20:13     ` Paul E. McKenney
2018-03-16  6:01     ` Lai Jiangshan
2018-03-19 16:45       ` Tejun Heo
2018-03-20 10:04         ` Lai Jiangshan
2018-03-14 19:45   ` [PATCH 7/8] cgroup: Use rcu_work instead of explicit rcu and work item Tejun Heo
2018-03-14 19:45   ` [PATCH 8/8] fs/aio: " Tejun Heo
2018-03-19 17:12     ` Tejun Heo
2018-03-21 15:58     ` Oleg Nesterov
2018-03-21 16:40       ` Tejun Heo
2018-03-21 17:17         ` Oleg Nesterov
2018-03-21 17:53           ` Tejun Heo [this message]
2018-03-22 11:24             ` Oleg Nesterov
2018-03-26 15:04               ` Tejun Heo
2018-03-27 14:28                 ` Oleg Nesterov
2018-03-27 15:55                   ` Tejun Heo
2018-03-29 16:49                     ` Oleg Nesterov
2018-03-29 17:41                       ` Tejun Heo

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