From: Tejun Heo <tj@kernel.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Josef Bacik <josef@toxicpanda.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH workqueue/for-4.14-fixes] workqueue: replace pool->manager_arb mutex with a flag
Date: Mon, 9 Oct 2017 08:08:08 -0700 [thread overview]
Message-ID: <20171009150808.GD3301751@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <CAJhGHyAQuArNBTWcAr5Dq_Lj58yMYUs_01ObNGTJrCt=3Ni3rg@mail.gmail.com>
Hello,
On Mon, Oct 09, 2017 at 11:02:34PM +0800, Lai Jiangshan wrote:
> I was also thinking alternative code when reviewing.
> The first is quite obvious. Testing POOL_MANAGER_ACTIVE
> can be replaced by testing pool->manager.
> And POOL_MANAGER_ACTIVE is not needed. Isn't it?
put_unbound_pool() doesn't have to be called from a kworker context
and we don't really have a kworker pointer to set pool->manager to.
We can use a bogus value and then update pool->manager dereferences
accordingly but I think it's cleaner to simply use a separate flag.
> The second thing is to make manage_workers()
> and put_unbound_pool() exclusive.
> Waiting event on POOL_MANAGER_ACTIVE(or pool->manager)
> is one way. However, the pool's refcnt is not possible to
> be dropped to zero now since the caller still hold the pool->lock
wait_event_lock_irq() drops the lock if the condition is not met
before going to sleep (otherwise it wouldn't be able to sleep).
> and some pwds of the works in the worklist. So the other way
> to enforce the exclusive could be just doing
> get_pwq(the first pwd of the worklist) and put_pwq() when
> the manage_workers() done. And the code about
> pool->manager_arb in put_unbound_pool() can be
> simply removed.
Yeah, that part is removed.
Thanks!
--
tejun
next prev parent reply other threads:[~2017-10-09 15:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-08 9:02 [RFC] workqueue: Fix irq inversion deadlock in manage_workers() Boqun Feng
2017-10-08 19:03 ` Tejun Heo
2017-10-09 3:24 ` Boqun Feng
2017-10-09 6:42 ` Peter Zijlstra
2017-10-09 13:07 ` Tejun Heo
2017-10-09 9:40 ` Lai Jiangshan
2017-10-09 12:40 ` Boqun Feng
2017-10-09 15:24 ` Peter Zijlstra
2017-10-09 15:29 ` Tejun Heo
2017-10-09 13:21 ` [PATCH workqueue/for-4.14-fixes] workqueue: replace pool->manager_arb mutex with a flag Tejun Heo
2017-10-09 14:21 ` Boqun Feng
2017-10-09 14:47 ` Tejun Heo
2017-10-09 15:02 ` Lai Jiangshan
2017-10-09 15:08 ` Tejun Heo [this message]
2017-10-09 15:14 ` Lai Jiangshan
2017-10-09 15:33 ` Tejun Heo
2017-10-09 15:04 ` [PATCH v2 " Tejun Heo
2017-10-10 9:55 ` Lai Jiangshan
2017-10-10 14:15 ` Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171009150808.GD3301751@devbig577.frc2.facebook.com \
--to=tj@kernel.org \
--cc=boqun.feng@gmail.com \
--cc=jiangshanlai@gmail.com \
--cc=josef@toxicpanda.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox