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From: Byungchul Park <byungchul.park@lge.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Byungchul Park <max.byungchul.park@gmail.com>,
	Ingo Molnar <mingo@kernel.org>, Tejun Heo <tj@kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	david@fromorbit.com, Johannes Berg <johannes@sipsolutions.net>,
	oleg@redhat.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	kernel-team@lge.com
Subject: Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation
Date: Tue, 5 Sep 2017 17:57:27 +0900	[thread overview]
Message-ID: <20170905085727.GV3240@X58A-UD3R> (raw)
In-Reply-To: <20170905071930.h6t2f4guvmswibnv@hirez.programming.kicks-ass.net>

On Tue, Sep 05, 2017 at 09:19:30AM +0200, Peter Zijlstra wrote:
> On Tue, Sep 05, 2017 at 09:08:25AM +0200, Peter Zijlstra wrote:
> > So you worry about max_active==1 ? Or you worry about pool->lock or
> > about the thread setup? I'm still not sure.
> 
> So the thing about pool->lock is that its a leaf lock, we take nothing

I think the following sentence is a key, I hope...

Leaf locks can also create dependecies with *crosslocks*. These
dependencies are not built between holding locks like typical locks.

> inside it. Futhermore its a spinlock and therefore blocking things like
> completions or page-lock cannot form a deadlock with it.

I agree. Now we should be only interested in blocking things.

> It is also fully isolated inside workqueue.c and easy to audit.
> 
> This is why I really can't be arsed about it.
> 
> And the whole setup stuff isn't properly preserved between works in any
> case, only the first few works would ever see that history, so why
> bother.

As I said in another reply, what about (1), (3) and (5) in my example?

  reply	other threads:[~2017-09-05  8:57 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-23 11:58 [PATCH 0/4] workqueue and lockdep stuffs Peter Zijlstra
2017-08-23 11:58 ` [PATCH 1/4] workqueue: Use TASK_IDLE Peter Zijlstra
2017-08-23 13:31   ` Tejun Heo
2017-08-23 11:58 ` [PATCH 2/4] lockdep/selftests: Add mixed read-write ABBA tests Peter Zijlstra
2017-08-23 11:58 ` [PATCH 3/4] workqueue/lockdep: Fix flush_work() annotation Peter Zijlstra
2017-08-23 11:58 ` [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation Peter Zijlstra
2017-08-24  2:18   ` Byungchul Park
2017-08-24 14:02     ` Peter Zijlstra
2017-08-25  1:11       ` Byungchul Park
2017-08-29  8:59         ` Peter Zijlstra
2017-08-29 14:23           ` [tip:locking/core] locking/lockdep: Untangle xhlock history save/restore from task independence tip-bot for Peter Zijlstra
2017-08-29 16:02           ` [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation Byungchul Park
2017-08-29 18:47             ` Peter Zijlstra
2017-08-30  2:09           ` Byungchul Park
2017-08-30  7:41             ` Byungchul Park
2017-08-30  8:53               ` Peter Zijlstra
2017-08-30  9:01                 ` Byungchul Park
2017-08-30  9:12                   ` Peter Zijlstra
2017-08-30  9:14                     ` Peter Zijlstra
2017-08-30  9:35                       ` Byungchul Park
2017-08-30  9:24                     ` Byungchul Park
2017-08-30 11:25                       ` Byungchul Park
2017-08-30 12:49                         ` Byungchul Park
2017-08-31  7:26                         ` Byungchul Park
2017-08-31  8:04                         ` Peter Zijlstra
2017-08-31  8:15                           ` Byungchul Park
2017-08-31  8:34                             ` Peter Zijlstra
2017-09-01  2:05                               ` Byungchul Park
2017-09-01  9:47                                 ` Peter Zijlstra
2017-09-01 10:16                                   ` Byungchul Park
2017-09-01 12:09                                     ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-01 12:38                                     ` Peter Zijlstra
2017-09-01 13:51                                       ` Byungchul Park
2017-09-01 16:38                                         ` Peter Zijlstra
2017-09-04  1:30                                           ` Byungchul Park
2017-09-04  2:08                                             ` Byungchul Park
2017-09-04 11:42                                             ` Peter Zijlstra
2017-09-05  0:38                                               ` Byungchul Park
2017-09-05  7:08                                                 ` Peter Zijlstra
2017-09-05  7:19                                                   ` Peter Zijlstra
2017-09-05  8:57                                                     ` Byungchul Park [this message]
2017-09-05  9:36                                                       ` Peter Zijlstra
2017-09-05 10:31                                                         ` Byungchul Park
2017-09-05 10:52                                                           ` Peter Zijlstra
2017-09-05 11:24                                                             ` Byungchul Park
2017-09-05 10:58                                                           ` Byungchul Park
2017-09-05 13:46                                                             ` Peter Zijlstra
2017-09-05 23:52                                                               ` Byungchul Park
2017-09-06  0:42                                                                 ` Boqun Feng
2017-09-06  1:32                                                                   ` Byungchul Park
2017-09-06 23:59                                                                     ` Byungchul Park
2017-09-07  0:11                                                                     ` Byungchul Park
2017-09-06  0:48                                                               ` Byungchul Park
2017-09-05  8:30                                                   ` Byungchul Park
2017-08-31  8:07                       ` Peter Zijlstra
2017-08-25  4:39       ` Byungchul Park
2017-08-29  6:46   ` Byungchul Park
2017-08-29  9:01     ` Peter Zijlstra
2017-08-29 16:12       ` Byungchul Park
2017-08-23 13:32 ` [PATCH 0/4] workqueue and lockdep stuffs Tejun Heo
2017-08-23 13:45   ` Peter Zijlstra

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