linux-kernel - Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation

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Date:   Fri, 1 Sep 2017 18:38:52 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Byungchul Park <max.byungchul.park@...il.com>
Cc:     Byungchul Park <byungchul.park@....com>,
        Ingo Molnar <mingo@...nel.org>, Tejun Heo <tj@...nel.org>,
        Boqun Feng <boqun.feng@...il.com>, david@...morbit.com,
        Johannes Berg <johannes@...solutions.net>, oleg@...hat.com,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kernel-team@....com
Subject: Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation

On Fri, Sep 01, 2017 at 10:51:48PM +0900, Byungchul Park wrote:
> On Fri, Sep 1, 2017 at 9:38 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> > On Fri, Sep 01, 2017 at 07:16:29PM +0900, Byungchul Park wrote:
> >
> >> It would be gone _only_ at the time the history overrun, and then it
> >> will be built again. So, you are wrong.
> 
> s/it will be built again/the acquisition will be added into the xhlock
> array again/
> 
> Now, better to understand?

No, I still don't get it. How are we ever going to get the workqueue
thread setup code back after its spooled out?

> > How will it ever be build again? You only ever spawn the worker thread
> > _ONCE_, then it runs lots and lots of works.
> >
> > We _could_ go fix it, but I really don't see it being worth the time and
> 
> We don't need to fix it spending time and effort. Just *revert* all your
> wrong patches.

And get tangled up with the workqueue annotation again, no thanks.
Having the first few works see the thread setup isn't worth it.

And your work_id annotation had the same problem.