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

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Message-ID: <20170904013031.GM3240@X58A-UD3R>
Date:   Mon, 4 Sep 2017 10:30:32 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Byungchul Park <max.byungchul.park@...il.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 06:38:52PM +0200, Peter Zijlstra wrote:
> 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.

I keep asking you for an example because I really understand you.

   Fix my problematic example with your patches,

   or,

   Show me a problematic scenario with my original code, you expect.

Whatever, it would be helpful to understand you.