linux-kernel - Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANrsvROa_ppmezwL9Se+jUVy_Yie+TMjP-s85Y==a9Ku4mqDYA@mail.gmail.com>
Date:   Thu, 7 Sep 2017 20:37:08 +0900
From:   Byungchul Park <max.byungchul.park@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Byungchul Park <byungchul.park@....com>, Tejun Heo <tj@...nel.org>,
        johannes.berg@...el.com, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, oleg@...hat.com,
        david@...morbit.com,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kernel-team@....com
Subject: Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush

On Thu, Sep 7, 2017 at 6:41 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Thu, Sep 07, 2017 at 09:33:16AM +0900, Byungchul Park wrote:
>> Workqueue added manual acquisitions to catch deadlock cases. Now
>> crossrelease was introduced, some of those are redundant because
>> crossrelease-enabled wait_for_completeion() also does it. Removed it.
>
> This does not explain how it doesn't become the regular timing dependent
> stuff cross-release normally is.

Yes, I will add more explanation for it at the next spin.

But, let me explain it a bit here to help you get it, since it's very
simple. This has nothing to do with 'might' thing I introduced
previously. For 'might' thing, I will start it after getting your response.

Here, I just removed acquire() because wait_for_completion()
already includes the acquire() by LOCKDEP_COMPLETIONS.
That's all.

-- 
Thanks,
Byungchul