linux-kernel - Re: [PATCH 1/3] kernel/workqueue: Remove lockdep annotation from __flush

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Message-ID: <61f01315bbbec872d4173ca4a89ba0268d199aa3.camel@sipsolutions.net>
Date:   Thu, 25 Oct 2018 17:57:22 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Bart Van Assche <bvanassche@....org>, Tejun Heo <tj@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        "tytso@....edu" <tytso@....edu>
Subject: Re: [PATCH 1/3] kernel/workqueue: Remove lockdep annotation from
 __flush_work()

On Thu, 2018-10-25 at 17:31 +0200, Johannes Berg wrote:
> On Thu, 2018-10-25 at 15:05 +0000, Bart Van Assche wrote:
> > As documented in a comment in start_flush_work(), calling flush_work()
> > from a multi-threaded workqueue is safe if that workqueue is not
> > equipped with a rescuer. Avoid that flush_work() calls from inside a
> > work item executing on such a queue trigger a lockdep complaint.

So actually, come to think of it, certainly this will cause a false
negative in this case?

mutex_lock(A);
flush_work(W);

worker_W_function()
{
	mutex_lock(A);
}

right?

johannes