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From: Johannes Berg <johannes@sipsolutions.net>
To: Bart Van Assche <bvanassche@acm.org>, Tejun Heo <tj@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	"tytso@mit.edu" <tytso@mit.edu>
Subject: Re: [PATCH 0/3] Suppress false positives triggered by workqueue lockdep annotations
Date: Thu, 25 Oct 2018 17:27:28 +0200	[thread overview]
Message-ID: <8e7bac982621666375c2f5698e995f443343b3ad.camel@sipsolutions.net> (raw)
In-Reply-To: <20181025150540.259281-1-bvanassche@acm.org>

Hi Bart,

> In my tests with kernel v4.19 I noticed that several new false positive
> reports were generated by the workqueue lockdep annotations. This patch
> series addresses one of these false positives.

I tried my best to explain why they're not false positives as far as
lockdep is concerned, so I'd appreciate if you could address *why* you
actually think they are such.

I can understand that they are false positives as far as the code
*causing* this is concerned, but this isn't how lockdep works. It
generally tracks any dependency between "locks" (timers also, btw.) at
any time, to later be able to find issues.

This, however, should be solved at the places that actually show the
problem, not by making the lockdep annotations less powerful.

johannes



  parent reply	other threads:[~2018-10-25 15:27 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-25 15:05 Bart Van Assche
2018-10-25 15:05 ` [PATCH 1/3] kernel/workqueue: Remove lockdep annotation from __flush_work() Bart Van Assche
2018-10-25 15:31   ` Johannes Berg
2018-10-25 15:57     ` Johannes Berg
2018-10-25 16:01     ` Bart Van Assche
2018-10-25 15:05 ` [PATCH 2/3] kernel/workqueue: Surround work execution with shared lock annotations Bart Van Assche
2018-10-25 16:53   ` Johannes Berg
2018-10-25 17:22     ` Bart Van Assche
2018-10-25 19:17       ` Johannes Berg
2018-10-25 15:05 ` [PATCH 3/3] kernel/workqueue: Suppress a false positive lockdep complaint Bart Van Assche
2018-10-25 15:34   ` Johannes Berg
2018-10-25 15:55     ` Bart Van Assche
2018-10-25 19:59       ` Johannes Berg
2018-10-25 20:21         ` Theodore Y. Ts'o
2018-10-25 20:26           ` Johannes Berg
2018-10-25 15:36   ` Tejun Heo
2018-10-25 15:37     ` Tejun Heo
2018-10-25 20:13     ` Johannes Berg
2018-10-25 15:40   ` Theodore Y. Ts'o
2018-10-25 17:02   ` Johannes Berg
2018-10-25 17:11     ` Bart Van Assche
2018-10-25 19:51       ` Johannes Berg
2018-10-25 20:39         ` Bart Van Assche
2018-10-25 20:47           ` Johannes Berg
2018-10-25 15:27 ` Johannes Berg [this message]
2018-10-25 15:47   ` [PATCH 0/3] Suppress false positives triggered by workqueue lockdep annotations Bart Van Assche

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