linux-kernel - Re: [PATCH 1/1 V2] workqueue: remove the del_timer_sync()s in maybe_create

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]

Date:	Mon, 14 Jul 2014 10:27:07 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/1 V2] workqueue: remove the del_timer_sync()s in
 maybe_create_worker()

Hello,

On Mon, Jul 14, 2014 at 04:13:21PM +0800, Lai Jiangshan wrote:
> It is said in the document that the timer which is being
> deleted by del_timer_sync() should not be restarted:
>   Synchronization rules: Callers must prevent restarting of
>   the timer, otherwise this function is meaningless.
> 
> Repeating timer may cause the del_timer_sync() spin longer,
> or even spin forever in very very very very extreme condition.

I'm fairly sure del_timer_sync() can delete self-requeueing timers.
The implementation busy-waits if the queued timer is the currently
executing one and dequeues only while the timer isn't running which
should be able to handle self-requeueing ones just fine.  Thomas,
del_timer_sync() can reliably delete self-requeueing ones, right?

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/