linux-kernel - Re: [PATCH V2] smp: Give WARN()ing when calling smp_call_function

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 for Android: free password hash cracker in your pocket

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

Date:	Sun, 7 Jul 2013 15:47:12 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Wang YanQing <udknight@...il.com>
cc:	Chuansheng Liu <chuansheng.liu@...el.com>, mingo@...nel.org,
	peterz@...radead.org, jbeulich@...e.com,
	paulmck@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
	mina86@...a86.org, srivatsa.bhat@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org, jun.zhang@...el.com,
	fengguang.wu@...el.com
Subject: Re: [PATCH V2] smp: Give WARN()ing when calling smp_call_function_many()/single()
 in serving irq

On Sun, 7 Jul 2013, Wang YanQing wrote:
> On Fri, Jul 05, 2013 at 04:37:14PM +0200, Thomas Gleixner wrote:
> > Hmm, even there it matters, because of the following scenario:
> > 
> > CPU 0
> > smp_call_function_single(CPU 1)
> >     csd_lock(CPU 1)
> 
> No, smpl_call_function_single(CPU 1)
> will csd_lock(CPU 0), not csd_lock(CPU 1)
> 
> >     irq_enter()
> >     irq_exit()
> >     __do_softirq()
> >     smp_call_function_many()
> >       setup csd (CPU 1)
> >         csd_lock(CPU 1) ==> CPU 0 deadlocked itself.
> > 
> 
> maybe below is the scenario:
>      irq_enter()
>      irq_exit()
>      __do_softirq()
>      smp_call_function_single()
>        setup csd (CPU 1)
>          csd_lock(CPU 0) ==> CPU 0 deadlocked itself.

Right, I fatfingered that :)
--
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/