linux-kernel - Re: [PATCH] Fix the race between smp_call

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Message-ID: <1331544767.18960.23.camel@twins>
Date:	Mon, 12 Mar 2012 10:32:47 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Liu, Chuansheng" <chuansheng.liu@...el.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Yanmin Zhang <yanmin_zhang@...ux.intel.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [PATCH] Fix the race between smp_call_function and CPU booting

On Mon, 2012-03-12 at 09:27 +0000, Liu, Chuansheng wrote:
> From: liu chuansheng <chuansheng.liu@...el.com>
> Subject: [PATCH] Fix the race between smp_call_function and CPU booting
> 
> When system is waking up from suspend state, sometimes the
> smp_call_function is called which will cause deadlock specially on the
> platform which just has two CPUs.
> 
> CPU0:                                           CPU1:
> pm_suspend -->
> suspend_devices_and_enter -->
> enable_nonboot_cpus -->
> _cpu_up -->
> __cpu_up -->
> native_cpu_up
>                                                 start_secondary
>                                                         -- set cpu online
>                                                         -- waiting for the active state new thread call:
> smp_call_function -->
> smp_call_function_many -->
> smp_call_function_single -->
>    -- csd_lock
>    -- generic_exec_single -->
>    -- arch_send_call_function_single_ipi
>    -- csd_lock_wait
> 
> At this time, both CPUs are blocked. Normally the CPU0 will set the
> CPU1 with active state after finished the _cpu_up calling, but CPU1
> can not handle the IPI due to the corresponding irq is still disabled,
> which will be enabled after waiting for the active state.
> 
> The solution is just to send smp call to active cpus instead of online
> cpus.

Wouldn't http://lkml.org/lkml/2011/12/15/255 also solve that?
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