linux-kernel - Re: [PATCH 19/51] x86, therm_throt.c: Fix CPU hotplug callback registration

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Message-ID: <52F90C8C.9050203@linux.vnet.ibm.com>
Date:	Mon, 10 Feb 2014 22:59:48 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
CC:	paulus@...ba.org, rusty@...tcorp.com.au, peterz@...radead.org,
	tglx@...utronix.de, akpm@...ux-foundation.org, mingo@...nel.org,
	paulmck@...ux.vnet.ibm.com, tj@...nel.org, walken@...gle.com,
	ego@...ux.vnet.ibm.com, linux@....linux.org.uk,
	linux-kernel@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
	Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-edac@...r.kernel.org
Subject: Re: [PATCH 19/51] x86, therm_throt.c: Fix CPU hotplug callback registration

On 02/10/2014 09:23 PM, Oleg Nesterov wrote:
> On 02/06, Srivatsa S. Bhat wrote:
>>
>> --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
>> +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
>> @@ -319,7 +319,7 @@ static __init int thermal_throttle_init_device(void)
>>  	if (!atomic_read(&therm_throt_en))
>>  		return 0;
>>
>> -	register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
>> +	cpu_maps_update_begin();
>>
>>  #ifdef CONFIG_HOTPLUG_CPU
>>  	mutex_lock(&therm_cpu_lock);
>> @@ -333,6 +333,9 @@ static __init int thermal_throttle_init_device(void)
>>  	mutex_unlock(&therm_cpu_lock);
>>  #endif
>>
>> +	__register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
>> +	cpu_maps_update_done();
> 
> 
> Off-topic, but it seems that after this change therm_cpu_lock can die.
> Of course this needs another patch (if I am right).
> 

I'm not sure I understood that clearly. Can you please explain?

I'm guessing that you are referring to some problem with the #ifdef
CONFIG_HOTPLUG_CPU around mutex_lock/unlock(&therm_cpu_lock) ?

Regards,
Srivatsa S. Bhat

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