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From: hpa@zytor.com (H. Peter Anvin)
To: Dave Jones <davej@redhat.com>,
	Rudolf Marek <r.marek@assembler.cz>,
	hpa@zytor.com, norsk5@xmission.com,
	lkml <linux-kernel@vger.kernel.org>,
	LM Sensors <lm-sensors@lm-sensors.org>,
	bluesmoke-devel@lists.sourceforge.net
Subject: [lm-sensors] [RFC] new MSR r/w functions per CPU
Date: Wed, 13 Dec 2006 22:19:52 +0000	[thread overview]
Message-ID: <45807C88.6060807@zytor.com> (raw)
In-Reply-To: <20061213221026.GF2418@redhat.com>

Dave Jones wrote:
> 
> Exposing the guts of the msr driver like that doesn't seem too clean.
> For in-kernel use, why not just add something like this..
> (note:not even compile tested)..
> 

Well, that *is* the guts of the MSR driver.

> void rdmsr_on_cpu(unsigned int cpu, unsigned long msr, unsigned long *lo, unsigned long *hi)
> {
>     cpumask_t oldmask;
> 
>     oldmask = current->cpus_allowed;
>     set_cpus_allowed(current, cpumask_of_cpu(cpu));
> 
> 	rdmsr(msr, &lo, &hi);
> 
>     set_cpus_allowed(current, oldmask);
> }
> 

[The above doesn't work, by the way.  This approach was discussed a long 
time ago, and vetoed due to the potential for deadlock.]

	-hpa


WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Dave Jones <davej@redhat.com>,
	Rudolf Marek <r.marek@assembler.cz>,
	hpa@zytor.com, norsk5@xmission.com,
	lkml <linux-kernel@vger.kernel.org>,
	LM Sensors <lm-sensors@lm-sensors.org>,
	bluesmoke-devel@lists.sourceforge.net
Subject: Re: [RFC] new MSR r/w functions per CPU
Date: Wed, 13 Dec 2006 14:19:52 -0800	[thread overview]
Message-ID: <45807C88.6060807@zytor.com> (raw)
In-Reply-To: <20061213221026.GF2418@redhat.com>

Dave Jones wrote:
> 
> Exposing the guts of the msr driver like that doesn't seem too clean.
> For in-kernel use, why not just add something like this..
> (note:not even compile tested)..
> 

Well, that *is* the guts of the MSR driver.

> void rdmsr_on_cpu(unsigned int cpu, unsigned long msr, unsigned long *lo, unsigned long *hi)
> {
>     cpumask_t oldmask;
> 
>     oldmask = current->cpus_allowed;
>     set_cpus_allowed(current, cpumask_of_cpu(cpu));
> 
> 	rdmsr(msr, &lo, &hi);
> 
>     set_cpus_allowed(current, oldmask);
> }
> 

[The above doesn't work, by the way.  This approach was discussed a long 
time ago, and vetoed due to the potential for deadlock.]

	-hpa

  reply	other threads:[~2006-12-13 22:19 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-13 21:45 [lm-sensors] [RFC] new MSR r/w functions per CPU Rudolf Marek
2006-12-13 21:45 ` Rudolf Marek
2006-12-13 22:01 ` [lm-sensors] " H. Peter Anvin
2006-12-13 22:01   ` H. Peter Anvin
2006-12-13 22:10 ` [lm-sensors] " Dave Jones
2006-12-13 22:10   ` Dave Jones
2006-12-13 22:19   ` H. Peter Anvin [this message]
2006-12-13 22:19     ` H. Peter Anvin
2006-12-13 22:26     ` [lm-sensors] " Dave Jones
2006-12-13 22:26       ` Dave Jones
2006-12-13 22:45       ` [lm-sensors] " H. Peter Anvin
2006-12-13 22:45         ` H. Peter Anvin

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