linux-kernel - Re: [PATCH RT 1/2 v2] x86: Do not disable preemption in int3 on 32bit

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Message-ID: <4F215C5E.4090006@hitachi.com>
Date:	Thu, 26 Jan 2012 22:59:58 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org,
	linux-rt-users <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Carsten Emde <C.Emde@...dl.org>,
	John Kacur <jkacur@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Alexander van Heukelum <heukelum@...tmail.fm>,
	Andi Kleen <ak@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Clark Williams <williams@...hat.com>,
	Luis Goncalves <lgoncalv@...hat.com>
Subject: Re: [PATCH RT 1/2 v2] x86: Do not disable preemption in int3 on 32bit

(2012/01/26 22:33), Steven Rostedt wrote:
> On Thu, 2012-01-26 at 17:39 +0900, Masami Hiramatsu wrote:
>> (2012/01/25 23:32), Steven Rostedt wrote:
>>> Preemption must be disabled before enabling interrupts in do_trap
>>> on x86_64 because the stack in use for int3 and debug is a per CPU
>>> stack set by th IST. But in 32bit, the stack still belongs to the
>>> current task and there is no problem in scheduling out the task.
>>>
>>> Keep preemption enabled on X86_32 when enabling interrupts for
>>> do_trap().
>>>
>>> Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
>>
>> Hmm, I think you'd better change caller side, because the
>> function itself has "preempt" in its name. I think it can
>> easily mislead other people.
> 
> How about if we rename it to
> 
> conditional_preempt_sti/cli() ?
> 
> Then it can be both a conditional preempt as well as interrupts being
> disabled. The condition on preempt is "is 32 bits? don't preempt :
> preempt";

Better. If the functions are only for signaling, how
about using the "signal" in name? :)

conditional_sti/cli_for_signal()

Thanks,

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com
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