linux-kernel - RE: [PATCH 1/3] alarmtimer: Replace the spinlock rtcdev

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Message-ID: <27240C0AC20F114CBF8149A2696CBE4A1B9C8A@SHSMSX101.ccr.corp.intel.com>
Date:	Thu, 1 Nov 2012 00:02:13 +0000
From:	"Liu, Chuansheng" <chuansheng.liu@...el.com>
To:	Oliver Neukum <oneukum@...e.de>
CC:	"john.stultz@...aro.org" <john.stultz@...aro.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/3] alarmtimer: Replace the spinlock rtcdev_lock with
 mutex



> -----Original Message-----
> From: Oliver Neukum [mailto:oneukum@...e.de]
> Sent: Wednesday, October 31, 2012 5:03 PM
> To: Liu, Chuansheng
> Cc: john.stultz@...aro.org; tglx@...utronix.de; gregkh@...uxfoundation.org;
> linux-kernel@...r.kernel.org; Liu, Chuansheng
> Subject: Re: [PATCH 1/3] alarmtimer: Replace the spinlock rtcdev_lock with
> mutex
> 
> On Thursday 01 November 2012 00:20:55 Chuansheng Liu wrote:
> > When do code reviewing, found no special requirement to
> > use spin_lock_irqsave/spin_unlock_irqrestore, because
> > alarmtimer_get_rtcdev() is called by posix clock interface.
> > So would like to use mutex to replace it.
> 
> What is gained thereby?
spin_lock_irqsave will disable the preempt and local irq, it is expensive than
mutex. Thanks.
> 
> 	Regards
> 		Oliver

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