linux-kernel - Re: [PATCH V1 Resend 2/5] tick-common: don't check tick_oneshot_mode_active() from tick_check

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Date:	Tue, 15 Apr 2014 20:30:35 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Viresh Kumar <viresh.kumar@...aro.org>
cc:	linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
	fweisbec@...il.com, Arvind.Chauhan@....com,
	linaro-networking@...aro.org
Subject: Re: [PATCH V1 Resend 2/5] tick-common: don't check tick_oneshot_mode_active()
 from tick_check_preferred()

On Tue, 15 Apr 2014, Viresh Kumar wrote:

> If 'curdev' passed to tick_check_preferred() is the current clock_event_device
> then these two checks look exactly same, because td->mode is set to
> TICKDEV_MODE_ONESHOT only when the event device has ONESHOT feature.
> 
> 	if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT))
> 		return false;
> 
> 	if (tick_oneshot_mode_active())
> 		return false;
> 
> Now left the case where 'curdev' is not the current clock_event_device. This can
> happen from the sequence started from clockevents_replace(). Here we are trying
> to find the best possible device that we should choose. And so even in this case
> we don't need the above check as we aren't really worried about the current
> device.

Wrong. If curdev is NULL, you might select a device w/o ONESHOT if the
system is in oneshot mode. Go figure.
 
Thanks,

	tglx
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