Re: [PATCH] highres: Do not run the TIMER_SOFTIRQ after switchingto highres mode

From: Thomas Gleixner
Date: Sun Mar 04 2007 - 08:40:53 EST


On Sun, 2007-03-04 at 08:12 -0500, Andres Salomon wrote:
> Thomas Gleixner wrote:
> >>> The question is, how the tick timer gets enqueued in the softirq queue.
> >>> Can you isolate the codepath, where this happens ?
> >
> > The TIMER_SOFTIRQ runs the hrtimers during bootup until a usable
> > clocksource and clock event sources are registered. The switch to high
> > resolution mode happens inside of the TIMER_SOFTIRQ, but runs the
> > softirq afterwards. That way the tick emulation timer, which was set up
> > in the switch to highres might be executed in the softirq context, which
> > is a BUG. The rbtree has not to be touched by the softirq after the
> > highres switch.
> >
>
> And an additional request, just to make it explicit that we should not
> have any NO_SOFTIRQ callbacks in the tree; BUG out if we encounter such
> a thing.
>
> Signed-off-by: Andres Salomon <dilinger@xxxxxxxxxx>

Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>


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