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Date: Tue, 26 Feb 2013 16:14:43 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Frederic Weisbecker <fweisbec@gmail.com>
cc: Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/2] irq: Cleanup context state transitions in
 irq_exit()
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On Tue, 26 Feb 2013, Frederic Weisbecker wrote:

> 2013/2/26 Thomas Gleixner <tglx@linutronix.de>:
> > On Fri, 22 Feb 2013, Linus Torvalds wrote:
> >> On Fri, Feb 22, 2013 at 7:06 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> >> >>
> >> >> I prefer to let you guys have the final word on this patch. Whether you
> >> >> apply it or not, I fear I'll never be entirely happy either way :)
> >> >> That's the sad fate of dealing with circular dependencies...
> >> >
> >> > plus the butt ugly softirq semantics or the lack thereof ...
> >>
> >> The softirq semantics are perfectly fine. Don't blame softirq for the
> >> fact that irq_exit() has had shit-for-brains for a long time.
> >>
> >> Just move the whole "invoke_softirq()" thing down to *after* the
> >> tick_nohz_irq_exit() stuff.
> >
> > We can't move tick_nohz_irq_exit() before invoke_softirq() simply
> > because we need to take the timers into account for NOHZ and those can
> > change when the softirq code runs.
> >
> > So no, we need an extra check after invoke_softirq() and the same is
> > true for RCU.
> 
> And what do you think about Linus's idea to move tick_nohz_irq_exit()
> to do_softirq()?
> This sounds feasible and a right place to do this, I hope that won't
> uglify do_softirq() though.
> I can try something.

Yeah, looks doable. the rcu stuff needs to go there as well, right?