Re: [PATCH] nohz: Make tick_nohz_irq_exit() irq safe
From: Thomas Gleixner
Date: Wed Feb 20 2013 - 18:16:01 EST
On Wed, 20 Feb 2013, Frederic Weisbecker wrote:
> 2013/2/20 Thomas Gleixner <tglx@xxxxxxxxxxxxx>:
> > That's not a fix. That's an hack.
> I know it looks that way. That's because it's a pure regression fix,
> minimal for backportability.
> I'm distinguishing two different things here: the fact that some archs
> can call irq_exit() with interrupts enabled which is a global design
> problem, and the fact that tick_nohz_irq_exit() was safe against that
> until 3.2 when I broke it with a commit of mine.
> My goal was basically to restore that protection in a minimal commit
> such that we can backport the regression fix, then deal with
> __ARCH_IRQ_EXIT_IRQS_DISABLED afterward, since it requires some more
> invasive changes.
> >> A saner long term solution will be to remove
> >> __ARCH_IRQ_EXIT_IRQS_DISABLED.
> > We really want to enforce that interrupt disabled condition for
> > calling irq_exit(). So why make this exclusive to tick_nohz_irq_exit()?
> I need a fix that I can backport. Is the below fine with a stable tag?
> It looks a bit too invasive for the single regression involved.
I think that's fine as it's obviously correct and not diluting the
real underlying issue of the __ARCH_IRQ_EXIT_IRQS_DISABLED insanity.
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