CC'ing linux-arch, so the arch folks can scream murder if they have
any objections.
On Tue, 19 Feb 2013, Frederic Weisbecker wrote:
> 2013/2/18 Thomas Gleixner <tglx@xxxxxxxxxxxxx>:
> > On Mon, 18 Feb 2013, Frederic Weisbecker wrote:
> >> diff --git a/kernel/softirq.c b/kernel/softirq.c
> >> index ed567ba..69fbefd 100644
> >> --- a/kernel/softirq.c
> >> +++ b/kernel/softirq.c
> >> @@ -277,6 +277,17 @@ restart:
> >> tsk_restore_flags(current, old_flags, PF_MEMALLOC);
> >> }
> >>
> >> +#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
> >
> > We really should get rid of that and make irqs disabled on irq exit
> > mandatory.
>
> Until now I even thought that having irqs disabled in irq_exit() was
> mandatory. I need to have a second look at tick_nohz_irq_exit() as I
> modified it with this requirement in mind...
Duh.
> Also with this patch, if a nesting interrupt happens right after
> tick_nohz_irq_exit(), this new irq will call tick_nohz_stop_idle() but
> not tick_nohz_start_idle() on the end. Leaving that unbalanced. I
> could work that around but I don't want to spaghettize further around
> that ifdef.
>
> So this patch actually does depend on __ARCH_IRQ_EXIT_IRQS_DISABLED. I
> need to convert all archs to force this first. Then think about the
> softirq.c cleanup once its done.
>
> I wonder what's the right path to this, may be loop over archs until
> they all have __ARCH_IRQ_EXIT_IRQS_DISABLED, then remove that? Sounds
> like non-sense but the safest way at the same time.
Yeah.
> >> static inline void invoke_softirq(void)
> >> {
> >> - if (!force_irqthreads) {
> >> + /* Can we run softirq's at all? We migth be nesting interrupts */
> >> + if (in_nesting_interrupt())
> >> + return;
> >
> > We might also be in a softirq disabled region where it makes no sense
> > to continue. So this should be
> >
> > in_nesting_interrupt() || in_softirq()
>
> in_nesting_interrupt() takes care of that as well.
Gah, misread the macro maze :(
Thanks,
tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-arch" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
