Messages in this thread | | | Date | Tue, 14 Feb 2023 10:23:22 -0800 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return |
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On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daudé wrote: > Hi Josh, > > On 14/2/23 08:05, Josh Poimboeuf wrote: > > cpu_die() doesn't return. Make that more explicit with a BUG(). > > > > BUG() is preferable to unreachable() because BUG() is a more explicit > > failure mode and avoids undefined behavior like falling off the edge of > > the function into whatever code happens to be next. > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> > > --- > > arch/xtensa/kernel/smp.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c > > index 4dc109dd6214..7bad78495536 100644 > > --- a/arch/xtensa/kernel/smp.c > > +++ b/arch/xtensa/kernel/smp.c > > Can you update the documentation along? Currently we have: > > /* > * Called from the idle thread for the CPU which has been shutdown. > * > * Note that we disable IRQs here, but do not re-enable them > * before returning to the caller. This is also the behaviour > * of the other hotplug-cpu capable cores, so presumably coming > * out of idle fixes this. > */
void __ref cpu_die(void) { idle_task_exit(); local_irq_disable(); __asm__ __volatile__( " movi a2, cpu_restart\n" " jx a2\n");
BUG(); }
Hm, not only is the comment wrong, but it seems to be branching to cpu_restart? That doesn't seem right at all.
Max/Chris?
-- Josh
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