Messages in this thread Patch in this message | | | Date | Thu, 5 Feb 2015 11:28:05 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH v2] ARM: Don't use complete() during __cpu_die |
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Hi Russell,
On Thu, Feb 05, 2015 at 10:50:35AM +0000, Russell King - ARM Linux wrote: > On Thu, Feb 05, 2015 at 11:14:30AM +0100, Krzysztof Kozlowski wrote: > > The complete() should not be used on offlined CPU. Rewrite the > > wait-complete mechanism with wait_on_bit_timeout(). > > Yuck. > > I think that the IPI idea would be far better, and a much smaller patch. > We can continue using the completions, but instead of running the > completion on the dying CPU, the dying CPU triggers an IPI which does > the completion on the requesting CPU.
This does look _much_ nicer than the bitmask approach.
[...]
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c > index 194df2f1aa87..c623e27a9c85 100644 > --- a/arch/arm/kernel/smp.c > +++ b/arch/arm/kernel/smp.c > @@ -73,6 +73,9 @@ enum ipi_msg_type { > IPI_IRQ_WORK, > IPI_COMPLETION, > IPI_CPU_BACKTRACE, > +#ifdef CONFIG_HOTPLUG_CPU > + IPI_CPU_DEAD, > +#endif > };
[...]
> static const char *ipi_types[NR_IPI] __tracepoint_string = { > #define S(x,s) [x] = s > S(IPI_WAKEUP, "CPU wakeup interrupts"),
We'll probably want to add an entry here ("CPU teardown interrupts"?), and bump NR_IPI in asm/hardirq.h.
Thanks, Mark.
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