On Sun, 1 Apr 2018 20:36:13 +1000 Nicholas Piggin <[email protected]> wrote:
> Use the NMI IPI rather than smp_call_function for smp_send_stop. > Have stopped CPUs hard disable interrupts rather than just soft > disable. > > This function is used in crash/panic/shutdown paths to bring other > CPUs down as quickly and reliably as possible, and minimizing their > potential to cause trouble. > > Avoiding the Linux smp_call_function infrastructure and (if supported) > using true NMI IPIs makes this more robust. > > Signed-off-by: Nicholas Piggin <[email protected]> > --- > arch/powerpc/kernel/smp.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > index cfc08b099c49..db88660bf6bd 100644 > --- a/arch/powerpc/kernel/smp.c > +++ b/arch/powerpc/kernel/smp.c > @@ -565,7 +565,11 @@ void crash_send_ipi(void (*crash_ipi_callback)(struct > pt_regs *)) > } > #endif > > +#ifdef CONFIG_NMI_IPI > +static void stop_this_cpu(struct pt_regs *regs) > +#else > static void stop_this_cpu(void *dummy) > +#endif > { > /* Remove this CPU */ > set_cpu_online(smp_processor_id(), false); > @@ -577,7 +581,11 @@ static void stop_this_cpu(void *dummy) > > void smp_send_stop(void) > { > +#ifdef CONFIG_NMI_IPI > + smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, stop_this_cpu, 1000000); I wonder if the delay_us should be a function of number of cpus and the callee should figure this out on its own? May be not in this series, but in the longer run. Balbir Singh.
