On Fri, 3 Feb 2017 21:45:24 +1000
Nicholas Piggin <npig...@gmail.com> wrote:
> On Tue, 20 Dec 2016 04:30:08 +1000
> Nicholas Piggin <npig...@gmail.com> wrote:
>
> > +static void do_smp_send_nmi_ipi(int cpu)
> > +{
> > + if (cpu >= 0) {
> > + do_message_pass(cpu, PPC_MSG_NMI_IPI);
> > + } else {
> > + unsigned int c;
> > +
> > + for_each_online_cpu(c) {
> > + if (c == raw_smp_processor_id())
> > + continue;
> > + do_message_pass(cpu, PPC_MSG_NMI_IPI);
>
> Okay this has a bug in the fallback path. Needs the following
> incremental patch. sysrq+x works okay with this (tested in mambo),
> and also recovers with "x" okay.
Also requires removal of get_online_cpus/put_online_cpus.
---
arch/powerpc/kernel/smp.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 81256522985d..e1a429251a7d 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -448,8 +448,6 @@ static int smp_send_nmi_ipi(int cpu, void (*fn)(struct
pt_regs *), u64 delay_us)
if (unlikely(!smp_ops))
return 0;
- get_online_cpus();
-
/* Take the nmi_ipi_busy count/lock with interrupts hard disabled */
nmi_ipi_lock_start(&flags);
while (nmi_ipi_busy_count) {
@@ -491,8 +489,6 @@ static int smp_send_nmi_ipi(int cpu, void (*fn)(struct
pt_regs *), u64 delay_us)
nmi_ipi_busy_count--;
nmi_ipi_unlock_end(&flags);
- put_online_cpus();
-
return ret;
}
#endif /* CONFIG_NMI_IPI */
--
2.11.0
