| Message ID | 20220713132843.49693-1-alvinzhan1234@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] arm64: Prevent offline CPU handling IRQs. | expand |
On Wed, Jul 13, 2022 at 09:28:43PM +0800, alvinzhan1234@gmail.com wrote: > From: Alvin Zhan <alvinzhan1234@gmail.com> > > Migrate all of the IRQs on this CPU after setting it offline may still cause > the IRQs to be dispatched to this CPU. I was under the impression that __cpu_disable() was called with interrupts masked, since it's called via stop_machine_cpuslocked(), and hence interrupts cannot be taken here (ignoring pseudo-NMIs for the moment). Have you ever seen that actually happen? Mark. > To prevent offline CPU handling IRQs, we should migrate the IRQs away from > this CPU before it is powered off. > > Signed-off-by: Alvin Zhan <alvinzhan1234@gmail.com> > --- > arch/arm64/kernel/smp.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index 62ed361a4..c4c3c5ed5 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -302,6 +302,11 @@ int __cpu_disable(void) > remove_cpu_topology(cpu); > numa_remove_cpu(cpu); > > + /* > + * Migrate IRQs away from this CPU first. > + */ > + irq_migrate_all_off_this_cpu(); > + > /* > * Take this CPU offline. Once we clear this, we can't return, > * and we must not schedule until we're ready to give up the cpu. > @@ -309,11 +314,6 @@ int __cpu_disable(void) > set_cpu_online(cpu, false); > ipi_teardown(cpu); > > - /* > - * OK - migrate IRQs away from this CPU > - */ > - irq_migrate_all_off_this_cpu(); > - > return 0; > } > > -- > 2.34.1 >
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 62ed361a4..c4c3c5ed5 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -302,6 +302,11 @@ int __cpu_disable(void) remove_cpu_topology(cpu); numa_remove_cpu(cpu); + /* + * Migrate IRQs away from this CPU first. + */ + irq_migrate_all_off_this_cpu(); + /* * Take this CPU offline. Once we clear this, we can't return, * and we must not schedule until we're ready to give up the cpu. @@ -309,11 +314,6 @@ int __cpu_disable(void) set_cpu_online(cpu, false); ipi_teardown(cpu); - /* - * OK - migrate IRQs away from this CPU - */ - irq_migrate_all_off_this_cpu(); - return 0; }