On Fri, Jan 17, 2020 at 12:16 PM Rob Landley <rob@xxxxxxxxxxx> wrote: > > On 1/14/20 5:06 AM, Hsin-Yi Wang wrote: > > This patch adds a config ARCH_OFFLINE_CPUS_ON_REBOOT, which would offline cpus in > > migrate_to_reboot_cpu(). If non reboot cpus are all offlined here, the loop for > > checking online cpus would be an empty loop. If architecture don't enable this > > config, or some cpus somehow fails to offline, it would fallback to ipi > > function. > > I'm curious: > > > +# Select to do a full offline on secondary CPUs before reboot. > > +config ARCH_OFFLINE_CPUS_ON_REBOOT > > + bool "Support for offline CPUs before reboot" > > + depends on HOTPLUG_CPU > > The new symbol can't be selected without the other symbol. > > > + select ARCH_OFFLINE_CPUS_ON_REBOOT if HOTPLUG_CPU > > And the other symbol automatically selects the new one. > > Why are you adding a second symbol that means the same thing as the existing symbol? > I should make the arch selecting this symbol in other patches and let the arch decides if they want to opt in, as Thomas pointed out in v5: https://lore.kernel.org/lkml/8736cgxmxi.fsf@xxxxxxxxxxxxxxxxxxxxxxx/ Current solution is not sufficient since it only solve problems for system that enables HOTPLUG_CPU. > > +#if defined(CONFIG_PM_SLEEP_SMP) || defined(CONFIG_ARCH_OFFLINE_CPUS_ON_REBOOT) > > +extern int freeze_secondary_cpus(int primary, bool reboot); > > +#endif > > Couldn't that just test HOTPLUG_CPU? What's the second symbol for? (You can have > empty stub functions when architectures don't support a thing...) > > Rob
