Messages in this thread | | | Date | Tue, 7 Apr 2015 15:56:35 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH v4] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable |
| |
On Mon, Apr 06, 2015 at 01:24:13PM -0700, Stephen Boyd wrote: > Writes to /sys/.../cpuX/online fail if we determine the platform > doesn't support hotplug for that CPU. Furthermore, if the cpu_die > op isn't specified the system hangs when we try to offline a CPU > and it comes right back online unexpectedly. Let's figure this > stuff out before we make the sysfs nodes so that the online file > doesn't even exist if it isn't (at least sometimes) possible to > hotplug the CPU. > > Add a new 'cpu_can_disable' op and repoint all 'cpu_disable' > implementations at it because all implementers use the op to > indicate if a CPU can be hotplugged or not in a static fashion. > With PSCI we may need to add a 'cpu_disable' op so that the > secure OS can be migrated off the CPU we're trying to hotplug. > In this case, the 'cpu_can_disable' op will indicate that all > CPUs are hotpluggable by returning true, but the 'cpu_disable' op > will make a PSCI migration call and occasionally fail, denying > the hotplug of a CPU. This shouldn't be any worse than x86 where > we may indicate that all CPUs are hotpluggable but occasionally > we can't offline a CPU due to check_irq_vectors_for_cpu_disable() > failing to find a CPU to move vectors to. > > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Nicolas Pitre <nico@linaro.org> > Cc: Dave Martin <Dave.Martin@arm.com> > Cc: Simon Horman <horms@verge.net.au> > Cc: Magnus Damm <magnus.damm@gmail.com> > Cc: <linux-sh@vger.kernel.org> > Cc: Tyler Baker <tyler.baker@linaro.org> > Cc: Geert Uytterhoeven <geert@linux-m68k.org> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
I think this is fine, but I'd like to see some acks for it. As it's mostly core ARM stuff, it should be merged through my tree unless there is a known conflict with arm-soc. Thanks.
-- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.
| |