Messages in this thread | | | Date | Wed, 18 Feb 2015 17:27:31 -0500 | From | Simon Horman <> | Subject | Re: [PATCH v3] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable |
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On Fri, Feb 13, 2015 at 04:42:54PM -0800, 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 current users use the op to > indicate if a CPU can be hotplugged or not in a static fashion. > With PSCI we may need to introduce 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 1, 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> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > --- > > Changes since v2: > * Left cpu_disable op in place > * Split out shmobile function deletion > > arch/arm/common/mcpm_platsmp.c | 12 ++++-------- > arch/arm/include/asm/smp.h | 10 ++++++++++ > arch/arm/kernel/setup.c | 2 +- > arch/arm/kernel/smp.c | 15 ++++++++++++++- > arch/arm/mach-shmobile/common.h | 2 +- > arch/arm/mach-shmobile/platsmp.c | 4 ++-- > arch/arm/mach-shmobile/smp-r8a7790.c | 2 +- > arch/arm/mach-shmobile/smp-r8a7791.c | 2 +- > arch/arm/mach-shmobile/smp-sh73a0.c | 2 +- > 9 files changed, 35 insertions(+), 16 deletions(-)
I think it would make sense to separate the ARM-core changes from the mach-shmobile integration changes.
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