On 19 February 2015 at 14:14, Simon Horman <[email protected]> wrote: > On Wed, Feb 18, 2015 at 03:27:57PM -0800, Stephen Boyd wrote: >> On 02/18/15 14:27, Simon Horman wrote: >> > 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 <[email protected]> >> >> Cc: Nicolas Pitre <[email protected]> >> >> Cc: Dave Martin <[email protected]> >> >> Cc: Simon Horman <[email protected]> >> >> Cc: Magnus Damm <[email protected]> >> >> Cc: <[email protected]> >> >> Signed-off-by: Stephen Boyd <[email protected]> >> >> --- >> >> >> >> 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. >> >> Are you saying two (three?) patches to add the op, and then move over >> each struct smp_operations? It's all going through rmk's tree so I'll >> leave that up to him. > > I'm also happy to let RMK to decide what he thinks is best.
Apologies for bringing up an older thread, but was this change ever picked up? I recently hit this issue when I was running the kselftest suite (specifically the cpu-hotplug test case) on the ARM boards from kernelci.org. I don't see it in -next so I've tested the core changes and confirmed it the fixes the cpu-hotplug behavior on platforms that do not support it. > > _______________________________________________ > linux-arm-kernel mailing list > [email protected] > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel - Tyler -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
