From 787047eea24a2443c366679ae6b5a3873a33b64e Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Wed, 29 Jul 2015 00:34:48 +0100 Subject: ARM: 8392/3: smp: Only expose /sys/.../cpuX/online if hotpluggable 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 Cc: Nicolas Pitre Cc: Dave Martin Acked-by: Simon Horman [shmobile portion] Tested-by: Simon Horman Cc: Magnus Damm Cc: Tested-by: Tyler Baker Cc: Geert Uytterhoeven Signed-off-by: Stephen Boyd Signed-off-by: Russell King --- arch/arm/mach-shmobile/smp-r8a7791.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm/mach-shmobile/smp-r8a7791.c') diff --git a/arch/arm/mach-shmobile/smp-r8a7791.c b/arch/arm/mach-shmobile/smp-r8a7791.c index 5e2d1db79afa..b2508c0d276b 100644 --- a/arch/arm/mach-shmobile/smp-r8a7791.c +++ b/arch/arm/mach-shmobile/smp-r8a7791.c @@ -58,7 +58,7 @@ struct smp_operations r8a7791_smp_ops __initdata = { .smp_prepare_cpus = r8a7791_smp_prepare_cpus, .smp_boot_secondary = r8a7791_smp_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU - .cpu_disable = shmobile_smp_cpu_disable, + .cpu_can_disable = shmobile_smp_cpu_can_disable, .cpu_die = shmobile_smp_apmu_cpu_die, .cpu_kill = shmobile_smp_apmu_cpu_kill, #endif -- cgit v1.2.3