diff options
| author | Stephen Boyd <sboyd@codeaurora.org> | 2015-07-29 00:34:48 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-07-31 18:58:30 +0100 |
| commit | 787047eea24a2443c366679ae6b5a3873a33b64e (patch) | |
| tree | 183659ffb653f2203ff81e7a1374973d8e18d251 /arch/arm/include/asm | |
| parent | 57853e8906a04a86c32fb96d8421b923c6d64162 (diff) | |
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 <mark.rutland@arm.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Acked-by: Simon Horman <horms@verge.net.au> [shmobile portion]
Tested-by: Simon Horman <horms@verge.net.au>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: <linux-sh@vger.kernel.org>
Tested-by: Tyler Baker <tyler.baker@linaro.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm')
| -rw-r--r-- | arch/arm/include/asm/smp.h | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/smp_plat.h | 9 |
2 files changed, 10 insertions, 0 deletions
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index 2f3ac1ba6fb4..318ce89eeff7 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -105,6 +105,7 @@ struct smp_operations { #ifdef CONFIG_HOTPLUG_CPU int (*cpu_kill)(unsigned int cpu); void (*cpu_die)(unsigned int cpu); + bool (*cpu_can_disable)(unsigned int cpu); int (*cpu_disable)(unsigned int cpu); #endif #endif diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h index 993e5224d8f7..f9080717fc88 100644 --- a/arch/arm/include/asm/smp_plat.h +++ b/arch/arm/include/asm/smp_plat.h @@ -107,4 +107,13 @@ static inline u32 mpidr_hash_size(void) extern int platform_can_secondary_boot(void); extern int platform_can_cpu_hotplug(void); +#ifdef CONFIG_HOTPLUG_CPU +extern int platform_can_hotplug_cpu(unsigned int cpu); +#else +static inline int platform_can_hotplug_cpu(unsigned int cpu) +{ + return 0; +} +#endif + #endif |