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authorStephen Boyd <sboyd@codeaurora.org>2015-07-29 00:34:48 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-07-31 18:58:30 +0100
commit787047eea24a2443c366679ae6b5a3873a33b64e (patch)
tree183659ffb653f2203ff81e7a1374973d8e18d251
parent57853e8906a04a86c32fb96d8421b923c6d64162 (diff)
downloadlinux-787047eea24a2443c366679ae6b5a3873a33b64e.tar.bz2
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>
-rw-r--r--arch/arm/common/mcpm_platsmp.c12
-rw-r--r--arch/arm/include/asm/smp.h1
-rw-r--r--arch/arm/include/asm/smp_plat.h9
-rw-r--r--arch/arm/kernel/setup.c2
-rw-r--r--arch/arm/kernel/smp.c15
-rw-r--r--arch/arm/mach-shmobile/common.h2
-rw-r--r--arch/arm/mach-shmobile/platsmp.c4
-rw-r--r--arch/arm/mach-shmobile/smp-r8a7790.c2
-rw-r--r--arch/arm/mach-shmobile/smp-r8a7791.c2
-rw-r--r--arch/arm/mach-shmobile/smp-sh73a0.c2
10 files changed, 35 insertions, 16 deletions
diff --git a/arch/arm/common/mcpm_platsmp.c b/arch/arm/common/mcpm_platsmp.c
index 92e54d7c6f46..2b25b6038f66 100644
--- a/arch/arm/common/mcpm_platsmp.c
+++ b/arch/arm/common/mcpm_platsmp.c
@@ -65,14 +65,10 @@ static int mcpm_cpu_kill(unsigned int cpu)
return !mcpm_wait_for_cpu_powerdown(pcpu, pcluster);
}
-static int mcpm_cpu_disable(unsigned int cpu)
+static bool mcpm_cpu_can_disable(unsigned int cpu)
{
- /*
- * We assume all CPUs may be shut down.
- * This would be the hook to use for eventual Secure
- * OS migration requests as described in the PSCI spec.
- */
- return 0;
+ /* We assume all CPUs may be shut down. */
+ return true;
}
static void mcpm_cpu_die(unsigned int cpu)
@@ -92,7 +88,7 @@ static struct smp_operations __initdata mcpm_smp_ops = {
.smp_secondary_init = mcpm_secondary_init,
#ifdef CONFIG_HOTPLUG_CPU
.cpu_kill = mcpm_cpu_kill,
- .cpu_disable = mcpm_cpu_disable,
+ .cpu_can_disable = mcpm_cpu_can_disable,
.cpu_die = mcpm_cpu_die,
#endif
};
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
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 36c18b73c1f4..6bbec6042052 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -1015,7 +1015,7 @@ static int __init topology_init(void)
for_each_possible_cpu(cpu) {
struct cpuinfo_arm *cpuinfo = &per_cpu(cpu_data, cpu);
- cpuinfo->cpu.hotpluggable = 1;
+ cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu);
register_cpu(&cpuinfo->cpu, cpu);
}
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 90dfbedfbfb8..3cd846f48eaf 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -175,13 +175,26 @@ static int platform_cpu_disable(unsigned int cpu)
if (smp_ops.cpu_disable)
return smp_ops.cpu_disable(cpu);
+ return 0;
+}
+
+int platform_can_hotplug_cpu(unsigned int cpu)
+{
+ /* cpu_die must be specified to support hotplug */
+ if (!smp_ops.cpu_die)
+ return 0;
+
+ if (smp_ops.cpu_can_disable)
+ return smp_ops.cpu_can_disable(cpu);
+
/*
* By default, allow disabling all CPUs except the first one,
* since this is special on a lot of platforms, e.g. because
* of clock tick interrupts.
*/
- return cpu == 0 ? -EPERM : 0;
+ return cpu != 0;
}
+
/*
* __cpu_disable runs on the processor to be shutdown.
*/
diff --git a/arch/arm/mach-shmobile/common.h b/arch/arm/mach-shmobile/common.h
index 476092b86c6e..8d27ec546a35 100644
--- a/arch/arm/mach-shmobile/common.h
+++ b/arch/arm/mach-shmobile/common.h
@@ -13,7 +13,7 @@ extern void shmobile_smp_boot(void);
extern void shmobile_smp_sleep(void);
extern void shmobile_smp_hook(unsigned int cpu, unsigned long fn,
unsigned long arg);
-extern int shmobile_smp_cpu_disable(unsigned int cpu);
+extern bool shmobile_smp_cpu_can_disable(unsigned int cpu);
extern void shmobile_boot_scu(void);
extern void shmobile_smp_scu_prepare_cpus(unsigned int max_cpus);
extern void shmobile_smp_scu_cpu_die(unsigned int cpu);
diff --git a/arch/arm/mach-shmobile/platsmp.c b/arch/arm/mach-shmobile/platsmp.c
index 3923e09e966d..b23378f3d7e1 100644
--- a/arch/arm/mach-shmobile/platsmp.c
+++ b/arch/arm/mach-shmobile/platsmp.c
@@ -31,8 +31,8 @@ void shmobile_smp_hook(unsigned int cpu, unsigned long fn, unsigned long arg)
}
#ifdef CONFIG_HOTPLUG_CPU
-int shmobile_smp_cpu_disable(unsigned int cpu)
+bool shmobile_smp_cpu_can_disable(unsigned int cpu)
{
- return 0; /* Hotplug of any CPU is supported */
+ return true; /* Hotplug of any CPU is supported */
}
#endif
diff --git a/arch/arm/mach-shmobile/smp-r8a7790.c b/arch/arm/mach-shmobile/smp-r8a7790.c
index 930f45cbc08a..947e437cab68 100644
--- a/arch/arm/mach-shmobile/smp-r8a7790.c
+++ b/arch/arm/mach-shmobile/smp-r8a7790.c
@@ -64,7 +64,7 @@ struct smp_operations r8a7790_smp_ops __initdata = {
.smp_prepare_cpus = r8a7790_smp_prepare_cpus,
.smp_boot_secondary = shmobile_smp_apmu_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
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
diff --git a/arch/arm/mach-shmobile/smp-sh73a0.c b/arch/arm/mach-shmobile/smp-sh73a0.c
index 2106d6b76a06..ae7c764fd6b4 100644
--- a/arch/arm/mach-shmobile/smp-sh73a0.c
+++ b/arch/arm/mach-shmobile/smp-sh73a0.c
@@ -68,7 +68,7 @@ struct smp_operations sh73a0_smp_ops __initdata = {
.smp_prepare_cpus = sh73a0_smp_prepare_cpus,
.smp_boot_secondary = sh73a0_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
- .cpu_disable = shmobile_smp_cpu_disable,
+ .cpu_can_disable = shmobile_smp_cpu_can_disable,
.cpu_die = shmobile_smp_scu_cpu_die,
.cpu_kill = shmobile_smp_scu_cpu_kill,
#endif