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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 /arch/arm/common
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>
Diffstat (limited to 'arch/arm/common')
-rw-r--r--arch/arm/common/mcpm_platsmp.c12
1 files changed, 4 insertions, 8 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
};