[PATCH v9 3/3] ARM: Check if a CPU has gone offline
From: Ashwin Chaugule <hidden>
Date: 2014-05-07 14:27:27
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
PSCIv0.2 adds a new function called AFFINITY_INFO, which can be used to query if a specified CPU has actually gone offline. Calling this function via cpu_kill ensures that a CPU has quiesced after a call to cpu_die. Signed-off-by: Ashwin Chaugule <redacted> Reviewed-by: Rob Herring <robh@kernel.org> --- arch/arm/kernel/psci_smp.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
diff --git a/arch/arm/kernel/psci_smp.c b/arch/arm/kernel/psci_smp.c
index 570a48c..502e6cf 100644
--- a/arch/arm/kernel/psci_smp.c
+++ b/arch/arm/kernel/psci_smp.c@@ -16,6 +16,8 @@ #include <linux/init.h> #include <linux/smp.h> #include <linux/of.h> +#include <linux/delay.h> +#include <uapi/linux/psci.h> #include <asm/psci.h> #include <asm/smp_plat.h>
@@ -66,6 +68,34 @@ void __ref psci_cpu_die(unsigned int cpu) /* We should never return */ panic("psci: cpu %d failed to shutdown\n", cpu); } + +int __ref psci_cpu_kill(unsigned int cpu) +{ + int err, i; + + if (!psci_ops.affinity_info) + return 1; + /* + * cpu_kill could race with cpu_die and we can + * potentially end up declaring this cpu undead + * while it is dying. So, try again a few times. + */ + + for (i=0; i<10; i++) { + err = psci_ops.affinity_info(cpu_logical_map(cpu), 0); + if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) + return 1; + + msleep(10); + pr_info("Retrying again to check for CPU kill\n"); + } + + pr_err("psci: Cannot kill CPU:%d, psci ret val: %d\n", + cpu, err); + /* Make platform_cpu_kill() fail. */ + return 0; +} + #endif bool __init psci_smp_available(void)
@@ -78,5 +108,6 @@ struct smp_operations __initdata psci_smp_ops = { .smp_boot_secondary = psci_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU .cpu_die = psci_cpu_die, + .cpu_kill = psci_cpu_kill, #endif };
--
1.8.3.2