From mboxrd@z Thu Jan 1 00:00:00 1970 From: ashwin.chaugule@linaro.org (Ashwin Chaugule) Date: Wed, 7 May 2014 10:27:27 -0400 Subject: [PATCH v9 3/3] ARM: Check if a CPU has gone offline In-Reply-To: <1399472847-14377-1-git-send-email-ashwin.chaugule@linaro.org> References: <1399472847-14377-1-git-send-email-ashwin.chaugule@linaro.org> Message-ID: <1399472847-14377-4-git-send-email-ashwin.chaugule@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Reviewed-by: Rob Herring --- 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 #include #include +#include +#include #include #include @@ -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