From b9acc49ee9464f8f8232a790045d057eb158e869 Mon Sep 17 00:00:00 2001 From: Arun KS Date: Wed, 7 May 2014 02:41:23 +0100 Subject: [PATCH] arm64: Fix deadlock scenario with smp_send_stop() If one process calls sys_reboot and that process then stops other CPUs while those CPUs are within a spin_lock() region we can potentially encounter a deadlock scenario like below. CPU 0 CPU 1 ----- ----- spin_lock(my_lock) smp_send_stop() handle_IPI() disable_preemption/irqs while(1); spin_lock(my_lock) <--- Waits forever We shouldn't attempt to run any other tasks after we send a stop IPI to a CPU so disable preemption so that this task runs to completion. We use local_irq_disable() here for cross-arch consistency with x86. Based-on-work-by: Stephen Boyd Signed-off-by: Arun KS Signed-off-by: Catalin Marinas --- arch/arm64/kernel/process.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index ed37c3694cb8..43b7c34f92cb 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -135,6 +135,7 @@ void machine_shutdown(void) */ void machine_halt(void) { + local_irq_disable(); smp_send_stop(); while (1); } @@ -147,6 +148,7 @@ void machine_halt(void) */ void machine_power_off(void) { + local_irq_disable(); smp_send_stop(); if (pm_power_off) pm_power_off(); @@ -165,10 +167,9 @@ void machine_power_off(void) */ void machine_restart(char *cmd) { - smp_send_stop(); - /* Disable interrupts first */ local_irq_disable(); + smp_send_stop(); /* Now call the architecture specific reboot code. */ if (arm_pm_restart)