From: Arun KS Date: Wed, 7 May 2014 01:41:23 +0000 (+0100) Subject: arm64: Fix deadlock scenario with smp_send_stop() X-Git-Tag: firefly_0821_release~4158^2~275 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a3017b51a38fd20da33f16ae33fdf33c3f2a3e43;p=firefly-linux-kernel-4.4.55.git 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 (cherry picked from commit b9acc49ee9464f8f8232a790045d057eb158e869) Conflicts: arch/arm64/kernel/process.c --- diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 94e13bc7dd9f..11094c8d1227 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -123,6 +123,7 @@ void machine_shutdown(void) */ void machine_halt(void) { + local_irq_disable(); smp_send_stop(); while (1); } @@ -135,6 +136,7 @@ void machine_halt(void) */ void machine_power_off(void) { + local_irq_disable(); smp_send_stop(); if (pm_power_off) pm_power_off(); @@ -153,11 +155,10 @@ void machine_power_off(void) */ void machine_restart(char *cmd) { - smp_send_stop(); - /* Disable interrupts first */ local_irq_disable(); local_fiq_disable(); + smp_send_stop(); /* Now call the architecture specific reboot code. */ if (arm_pm_restart)