From 44424c34049f41123a3a8b4853822f47f4ff03a2 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Tue, 30 Jul 2013 23:09:46 +0100 Subject: [PATCH] ARM: 7803/1: 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. Reported-by: Sundarajan Srinivasan Signed-off-by: Stephen Boyd Signed-off-by: Russell King --- arch/arm/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index d3ca4f6915af..08b47ebd3144 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -197,6 +197,7 @@ void machine_shutdown(void) */ void machine_halt(void) { + local_irq_disable(); smp_send_stop(); local_irq_disable(); @@ -211,6 +212,7 @@ void machine_halt(void) */ void machine_power_off(void) { + local_irq_disable(); smp_send_stop(); if (pm_power_off) @@ -230,6 +232,7 @@ void machine_power_off(void) */ void machine_restart(char *cmd) { + local_irq_disable(); smp_send_stop(); arm_pm_restart(reboot_mode, cmd); -- 2.11.0