From: Stephen Boyd Date: Tue, 30 Jul 2013 22:09:46 +0000 (+0100) Subject: ARM: 7803/1: Fix deadlock scenario with smp_send_stop() X-Git-Tag: firefly_0821_release~5374 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=28650a80a69861af23ebb212cc1882df1e152b80;p=firefly-linux-kernel-4.4.55.git 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 --- diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 978002e5b406..d5768a7516f2 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -255,6 +255,7 @@ void machine_shutdown(void) */ void machine_halt(void) { + local_irq_disable(); smp_send_stop(); local_irq_disable(); @@ -269,6 +270,7 @@ void machine_halt(void) */ void machine_power_off(void) { + local_irq_disable(); smp_send_stop(); if (pm_power_off) @@ -288,6 +290,7 @@ void machine_power_off(void) */ void machine_restart(char *cmd) { + local_irq_disable(); smp_send_stop(); /* Flush the console to make sure all the relevant messages make it