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()
<send IPI> handle_IPI()
disable_preemption/irqs
while(1);
<PREEMPT>
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 <sboyd@codeaurora.org>
Signed-off-by: Arun KS <getarunks@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index ed37c36..43b7c34 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -135,6 +135,7 @@
*/
void machine_halt(void)
{
+ local_irq_disable();
smp_send_stop();
while (1);
}
@@ -147,6 +148,7 @@
*/
void machine_power_off(void)
{
+ local_irq_disable();
smp_send_stop();
if (pm_power_off)
pm_power_off();
@@ -165,10 +167,9 @@
*/
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)