ARM: 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.
Change-Id: I528af0b4448433bd9d6ca12d6a0e2c422a55d4be
CRs-Fixed: 396169
Reported-by: Sundarajan Srinivasan <sundaraj@codeaurora.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
(cherry picked from commit 78e9b56740ad789351b6d15cd9a67fe03091a3a1)
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 3616d46..0ff45bd 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -300,6 +300,7 @@
void machine_shutdown(void)
{
+ preempt_disable();
#ifdef CONFIG_SMP
/*
* Disable preemption so we're guaranteed to