Commit 44424c34 authored by Stephen Boyd's avatar Stephen Boyd Committed by Russell King

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()
 <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.
Reported-by: default avatarSundarajan Srinivasan <sundaraj@codeaurora.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 067e710b
...@@ -197,6 +197,7 @@ void machine_shutdown(void) ...@@ -197,6 +197,7 @@ void machine_shutdown(void)
*/ */
void machine_halt(void) void machine_halt(void)
{ {
local_irq_disable();
smp_send_stop(); smp_send_stop();
local_irq_disable(); local_irq_disable();
...@@ -211,6 +212,7 @@ void machine_halt(void) ...@@ -211,6 +212,7 @@ void machine_halt(void)
*/ */
void machine_power_off(void) void machine_power_off(void)
{ {
local_irq_disable();
smp_send_stop(); smp_send_stop();
if (pm_power_off) if (pm_power_off)
...@@ -230,6 +232,7 @@ void machine_power_off(void) ...@@ -230,6 +232,7 @@ void machine_power_off(void)
*/ */
void machine_restart(char *cmd) void machine_restart(char *cmd)
{ {
local_irq_disable();
smp_send_stop(); smp_send_stop();
arm_pm_restart(reboot_mode, cmd); arm_pm_restart(reboot_mode, cmd);
......
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