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arm64: Fix deadlock scenario with smp_send_stop()

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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>
(cherry picked from commit b9acc49ee9)

Conflicts:
	arch/arm64/kernel/process.c
This commit is contained in:
Arun KS
2014-05-07 02:41:23 +01:00
committed by Huang, Tao
parent 363aaed735
commit a3017b51a3
1 changed files with 3 additions and 2 deletions
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5
arch/arm64/kernel/process.c
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@@ -123,6 +123,7 @@ void machine_shutdown(void)
*/
void machine_halt(void)
{
local_irq_disable();
smp_send_stop();
while (1);
}
@@ -135,6 +136,7 @@ void machine_halt(void)
*/
void machine_power_off(void)
{
local_irq_disable();
smp_send_stop();
if (pm_power_off)
pm_power_off();
@@ -153,11 +155,10 @@ void machine_power_off(void)
*/
void machine_restart(char *cmd)
{
smp_send_stop();
/* Disable interrupts first */
local_irq_disable();
local_fiq_disable();
smp_send_stop();
/* Now call the architecture specific reboot code. */
if (arm_pm_restart)