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