Messages in this thread | | | Date | Sat, 5 Jul 2014 19:10:15 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] machine_power_off: not only local_irq_disable but also do disable preemption |
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On Sat, Jul 05, 2014 at 10:44:41PM +0530, pawandeep oza wrote: > 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
Please explain how that <PREEMPT> occurs with IRQs already disabled.
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