Messages in this thread | | | Date | Tue, 30 Jul 2013 15:12:31 -0700 | From | Stephen Boyd <> | Subject | Re: [PATCH v2] ARM: Fix deadlock scenario with smp_send_stop() |
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On 07/24/13 13:36, Stephen Boyd wrote: > 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> > ---
Ok I threw this into the patch tracker because there were no more comments.
> Changes since v1: > - Use local_irq_disable() instead of preempt_disable() > > arch/arm/kernel/process.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c > index d3ca4f6..08b47eb 100644 > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -197,6 +197,7 @@ void machine_shutdown(void) > */ > void machine_halt(void) > { > + local_irq_disable(); > smp_send_stop(); > > local_irq_disable(); > @@ -211,6 +212,7 @@ void machine_halt(void) > */ > void machine_power_off(void) > { > + local_irq_disable(); > smp_send_stop(); > > if (pm_power_off) > @@ -230,6 +232,7 @@ void machine_power_off(void) > */ > void machine_restart(char *cmd) > { > + local_irq_disable(); > smp_send_stop(); > > arm_pm_restart(reboot_mode, cmd);
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