Messages in this thread | | | Date | Wed, 24 Jul 2013 13:29:00 -0700 | From | Stephen Boyd <> | Subject | Re: [PATCH] ARM: Fix deadlock scenario with smp_send_stop() |
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On 07/24/13 13:21, Russell King - ARM Linux wrote: > On Wed, Jul 24, 2013 at 11:56:18AM -0700, Stephen Boyd wrote: >> On 07/09, 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. >>> >>> Reported-by: Sundarajan Srinivasan <sundaraj@codeaurora.com> >>> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> >>> --- >>> >>> Resending this patch now that the context has changed. >> Ping? Shall I put this in the patch tracker? > Well, looking at x86, they use local_irq_disable() before sending the > stop, so I think we should do the same for cross-arch consistency.
Fair enough. I'll send v2 with that.
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