Messages in this thread | | | Subject | Re: PATCH: Fix race in cpu_down (hotplug cpu) | From | Nigel Cunningham <> | Date | Mon, 19 Sep 2005 16:31:36 +1000 |
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Hi.
On Mon, 2005-09-19 at 16:23, Srivatsa Vaddagiri wrote: > On Mon, Sep 19, 2005 at 04:11:11PM +1000, Nigel Cunningham wrote: > > > Ok, that makes sense. Nigel, could you confirm which idle routine you are > > > using? > > > > >From dmesg: > > > > monitor/mwait feature present. > > using mwait in idle threads. > > Ok, that may explain why __cpu_die is timing out for you! Can you try a > (untested, I am afraid) patch on these lines:
Will do. Given my (understandable I guess) difficulty in reproducing it reliably, shall I add a printk in there so I can see when it would have otherwise failed to drop out?
> --- process.c.org 2005-09-19 11:44:57.000000000 +0530 > +++ process.c 2005-09-19 11:48:28.000000000 +0530 > @@ -245,16 +245,18 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait); > */ > static void mwait_idle(void) > { > + int cpu = raw_smp_processor_id(); > + > local_irq_enable(); > > if (!need_resched()) { > set_thread_flag(TIF_POLLING_NRFLAG); > do { > __monitor((void *)¤t_thread_info()->flags, 0, 0); > - if (need_resched()) > + if (need_resched() || cpu_is_offline(cpu)) > break; > __mwait(0, 0); > - } while (!need_resched()); > + } while (!need_resched() || !cpu_is_offline(cpu));
Shouldn't this be !need_resched() && !cpu_is_offline(cpu)?
Regards,
Nigel
> clear_thread_flag(TIF_POLLING_NRFLAG); > } > } > > > Other idle routines will need similar fix. > > > Ok, but what about default_idle? > > default_idle should be fine as it is. IOW it should not cause __cpu_die to > timeout. --
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