Messages in this thread | | | Subject | Re: [PATCH] prevent powerpc from invoking irq handlers on offline CPUs | From | Benjamin Herrenschmidt <> | Date | Mon, 01 Sep 2008 13:14:40 +1000 |
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On Sun, 2008-08-31 at 19:06 -0700, Paul E. McKenney wrote: > On Mon, Sep 01, 2008 at 10:34:44AM +1000, Benjamin Herrenschmidt wrote: > > On Sun, 2008-08-31 at 10:31 -0700, Paul E. McKenney wrote: > > > Make powerpc refrain from clearing a given to-be-offlined CPU's bit in the > > > cpu_online_mask until it has processed pending irqs. This change > > > prevents other CPUs from being blindsided by an apparently offline CPU > > > nevertheless changing globally visible state. > > > > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > --- > > > > Sounds reasonable... the only possible worry here is if somebody tries > > an IPI ... The IPI code will and the target CPU mask with the online > > map, so it may try to send to the to-be-offlined CPU and timeout, no ? > > OK. Do we need separate IPI and online masks?
Shouldn't we already have routed all interrupts to other CPUs anyway ?
IE. The affinity of all interrupts should have been updated. So the only thing we're going to get here are possibly IPIs and decrementer, I don't see it being a big deal making sure we test we are online when receiving it.
Ben.
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