Re: [PATCH v2 0/2] ia64: prevent irq migration race in __cpu_disable path

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Mon, Feb 09, 2009 at 11:13:38AM -0700, Alex Chiang wrote:
> This is v2 of my attempt to prevent an oops while offlining CPUs.
> 
> The change is that the patch becomes a full revert of Paul's
> original patch, along with a long changelog that explains the
> situation as best as I can determine. It's not 100% satisfactory
> to me right now, but the testing we've done supports the patch.
> 
> The 2nd patch in the series is mostly cosmetic, and removes a
> redundant call to cpu_clear() that we no longer need().
> 
> Tony, if you agree with the rationale in 1/2, then this series is
> a candidate for .29.
> 
> stable team, if Tony pushes upstream for .29, then this series
> should be applied to the .27 and .28 stable series.

OK, I'll bite...

Why not use cpu_active_map rather than cpu_online_map to select which
CPU to migrate interrupts to?  That way, we can delay clearing the
bit in cpu_online_map and avoid the questionable scenario where irqs
are being handled by a CPU that appears to be offline.

							Thanx, Paul