Re: [Xen-devel] [PATCH] linux-2.6.18/evtchn: clear secondary CPUs' cpu_evtchn_mask[] after restore

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 15.11.10 at 17:56, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> To bind all event channels to CPU#0, it is not sufficient to set all of
> its cpu_evtchn_mask[] bits; all other CPUs also need to get their bits
> cleared. Otherwise, evtchn_do_upcall() will start handling interrupts
> on CPUs they're not intended to run on, which can be particularly bad
> for per-CPU ones.

I believe this also needs to be fixed in the pv-ops sources.

Furthermore, while debugging this, I looked at pv-ops'
implementation of bind_evtchn_to_cpu(), and I suspect that the
use of __clear_bit() and __set_bit() isn't correct there - looking
over the call sites there doesn't appear to be a common serializing
spinlock. If so the underscore-less variants ought to be used.

Jan


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