Commit 84ca7a8e authored Aug 15, 2013 by David Vrabel Committed by Konrad Rzeszutek Wilk Aug 20, 2013

xen/events: initialize local per-cpu mask for all possible events



The sizeof() argument in init_evtchn_cpu_bindings() is incorrect
resulting in only the first 64 (or 32 in 32-bit guests) ports having
their bindings being initialized to VCPU 0.

In most cases this does not cause a problem as request_irq() will set
the irq affinity which will set the correct local per-cpu mask.
However, if the request_irq() is called on a VCPU other than 0, there
is a window between the unmasking of the event and the affinity being
set were an event may be lost because it is not locally unmasked on
any VCPU. If request_irq() is called on VCPU 0 then local irqs are
disabled during the window and the race does not occur.

Fix this by initializing all NR_EVENT_CHANNEL bits in the local
per-cpu masks.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: stable@vger.kernel.org

parent 3bc38cbc

drivers/xen/events.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -348,7 +348,7 @@ static void init_evtchn_cpu_bindings(void)

	for_each_possible_cpu(i)		for_each_possible_cpu(i)
	memset(per_cpu(cpu_evtchn_mask, i),		memset(per_cpu(cpu_evtchn_mask, i),
	(i == 0) ? ~0 : 0, sizeof(*per_cpu(cpu_evtchn_mask, i)));		(i == 0) ? ~0 : 0, NR_EVENT_CHANNELS/8);
	}		}

	static inline void clear_evtchn(int port)		static inline void clear_evtchn(int port)

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