Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 04/13] xen/events: initialize local per-cpu mask for all possible events | Date | Mon, 26 Aug 2013 18:08:36 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: David Vrabel <david.vrabel@citrix.com>
commit 84ca7a8e45dafb49cd5ca90a343ba033e2885c17 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/xen/events.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -324,7 +324,7 @@ static void init_evtchn_cpu_bindings(voi for_each_possible_cpu(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)
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