xen: events: Make last processed event channel a per-cpu variable.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[ijc: forward ported from linux-2.6.18-xen.hg 325:b2768401db94]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 75cc6f50bd29..1fc3192468ef 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1026,6 +1026,8 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 }
 
 static DEFINE_PER_CPU(unsigned, xed_nesting_count);
+static DEFINE_PER_CPU(unsigned int, last_word_idx) = { BITS_PER_LONG - 1 };
+static DEFINE_PER_CPU(unsigned int, last_bit_idx) = { BITS_PER_LONG - 1 };
 
 /*
  * Mask out the i least significant bits of w
@@ -1043,8 +1045,6 @@ static DEFINE_PER_CPU(unsigned, xed_nesting_count);
  */
 static void __xen_evtchn_do_upcall(void)
 {
-        static unsigned int last_word_idx = BITS_PER_LONG - 1;
-        static unsigned int last_bit_idx = BITS_PER_LONG - 1;
         int word_idx, bit_idx;
         int cpu = get_cpu();
         struct shared_info *s = HYPERVISOR_shared_info;
@@ -1065,8 +1065,8 @@ static void __xen_evtchn_do_upcall(void)
 #endif
                 pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
 
-                word_idx = last_word_idx;
-                bit_idx = last_bit_idx;
+                word_idx = __this_cpu_read(last_word_idx);
+                bit_idx = __this_cpu_read(last_bit_idx);
 
                 while (pending_words != 0) {
                         unsigned long pending_bits;
@@ -1121,9 +1121,8 @@ static void __xen_evtchn_do_upcall(void)
                                  * If this is the final port processed, we'll
                                  * pick up here+1 next time.
                                  */
-                                last_word_idx = word_idx;
-                                last_bit_idx = bit_idx;
-
+                                __this_cpu_write(last_word_idx, word_idx);
+                                __this_cpu_write(last_bit_idx, bit_idx);
                         } while (bit_idx != BITS_PER_LONG - 1);
 
                         pending_bits = active_evtchns(cpu, s, word_idx);