# HG changeset patch
# User yamahata@xxxxxxxxxxxxx
# Node ID cc21edd631413b70d97f0defd20e7faa42237cdf
# Parent  ae245d35457b03f680b994437bd25532b98aa523
evtchn_do_upcall() has a micro optimization which is depends on
that xchg is a barrier.
However xchg of IA64 has acquire semantics so that event
channel notification is lost sometimes. This patch fixes it.
PATCHNAME: memory_barrier_evtchn_do_upcall

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

diff -r ae245d35457b -r cc21edd63141 linux-2.6-xen-sparse/drivers/xen/core/evtchn.c
--- a/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c	Wed Jun 28 13:59:29 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c	Fri Jun 30 10:44:54 2006 +0900
@@ -220,6 +220,9 @@ asmlinkage void evtchn_do_upcall(struct 
 	vcpu_info->evtchn_upcall_pending = 0;
 
 	/* NB. No need for a barrier here -- XCHG is a barrier on x86. */
+#ifndef CONFIG_X86
+	rmb();
+#endif
 	l1 = xchg(&vcpu_info->evtchn_pending_sel, 0);
 	while (l1 != 0) {
 		l1i = __ffs(l1);