[Xen-changelog] [xen-unstable] x86/HPET: fix initialization order

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxxxx>
# Date 1299935942 0
# Node ID 87aa1277eae02fbafab3da4276fb9f9c7a8bdf26
# Parent  a8fee4ad3ad0650e7a5cc0fb253c6a0ada1ac583
x86/HPET: fix initialization order

At least the legacy path can enter its interrupt handler callout while
initialization is still in progress - that handler checks whether
->event_handler is non-NULL, and hence all other initialization must
happen before setting this field.

Do the same to the MSI initialization just in case (and to keep the
code in sync).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---


diff -r a8fee4ad3ad0 -r 87aa1277eae0 xen/arch/x86/hpet.c
--- a/xen/arch/x86/hpet.c       Fri Mar 11 18:22:23 2011 +0000
+++ b/xen/arch/x86/hpet.c       Sat Mar 12 13:19:02 2011 +0000
@@ -597,9 +597,10 @@
                                          1000000000ul, 32);
             hpet_events[i].shift = 32;
             hpet_events[i].next_event = STIME_MAX;
-            hpet_events[i].event_handler = handle_hpet_broadcast;
             spin_lock_init(&hpet_events[i].lock);
             rwlock_init(&hpet_events[i].cpumask_lock);
+            wmb();
+            hpet_events[i].event_handler = handle_hpet_broadcast;
         }
 
         return;
@@ -630,11 +631,12 @@
     legacy_hpet_event.mult = div_sc((unsigned long)hpet_rate, 1000000000ul, 
32);
     legacy_hpet_event.shift = 32;
     legacy_hpet_event.next_event = STIME_MAX;
-    legacy_hpet_event.event_handler = handle_hpet_broadcast;
     legacy_hpet_event.idx = 0;
     legacy_hpet_event.flags = 0;
     spin_lock_init(&legacy_hpet_event.lock);
     rwlock_init(&legacy_hpet_event.cpumask_lock);
+    wmb();
+    legacy_hpet_event.event_handler = handle_hpet_broadcast;
 
     if ( !force_hpet_broadcast )
         pv_rtc_handler = handle_rtc_once;

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