[Xen-changelog] [xen-4.1-testing] xen: Fix schedule()'s grabbing of the schedule lock

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User George Dunlap <george.dunlap@xxxxxxxxxxxxx>
# Date 1341825884 -3600
# Node ID c1f43d07dc1ed4203afe4f0a207da04213c53e3e
# Parent  01366a3245870bed6666f98d498528697d082701
xen: Fix schedule()'s grabbing of the schedule lock

Because the location of the lock can change between the time you read
it and the time you grab it, the per-cpu schedule locks need to check
after lock acquisition that the lock location hasn't changed, and
release and re-try if so.  This change was effected throughout the
source code, but one very important place was apparently missed: in
schedule() itself.

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Committed-by: Keir Fraser <keir@xxxxxxx>
xen-unstable changeset:   25162:478bec603d3d
xen-unstable date:        Tue Apr 10 10:41:30 2012 +0100
---


diff -r 01366a324587 -r c1f43d07dc1e xen/common/schedule.c
--- a/xen/common/schedule.c     Mon Jul 09 10:23:57 2012 +0100
+++ b/xen/common/schedule.c     Mon Jul 09 10:24:44 2012 +0100
@@ -1122,6 +1122,7 @@ static void schedule(void)
     bool_t                tasklet_work_scheduled = 0;
     struct schedule_data *sd;
     struct task_slice     next_slice;
+    int cpu = smp_processor_id();
 
     ASSERT(!in_atomic());
 
@@ -1146,7 +1147,7 @@ static void schedule(void)
         BUG();
     }
 
-    spin_lock_irq(sd->schedule_lock);
+    pcpu_schedule_lock_irq(cpu);
 
     stop_timer(&sd->s_timer);
     
@@ -1163,7 +1164,7 @@ static void schedule(void)
 
     if ( unlikely(prev == next) )
     {
-        spin_unlock_irq(sd->schedule_lock);
+        pcpu_schedule_unlock_irq(cpu);
         trace_continue_running(next);
         return continue_running(prev);
     }
@@ -1201,7 +1202,7 @@ static void schedule(void)
     ASSERT(!next->is_running);
     next->is_running = 1;
 
-    spin_unlock_irq(sd->schedule_lock);
+    pcpu_schedule_unlock_irq(cpu);
 
     perfc_incr(sched_ctx);
 

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog