# HG changeset patch
# User Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
# Date 1315910154 -7200
# Node ID 86f2a3a45ecbcc49aba88d06bf13bbcaf5a9b89b
# Parent  64aab9a077ea937b31fd678b02f755139b924184
Avoid race in schedule() when switching schedulers

Selecting the scheduler to call must be done under lock. Otherwise a race
might occur when switching schedulers in a cpupool

Signed-off-by: juergen.gross@xxxxxxxxxxxxxx

diff -r 64aab9a077ea -r 86f2a3a45ecb xen/common/schedule.c
--- a/xen/common/schedule.c	Tue Sep 13 11:20:57 2011 +0100
+++ b/xen/common/schedule.c	Tue Sep 13 12:35:54 2011 +0200
@@ -1107,7 +1107,7 @@ static void schedule(void)
 {
     struct vcpu          *prev = current, *next = NULL;
     s_time_t              now = NOW();
-    struct scheduler     *sched = this_cpu(scheduler);
+    struct scheduler     *sched;
     unsigned long        *tasklet_work = &this_cpu(tasklet_work_to_do);
     bool_t                tasklet_work_scheduled = 0;
     struct schedule_data *sd;
@@ -1141,6 +1141,7 @@ static void schedule(void)
     stop_timer(&sd->s_timer);
     
     /* get policy-specific decision on scheduling... */
+    sched = this_cpu(scheduler);
     next_slice = sched->do_schedule(sched, now, tasklet_work_scheduled);
 
     next = next_slice.task;