scheduler: Introduce pcpu_schedule_lock

Many places in Xen, particularly schedule.c, grab the per-cpu spinlock
directly, rather than through vcpu_schedule_lock().  Since the lock
pointer may change between the time it's read and the time the lock is
successfully acquired, we need to check after acquiring the lock to
make sure that the pcpu's lock hasn't changed, due to cpu
initialization or cpupool activity.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index aad47706a9..bfe20d30d0 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -905,7 +905,7 @@ csched_runq_sort(struct csched_private *prv, unsigned int cpu)
 
     spc->runq_sort_last = sort_epoch;
 
-    spin_lock_irqsave(per_cpu(schedule_data, cpu).schedule_lock, flags);
+    pcpu_schedule_lock_irqsave(cpu, flags);
 
     runq = &spc->runq;
     elem = runq->next;
@@ -930,7 +930,7 @@ csched_runq_sort(struct csched_private *prv, unsigned int cpu)
         elem = next;
     }
 
-    spin_unlock_irqrestore(per_cpu(schedule_data, cpu).schedule_lock, flags);
+    pcpu_schedule_unlock_irqrestore(cpu, flags);
 }
 
 static void
@@ -1259,7 +1259,7 @@ csched_load_balance(struct csched_private *prv, int cpu,
          * cause a deadlock if the peer CPU is also load balancing and trying
          * to lock this CPU.
          */
-        if ( !spin_trylock(per_cpu(schedule_data, peer_cpu).schedule_lock) )
+        if ( !pcpu_schedule_trylock(peer_cpu) )
         {
             CSCHED_STAT_CRANK(steal_trylock_failed);
             continue;
@@ -1269,7 +1269,7 @@ csched_load_balance(struct csched_private *prv, int cpu,
          * Any work over there to steal?
          */
         speer = csched_runq_steal(peer_cpu, cpu, snext->pri);
-        spin_unlock(per_cpu(schedule_data, peer_cpu).schedule_lock);
+        pcpu_schedule_unlock(peer_cpu);
         if ( speer != NULL )
         {
             *stolen = 1;