Merge branch 'for-2.6.34-incoming' into for-2.6.35-incoming

[pandora-kernel.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 6af210a..3c2a54f 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -323,6 +323,15 @@ static inline struct task_group *task_group(struct task_struct *p)
 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 {
+       /*
+        * Strictly speaking this rcu_read_lock() is not needed since the
+        * task_group is tied to the cgroup, which in turn can never go away
+        * as long as there are tasks attached to it.
+        *
+        * However since task_group() uses task_subsys_state() which is an
+        * rcu_dereference() user, this quiets CONFIG_PROVE_RCU.
+        */
+       rcu_read_lock();
 #ifdef CONFIG_FAIR_GROUP_SCHED
        p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
        p->se.parent = task_group(p)->se[cpu];
@@ -332,6 +341,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
        p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
        p->rt.parent = task_group(p)->rt_se[cpu];
 #endif
+       rcu_read_unlock();
 }
 
 #else
@@ -3780,7 +3790,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
         * the mutex owner just released it and exited.
         */
        if (probe_kernel_address(&owner->cpu, cpu))
-               goto out;
+               return 0;
 #else
        cpu = owner->cpu;
 #endif
@@ -3790,14 +3800,14 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
         * the cpu field may no longer be valid.
         */
        if (cpu >= nr_cpumask_bits)
-               goto out;
+               return 0;
 
        /*
         * We need to validate that we can do a
         * get_cpu() and that we have the percpu area.
         */
        if (!cpu_online(cpu))
-               goto out;
+               return 0;
 
        rq = cpu_rq(cpu);
 
@@ -3816,7 +3826,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
 
                cpu_relax();
        }
-out:
+
        return 1;
 }
 #endif