sched: NULL pointer dereference while setting sched_rt_period_us

[linux-2.6] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index bfb8ad8ed1717bf95f82ddf7ea8b5b40bb7fbe7b..320e9a43d4cc0b34dbb846a110835c2d542c457d 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -312,12 +312,15 @@ static DEFINE_SPINLOCK(task_group_lock);
 #endif
 
 /*
- * A weight of 0, 1 or ULONG_MAX can cause arithmetics problems.
+ * A weight of 0 or 1 can cause arithmetics problems.
+ * A weight of a cfs_rq is the sum of weights of which entities
+ * are queued on this cfs_rq, so a weight of a entity should not be
+ * too large, so as the shares value of a task group.
  * (The default weight is 1024 - so there's no practical
  *  limitation from this.)
  */
 #define MIN_SHARES     2
-#define MAX_SHARES     (ULONG_MAX - 1)
+#define MAX_SHARES     (1UL << 18)
 
 static int init_task_group_load = INIT_TASK_GROUP_LOAD;
 #endif
@@ -1124,6 +1127,7 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer)
        return HRTIMER_NORESTART;
 }
 
+#ifdef CONFIG_SMP
 static void hotplug_hrtick_disable(int cpu)
 {
        struct rq *rq = cpu_rq(cpu);
@@ -1179,6 +1183,7 @@ static void init_hrtick(void)
 {
        hotcpu_notifier(hotplug_hrtick, 0);
 }
+#endif /* CONFIG_SMP */
 
 static void init_rq_hrtick(struct rq *rq)
 {
@@ -1337,8 +1342,13 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight,
 {
        u64 tmp;
 
-       if (!lw->inv_weight)
-               lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)/(lw->weight+1);
+       if (!lw->inv_weight) {
+               if (BITS_PER_LONG > 32 && unlikely(lw->weight >= WMULT_CONST))
+                       lw->inv_weight = 1;
+               else
+                       lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)
+                               / (lw->weight+1);
+       }
 
        tmp = (u64)delta_exec * weight;
        /*
@@ -4159,12 +4169,10 @@ need_resched_nonpreemptible:
        clear_tsk_need_resched(prev);
 
        if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
-               if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
-                               signal_pending(prev))) {
+               if (unlikely(signal_pending_state(prev->state, prev)))
                        prev->state = TASK_RUNNING;
-               } else {
+               else
                        deactivate_task(rq, prev, 1);
-               }
                switch_count = &prev->nvcsw;
        }
 
@@ -8342,7 +8350,7 @@ static unsigned long to_ratio(u64 period, u64 runtime)
 #ifdef CONFIG_CGROUP_SCHED
 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
 {
-       struct task_group *tgi, *parent = tg->parent;
+       struct task_group *tgi, *parent = tg ? tg->parent : NULL;
        unsigned long total = 0;
 
        if (!parent) {