sched: Use an accessor to read the rq clock

Read the runqueue clock through an accessor. This
prepares for adding a debugging infrastructure to
detect missing or redundant calls to update_rq_clock()
between a scheduler's entry and exit point.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

6 files changed, 47 insertions, 37 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 46d00172ae4a..36f85be2932b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -667,7 +667,7 @@ void sched_avg_update(struct rq *rq)
 {
         s64 period = sched_avg_period();
 
-        while ((s64)(rq->clock - rq->age_stamp) > period) {
+        while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
                 /*
                  * Inline assembly required to prevent the compiler
                  * optimising this loop into a divmod call.
@@ -1328,7 +1328,7 @@ ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
                 p->sched_class->task_woken(rq, p);
 
         if (rq->idle_stamp) {
-                u64 delta = rq->clock - rq->idle_stamp;
+                u64 delta = rq_clock(rq) - rq->idle_stamp;
                 u64 max = 2*sysctl_sched_migration_cost;
 
                 if (delta > max)
@@ -2106,7 +2106,7 @@ static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
 
         if (task_current(rq, p)) {
                 update_rq_clock(rq);
-                ns = rq->clock_task - p->se.exec_start;
+                ns = rq_clock_task(rq) - p->se.exec_start;
                 if ((s64)ns < 0)
                         ns = 0;
         }
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1c8762a5370c..3ee1c2e4ae60 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -704,7 +704,7 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
 static void update_curr(struct cfs_rq *cfs_rq)
 {
         struct sched_entity *curr = cfs_rq->curr;
-        u64 now = rq_of(cfs_rq)->clock_task;
+        u64 now = rq_clock_task(rq_of(cfs_rq));
         unsigned long delta_exec;
 
         if (unlikely(!curr))
@@ -736,7 +736,7 @@ static void update_curr(struct cfs_rq *cfs_rq)
 static inline void
 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-        schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
+        schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq)));
 }
 
 /*
@@ -756,14 +756,14 @@ static void
 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
         schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
-                        rq_of(cfs_rq)->clock - se->statistics.wait_start));
+                        rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start));
         schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
         schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
-                        rq_of(cfs_rq)->clock - se->statistics.wait_start);
+                        rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start);
 #ifdef CONFIG_SCHEDSTATS
         if (entity_is_task(se)) {
                 trace_sched_stat_wait(task_of(se),
-                        rq_of(cfs_rq)->clock - se->statistics.wait_start);
+                        rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start);
         }
 #endif
         schedstat_set(se->statistics.wait_start, 0);
@@ -789,7 +789,7 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
         /*
          * We are starting a new run period:
          */
-        se->exec_start = rq_of(cfs_rq)->clock_task;
+        se->exec_start = rq_clock_task(rq_of(cfs_rq));
 }
 
 /**************************************************
@@ -1515,7 +1515,7 @@ static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
 
 static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
 {
-        __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
+        __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
         __update_tg_runnable_avg(&rq->avg, &rq->cfs);
 }
 
@@ -1530,7 +1530,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
          * accumulated while sleeping.
          */
         if (unlikely(se->avg.decay_count <= 0)) {
-                se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task;
+                se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq));
                 if (se->avg.decay_count) {
                         /*
                          * In a wake-up migration we have to approximate the
@@ -1625,7 +1625,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
                 tsk = task_of(se);
 
         if (se->statistics.sleep_start) {
-                u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
+                u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.sleep_start;
 
                 if ((s64)delta < 0)
                         delta = 0;
@@ -1642,7 +1642,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
                 }
         }
         if (se->statistics.block_start) {
-                u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
+                u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.block_start;
 
                 if ((s64)delta < 0)
                         delta = 0;
@@ -1823,9 +1823,9 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
                         struct task_struct *tsk = task_of(se);
 
                         if (tsk->state & TASK_INTERRUPTIBLE)
-                                se->statistics.sleep_start = rq_of(cfs_rq)->clock;
+                                se->statistics.sleep_start = rq_clock(rq_of(cfs_rq));
                         if (tsk->state & TASK_UNINTERRUPTIBLE)
-                                se->statistics.block_start = rq_of(cfs_rq)->clock;
+                                se->statistics.block_start = rq_clock(rq_of(cfs_rq));
                 }
 #endif
         }
@@ -2100,7 +2100,7 @@ static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
         if (unlikely(cfs_rq->throttle_count))
                 return cfs_rq->throttled_clock_task;
 
-        return rq_of(cfs_rq)->clock_task - cfs_rq->throttled_clock_task_time;
+        return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time;
 }
 
 /* returns 0 on failure to allocate runtime */
@@ -2159,7 +2159,7 @@ static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
         struct rq *rq = rq_of(cfs_rq);
 
         /* if the deadline is ahead of our clock, nothing to do */
-        if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
+        if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0))
                 return;
 
         if (cfs_rq->runtime_remaining < 0)
@@ -2248,7 +2248,7 @@ static int tg_unthrottle_up(struct task_group *tg, void *data)
 #ifdef CONFIG_SMP
         if (!cfs_rq->throttle_count) {
                 /* adjust cfs_rq_clock_task() */
-                cfs_rq->throttled_clock_task_time += rq->clock_task -
+                cfs_rq->throttled_clock_task_time += rq_clock_task(rq) -
                                              cfs_rq->throttled_clock_task;
         }
 #endif
@@ -2263,7 +2263,7 @@ static int tg_throttle_down(struct task_group *tg, void *data)
 
         /* group is entering throttled state, stop time */
         if (!cfs_rq->throttle_count)
-                cfs_rq->throttled_clock_task = rq->clock_task;
+                cfs_rq->throttled_clock_task = rq_clock_task(rq);
         cfs_rq->throttle_count++;
 
         return 0;
@@ -2302,7 +2302,7 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
                 rq->nr_running -= task_delta;
 
         cfs_rq->throttled = 1;
-        cfs_rq->throttled_clock = rq->clock;
+        cfs_rq->throttled_clock = rq_clock(rq);
         raw_spin_lock(&cfs_b->lock);
         list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
         raw_spin_unlock(&cfs_b->lock);
@@ -2323,7 +2323,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
         update_rq_clock(rq);
 
         raw_spin_lock(&cfs_b->lock);
-        cfs_b->throttled_time += rq->clock - cfs_rq->throttled_clock;
+        cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
         list_del_rcu(&cfs_rq->throttled_list);
         raw_spin_unlock(&cfs_b->lock);
 
@@ -2726,7 +2726,7 @@ static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
 #else /* CONFIG_CFS_BANDWIDTH */
 static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
 {
-        return rq_of(cfs_rq)->clock_task;
+        return rq_clock_task(rq_of(cfs_rq));
 }
 
 static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
@@ -3966,7 +3966,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
          * 2) too many balance attempts have failed.
          */
 
-        tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
+        tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq), env->sd);
         if (!tsk_cache_hot ||
                 env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
 
@@ -4322,7 +4322,7 @@ static unsigned long scale_rt_power(int cpu)
         age_stamp = ACCESS_ONCE(rq->age_stamp);
         avg = ACCESS_ONCE(rq->rt_avg);
 
-        total = sched_avg_period() + (rq->clock - age_stamp);
+        total = sched_avg_period() + (rq_clock(rq) - age_stamp);
 
         if (unlikely(total < avg)) {
                 /* Ensures that power won't end up being negative */
@@ -5261,7 +5261,7 @@ void idle_balance(int this_cpu, struct rq *this_rq)
         int pulled_task = 0;
         unsigned long next_balance = jiffies + HZ;
 
-        this_rq->idle_stamp = this_rq->clock;
+        this_rq->idle_stamp = rq_clock(this_rq);
 
         if (this_rq->avg_idle < sysctl_sched_migration_cost)
                 return;
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 8853ab17b750..8d85f9ac4262 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -886,7 +886,7 @@ static void update_curr_rt(struct rq *rq)
         if (curr->sched_class != &rt_sched_class)
                 return;
 
-        delta_exec = rq->clock_task - curr->se.exec_start;
+        delta_exec = rq_clock_task(rq) - curr->se.exec_start;
         if (unlikely((s64)delta_exec <= 0))
                 return;
 
@@ -896,7 +896,7 @@ static void update_curr_rt(struct rq *rq)
         curr->se.sum_exec_runtime += delta_exec;
         account_group_exec_runtime(curr, delta_exec);
 
-        curr->se.exec_start = rq->clock_task;
+        curr->se.exec_start = rq_clock_task(rq);
         cpuacct_charge(curr, delta_exec);
 
         sched_rt_avg_update(rq, delta_exec);
@@ -1345,7 +1345,7 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq)
         } while (rt_rq);
 
         p = rt_task_of(rt_se);
-        p->se.exec_start = rq->clock_task;
+        p->se.exec_start = rq_clock_task(rq);
 
         return p;
 }
@@ -1997,7 +1997,7 @@ static void set_curr_task_rt(struct rq *rq)
 {
         struct task_struct *p = rq->curr;
 
-        p->se.exec_start = rq->clock_task;
+        p->se.exec_start = rq_clock_task(rq);
 
         /* The running task is never eligible for pushing */
         dequeue_pushable_task(rq, p);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c806c61a1261..74ff659e964f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -548,6 +548,16 @@ DECLARE_PER_CPU(struct rq, runqueues);
 #define cpu_curr(cpu)           (cpu_rq(cpu)->curr)
 #define raw_rq()                (&__raw_get_cpu_var(runqueues))
 
+static inline u64 rq_clock(struct rq *rq)
+{
+        return rq->clock;
+}
+
+static inline u64 rq_clock_task(struct rq *rq)
+{
+        return rq->clock_task;
+}
+
 #ifdef CONFIG_SMP
 
 #define rcu_dereference_check_sched_domain(p) \
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 2ef90a51ec5e..17d7065c3872 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -61,7 +61,7 @@ static inline void sched_info_reset_dequeued(struct task_struct *t)
  */
 static inline void sched_info_dequeued(struct task_struct *t)
 {
-        unsigned long long now = task_rq(t)->clock, delta = 0;
+        unsigned long long now = rq_clock(task_rq(t)), delta = 0;
 
         if (unlikely(sched_info_on()))
                 if (t->sched_info.last_queued)
@@ -79,7 +79,7 @@ static inline void sched_info_dequeued(struct task_struct *t)
  */
 static void sched_info_arrive(struct task_struct *t)
 {
-        unsigned long long now = task_rq(t)->clock, delta = 0;
+        unsigned long long now = rq_clock(task_rq(t)), delta = 0;
 
         if (t->sched_info.last_queued)
                 delta = now - t->sched_info.last_queued;
@@ -100,7 +100,7 @@ static inline void sched_info_queued(struct task_struct *t)
 {
         if (unlikely(sched_info_on()))
                 if (!t->sched_info.last_queued)
-                        t->sched_info.last_queued = task_rq(t)->clock;
+                        t->sched_info.last_queued = rq_clock(task_rq(t));
 }
 
 /*
@@ -112,7 +112,7 @@ static inline void sched_info_queued(struct task_struct *t)
  */
 static inline void sched_info_depart(struct task_struct *t)
 {
-        unsigned long long delta = task_rq(t)->clock -
+        unsigned long long delta = rq_clock(task_rq(t)) -
                                         t->sched_info.last_arrival;
 
         rq_sched_info_depart(task_rq(t), delta);
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index da5eb5bed84a..e08fbeeb54b9 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -28,7 +28,7 @@ static struct task_struct *pick_next_task_stop(struct rq *rq)
         struct task_struct *stop = rq->stop;
 
         if (stop && stop->on_rq) {
-                stop->se.exec_start = rq->clock_task;
+                stop->se.exec_start = rq_clock_task(rq);
                 return stop;
         }
 
@@ -57,7 +57,7 @@ static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
         struct task_struct *curr = rq->curr;
         u64 delta_exec;
 
-        delta_exec = rq->clock_task - curr->se.exec_start;
+        delta_exec = rq_clock_task(rq) - curr->se.exec_start;
         if (unlikely((s64)delta_exec < 0))
                 delta_exec = 0;
 
@@ -67,7 +67,7 @@ static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
         curr->se.sum_exec_runtime += delta_exec;
         account_group_exec_runtime(curr, delta_exec);
 
-        curr->se.exec_start = rq->clock_task;
+        curr->se.exec_start = rq_clock_task(rq);
         cpuacct_charge(curr, delta_exec);
 }
 
@@ -79,7 +79,7 @@ static void set_curr_task_stop(struct rq *rq)
 {
         struct task_struct *stop = rq->stop;
 
-        stop->se.exec_start = rq->clock_task;
+        stop->se.exec_start = rq_clock_task(rq);
 }
 
 static void switched_to_stop(struct rq *rq, struct task_struct *p)