Integrate litmus_tick() in task_tick_litmus()

- remove the call to litmus_tick() from scheduler_tick() just after
  having performed the class task_tick() and integrate
  litmus_tick() in task_tick_litmus()

- task_tick_litmus() is the handler for the litmus class task_tick()
  method. It is called in non-queued mode from scheduler_tick()

1 files changed, 16 insertions, 16 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index ee894ee8a0bb..9ad41979c0b2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -485,6 +485,11 @@ struct rt_rq {
 #endif
 };
 
+/* Litmus related fields in a runqueue */
+struct litmus_rq {
+        struct task_struct *prev;
+};
+
 #ifdef CONFIG_SMP
 
 /*
@@ -549,6 +554,7 @@ struct rq {
 
         struct cfs_rq cfs;
         struct rt_rq rt;
+        struct litmus_rq litmus;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
         /* list of leaf cfs_rq on this cpu: */
@@ -574,8 +580,6 @@ struct rq {
 
         atomic_t nr_iowait;
 
-        struct task_struct *litmus_next;
-
 #ifdef CONFIG_SMP
         struct root_domain *rd;
         struct sched_domain *sd;
@@ -2786,6 +2790,15 @@ static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
 {
         if (prev->sched_class->pre_schedule)
                 prev->sched_class->pre_schedule(rq, prev);
+
+        /* LITMUS^RT not very clean hack: we need to save the prev task
+         * as our scheduling decision rely on it (as we drop the rq lock
+         * something in prev can change...); there is no way to escape
+         * this ack apart from modifying pick_nex_task(rq, _prev_) or
+         * falling back on the previous solution of decoupling
+         * scheduling decisions
+         */
+        rq->litmus.prev = prev;
 }
 
 /* rq->lock is NOT held, but preemption is disabled */
@@ -5252,13 +5265,8 @@ void scheduler_tick(void)
         update_cpu_load(rq);
         curr->sched_class->task_tick(rq, curr, 0);
 
-        /*
-         * LITMUS_TODO: can we move litmus_tick inside task_tick
-         * or will deadlock ?
-         */
-        TS_PLUGIN_TICK_START;
+        /* litmus_tick may force current to resched */
         litmus_tick(rq, curr);
-        TS_PLUGIN_TICK_END;
 
         spin_unlock(&rq->lock);
 
@@ -5470,14 +5478,6 @@ need_resched_nonpreemptible:
         update_rq_clock(rq);
         clear_tsk_need_resched(prev);
 
-        /*
-         * LITMUS_TODO: can we integrate litmus_schedule in
-         * pick_next_task?
-         */
-        TS_PLUGIN_SCHED_START;
-        litmus_schedule(rq, prev);
-        TS_PLUGIN_SCHED_END;
-
         if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
                 if (unlikely(signal_pending_state(prev->state, prev)))
                         prev->state = TASK_RUNNING;