rt_domain_t: add add_release_on()

This API addition allows the calling code to override
the release master for a given rt_domain_t object. This
is particularly useful if a job is supposed to migrate
to a particular CPU. This need arises for example in semi-
partitioned schedulers.

2 files changed, 49 insertions, 7 deletions

diff --git a/include/litmus/rt_domain.h b/include/litmus/rt_domain.h
index 59e6b54e9281..ac249292e866 100644
--- a/include/litmus/rt_domain.h
+++ b/include/litmus/rt_domain.h
@@ -143,12 +143,26 @@ static inline struct task_struct* take_ready(rt_domain_t* rt)
 static inline void add_release(rt_domain_t* rt, struct task_struct *task)
 {
         unsigned long flags;
-        /* first we need the write lock for rt_ready_queue */
         raw_spin_lock_irqsave(&rt->tobe_lock, flags);
         __add_release(rt, task);
         raw_spin_unlock_irqrestore(&rt->tobe_lock, flags);
 }
 
+#ifdef CONFIG_RELEASE_MASTER
+void __add_release_on(rt_domain_t* rt, struct task_struct *task,
+                      int target_cpu);
+
+static inline void add_release_on(rt_domain_t* rt,
+                                  struct task_struct *task,
+                                  int target_cpu)
+{
+        unsigned long flags;
+        raw_spin_lock_irqsave(&rt->tobe_lock, flags);
+        __add_release_on(rt, task, target_cpu);
+        raw_spin_unlock_irqrestore(&rt->tobe_lock, flags);
+}
+#endif
+
 static inline int __jobs_pending(rt_domain_t* rt)
 {
         return !bheap_empty(&rt->ready_queue);
diff --git a/litmus/rt_domain.c b/litmus/rt_domain.c
index 8a3ff706c208..d27af48e0298 100644
--- a/litmus/rt_domain.c
+++ b/litmus/rt_domain.c
@@ -169,7 +169,12 @@ static void reinit_release_heap(struct task_struct* t)
  * - tobe_lock taken
  * - IRQ disabled
  */
-static void arm_release_timer(rt_domain_t *_rt)
+#ifdef CONFIG_RELEASE_MASTER
+#define arm_release_timer(t) arm_release_timer_on((t), NO_CPU)
+static void arm_release_timer_on(rt_domain_t *_rt , int target_cpu)
+#else
+static void arm_release_master(rt_domain_t *_rt)
+#endif
 {
         rt_domain_t *rt = _rt;
         struct list_head list;
@@ -224,17 +229,21 @@ static void arm_release_timer(rt_domain_t *_rt)
                          * PINNED mode is ok on both local and remote CPU
                          */
 #ifdef CONFIG_RELEASE_MASTER
-                        if (rt->release_master == NO_CPU)
+                        if (rt->release_master == NO_CPU &&
+                            target_cpu == NO_CPU)
 #endif
                                 __hrtimer_start_range_ns(&rh->timer,
                                                 ns_to_ktime(rh->release_time),
                                                 0, HRTIMER_MODE_ABS_PINNED, 0);
 #ifdef CONFIG_RELEASE_MASTER
                         else
-                                hrtimer_start_on(rt->release_master,
-                                                &rh->info, &rh->timer,
-                                                ns_to_ktime(rh->release_time),
-                                                HRTIMER_MODE_ABS_PINNED);
+                                hrtimer_start_on(
+                                        /* target_cpu overrides release master */
+                                        (target_cpu != NO_CPU ?
+                                         target_cpu : rt->release_master),
+                                        &rh->info, &rh->timer,
+                                        ns_to_ktime(rh->release_time),
+                                        HRTIMER_MODE_ABS_PINNED);
 #endif
                 } else
                         TRACE_TASK(t, "0x%p is not my timer\n", &rh->timer);
@@ -299,6 +308,25 @@ void __merge_ready(rt_domain_t* rt, struct bheap* tasks)
         rt->check_resched(rt);
 }
 
+
+#ifdef CONFIG_RELEASE_MASTER
+void __add_release_on(rt_domain_t* rt, struct task_struct *task,
+                      int target_cpu)
+{
+        TRACE_TASK(task, "add_release_on(), rel=%llu, target=%d\n",
+                   get_release(task), target_cpu);
+        list_add(&tsk_rt(task)->list, &rt->tobe_released);
+        task->rt_param.domain = rt;
+
+        /* start release timer */
+        TS_SCHED2_START(task);
+
+        arm_release_timer_on(rt, target_cpu);
+
+        TS_SCHED2_END(task);
+}
+#endif
+
 /* add_release - add a real-time task to the rt release queue.
  * @task:        the sleeping task
  */