sched: Remove rq_iterator from move_one_task

Again, since we only iterate the fair class, remove the abstraction.

Since this is the last user of the rq_iterator, remove all that too.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 36 insertions, 110 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 709deb33708a..e48e459da98d 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1814,54 +1814,6 @@ static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
  * Fair scheduling class load-balancing methods:
  */
 
-/*
- * Load-balancing iterator. Note: while the runqueue stays locked
- * during the whole iteration, the current task might be
- * dequeued so the iterator has to be dequeue-safe. Here we
- * achieve that by always pre-iterating before returning
- * the current task:
- */
-static struct task_struct *
-__load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
-{
-        struct task_struct *p = NULL;
-        struct sched_entity *se;
-
-        if (next == &cfs_rq->tasks)
-                return NULL;
-
-        se = list_entry(next, struct sched_entity, group_node);
-        p = task_of(se);
-        cfs_rq->balance_iterator = next->next;
-
-        return p;
-}
-
-static struct task_struct *load_balance_start_fair(void *arg)
-{
-        struct cfs_rq *cfs_rq = arg;
-
-        return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
-}
-
-static struct task_struct *load_balance_next_fair(void *arg)
-{
-        struct cfs_rq *cfs_rq = arg;
-
-        return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
-}
-
-/*
- * runqueue iterator, to support SMP load-balancing between different
- * scheduling classes, without having to expose their internal data
- * structures to the load-balancing proper:
- */
-struct rq_iterator {
-        void *arg;
-        struct task_struct *(*start)(void *);
-        struct task_struct *(*next)(void *);
-};
-
 static unsigned long
 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
                 unsigned long max_load_move, struct sched_domain *sd,
@@ -1929,42 +1881,6 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
 }
 #endif
 
-static int
-iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
-                struct sched_domain *sd, enum cpu_idle_type idle,
-                struct rq_iterator *iterator);
-
-/*
- * move_one_task tries to move exactly one task from busiest to this_rq, as
- * part of active balancing operations within "domain".
- * Returns 1 if successful and 0 otherwise.
- *
- * Called with both runqueues locked.
- */
-static int
-move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
-              struct sched_domain *sd, enum cpu_idle_type idle)
-{
-        struct cfs_rq *busy_cfs_rq;
-        struct rq_iterator cfs_rq_iterator;
-
-        cfs_rq_iterator.start = load_balance_start_fair;
-        cfs_rq_iterator.next = load_balance_next_fair;
-
-        for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
-                /*
-                 * pass busy_cfs_rq argument into
-                 * load_balance_[start|next]_fair iterators
-                 */
-                cfs_rq_iterator.arg = busy_cfs_rq;
-                if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
-                                       &cfs_rq_iterator))
-                    return 1;
-        }
-
-        return 0;
-}
-
 /*
  * pull_task - move a task from a remote runqueue to the local runqueue.
  * Both runqueues must be locked.
@@ -2029,6 +1945,42 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
         return 1;
 }
 
+/*
+ * move_one_task tries to move exactly one task from busiest to this_rq, as
+ * part of active balancing operations within "domain".
+ * Returns 1 if successful and 0 otherwise.
+ *
+ * Called with both runqueues locked.
+ */
+static int
+move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
+              struct sched_domain *sd, enum cpu_idle_type idle)
+{
+        struct task_struct *p, *n;
+        struct cfs_rq *cfs_rq;
+        int pinned = 0;
+
+        for_each_leaf_cfs_rq(busiest, cfs_rq) {
+                list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
+
+                        if (!can_migrate_task(p, busiest, this_cpu,
+                                                sd, idle, &pinned))
+                                continue;
+
+                        pull_task(busiest, p, this_rq, this_cpu);
+                        /*
+                         * Right now, this is only the second place pull_task()
+                         * is called, so we can safely collect pull_task()
+                         * stats here rather than inside pull_task().
+                         */
+                        schedstat_inc(sd, lb_gained[idle]);
+                        return 1;
+                }
+        }
+
+        return 0;
+}
+
 static unsigned long
 balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
               unsigned long max_load_move, struct sched_domain *sd,
@@ -2126,32 +2078,6 @@ static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
         return total_load_moved > 0;
 }
 
-static int
-iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
-                   struct sched_domain *sd, enum cpu_idle_type idle,
-                   struct rq_iterator *iterator)
-{
-        struct task_struct *p = iterator->start(iterator->arg);
-        int pinned = 0;
-
-        while (p) {
-                if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
-                        pull_task(busiest, p, this_rq, this_cpu);
-                        /*
-                         * Right now, this is only the second place pull_task()
-                         * is called, so we can safely collect pull_task()
-                         * stats here rather than inside pull_task().
-                         */
-                        schedstat_inc(sd, lb_gained[idle]);
-
-                        return 1;
-                }
-                p = iterator->next(iterator->arg);
-        }
-
-        return 0;
-}
-
 /********** Helpers for find_busiest_group ************************/
 /*
  * sd_lb_stats - Structure to store the statistics of a sched_domain