sched/deadline: Add dl_task_is_earliest_deadline helper

Wrap repeated code in helper function dl_task_is_earliest_deadline, which
return true if there is no deadline task on the rq at all, or task's
deadline earlier than the whole rq.

Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Link: https://lore.kernel.org/r/20220826083453.698-1-shangxiaojing@huawei.com

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index d116d2b9d2f931bcf8f0cee26f5e0d8d49833433..34271aff471260dda9ac16cbfa9845f886e3a4ec 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1810,6 +1810,14 @@ static void yield_task_dl(struct rq *rq)
 
 #ifdef CONFIG_SMP
 
+static inline bool dl_task_is_earliest_deadline(struct task_struct *p,
+                                                struct rq *rq)
+{
+       return (!rq->dl.dl_nr_running ||
+               dl_time_before(p->dl.deadline,
+                              rq->dl.earliest_dl.curr));
+}
+
 static int find_later_rq(struct task_struct *task);
 
 static int
@@ -1852,9 +1860,7 @@ select_task_rq_dl(struct task_struct *p, int cpu, int flags)
                int target = find_later_rq(p);
 
                if (target != -1 &&
-                               (dl_time_before(p->dl.deadline,
-                                       cpu_rq(target)->dl.earliest_dl.curr) ||
-                               (cpu_rq(target)->dl.dl_nr_running == 0)))
+                   dl_task_is_earliest_deadline(p, cpu_rq(target)))
                        cpu = target;
        }
        rcu_read_unlock();
@@ -2221,9 +2227,7 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
 
                later_rq = cpu_rq(cpu);
 
-               if (later_rq->dl.dl_nr_running &&
-                   !dl_time_before(task->dl.deadline,
-                                       later_rq->dl.earliest_dl.curr)) {
+               if (!dl_task_is_earliest_deadline(task, later_rq)) {
                        /*
                         * Target rq has tasks of equal or earlier deadline,
                         * retrying does not release any lock and is unlikely
@@ -2251,9 +2255,7 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
                 * its earliest one has a later deadline than our
                 * task, the rq is a good one.
                 */
-               if (!later_rq->dl.dl_nr_running ||
-                   dl_time_before(task->dl.deadline,
-                                  later_rq->dl.earliest_dl.curr))
+               if (dl_task_is_earliest_deadline(task, later_rq))
                        break;
 
                /* Otherwise we try again. */
@@ -2424,9 +2426,7 @@ static void pull_dl_task(struct rq *this_rq)
                 *  - it will preempt the last one we pulled (if any).
                 */
                if (p && dl_time_before(p->dl.deadline, dmin) &&
-                   (!this_rq->dl.dl_nr_running ||
-                    dl_time_before(p->dl.deadline,
-                                   this_rq->dl.earliest_dl.curr))) {
+                   dl_task_is_earliest_deadline(p, this_rq)) {
                        WARN_ON(p == src_rq->curr);
                        WARN_ON(!task_on_rq_queued(p));