sched/core: Simplify sched_class::pick_next_task()

Now that the indirect class call never uses the last two arguments of
pick_next_task(), remove them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: ktkhai@virtuozzo.com
Cc: mgorman@suse.de
Cc: qais.yousef@arm.com
Cc: qperret@google.com
Cc: rostedt@goodmis.org
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20191108131909.660595546@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7cf65474fa26b4c367e50e13ef78ecf146742e96..513a4794ff3644289d4b9d429907829a6adefc43 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3924,7 +3924,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
                /* Assumes fair_sched_class->next == idle_sched_class */
                if (!p) {
                        put_prev_task(rq, prev);
-                       p = pick_next_task_idle(rq, NULL, NULL);
+                       p = pick_next_task_idle(rq);
                }
 
                return p;
@@ -3949,7 +3949,7 @@ restart:
        put_prev_task(rq, prev);
 
        for_each_class(class) {
-               p = class->pick_next_task(rq, NULL, NULL);
+               p = class->pick_next_task(rq);
                if (p)
                        return p;
        }
@@ -6210,7 +6210,7 @@ static struct task_struct *__pick_migrate_task(struct rq *rq)
        struct task_struct *next;
 
        for_each_class(class) {
-               next = class->pick_next_task(rq, NULL, NULL);
+               next = class->pick_next_task(rq);
                if (next) {
                        next->sched_class->put_prev_task(rq, next);
                        return next;

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index a8a08030a8f7482e53c0fcdb19a13feb17440c7b..f7fbb44279594205d935a7d73768166667c11ea1 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1770,15 +1770,12 @@ static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
        return rb_entry(left, struct sched_dl_entity, rb_node);
 }
 
-static struct task_struct *
-pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+static struct task_struct *pick_next_task_dl(struct rq *rq)
 {
        struct sched_dl_entity *dl_se;
        struct dl_rq *dl_rq = &rq->dl;
        struct task_struct *p;
 
-       WARN_ON_ONCE(prev || rf);
-
        if (!sched_dl_runnable(rq))
                return NULL;
 

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index da81451d5575155895cf8114c202eb2849f22ae7..1789193d9917552d992de9ce05d29a754ed7c1d2 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6755,6 +6755,11 @@ idle:
        return NULL;
 }
 
+static struct task_struct *__pick_next_task_fair(struct rq *rq)
+{
+       return pick_next_task_fair(rq, NULL, NULL);
+}
+
 /*
  * Account for a descheduled task:
  */
@@ -10622,7 +10627,7 @@ const struct sched_class fair_sched_class = {
 
        .check_preempt_curr     = check_preempt_wakeup,
 
-       .pick_next_task         = pick_next_task_fair,
+       .pick_next_task         = __pick_next_task_fair,
        .put_prev_task          = put_prev_task_fair,
        .set_next_task          = set_next_task_fair,
 

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 0fdceac00b7009b6110fd20ef410960b97c5e64b..f88b79eeee1ece8e845854c5e1c00b214e93698f 100644 (file)
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -391,13 +391,10 @@ static void set_next_task_idle(struct rq *rq, struct task_struct *next)
        schedstat_inc(rq->sched_goidle);
 }
 
-struct task_struct *
-pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+struct task_struct *pick_next_task_idle(struct rq *rq)
 {
        struct task_struct *next = rq->idle;
 
-       WARN_ON_ONCE(prev || rf);
-
        set_next_task_idle(rq, next);
 
        return next;

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 9b8adc01be3da83e153a45713e4dc362412d277a..38027c04b04c26670fdf7a26a63f7b484f30b454 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1564,13 +1564,10 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq)
        return rt_task_of(rt_se);
 }
 
-static struct task_struct *
-pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+static struct task_struct *pick_next_task_rt(struct rq *rq)
 {
        struct task_struct *p;
 
-       WARN_ON_ONCE(prev || rf);
-
        if (!sched_rt_runnable(rq))
                return NULL;
 

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 66172a33767514e4d1bfe96c2de45e00ddddff33..75d96cce149260cd80dab6c212533a1a916d1f80 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1713,20 +1713,8 @@ struct sched_class {
 
        void (*check_preempt_curr)(struct rq *rq, struct task_struct *p, int flags);
 
-       /*
-        * Both @prev and @rf are optional and may be NULL, in which case the
-        * caller must already have invoked put_prev_task(rq, prev, rf).
-        *
-        * Otherwise it is the responsibility of the pick_next_task() to call
-        * put_prev_task() on the @prev task or something equivalent, IFF it
-        * returns a next task.
-        *
-        * In that case (@rf != NULL) it may return RETRY_TASK when it finds a
-        * higher prio class has runnable tasks.
-        */
-       struct task_struct * (*pick_next_task)(struct rq *rq,
-                                              struct task_struct *prev,
-                                              struct rq_flags *rf);
+       struct task_struct *(*pick_next_task)(struct rq *rq);
+
        void (*put_prev_task)(struct rq *rq, struct task_struct *p);
        void (*set_next_task)(struct rq *rq, struct task_struct *p);
 
@@ -1822,7 +1810,7 @@ static inline bool sched_fair_runnable(struct rq *rq)
 }
 
 extern struct task_struct *pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf);
-extern struct task_struct *pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf);
+extern struct task_struct *pick_next_task_idle(struct rq *rq);
 
 #ifdef CONFIG_SMP
 

diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index c0640739e05ee8f07318920cd3132ef18427f3bc..0aefdfb79b361c5b5d85a0f36430a03034a1b8fb 100644 (file)
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -34,11 +34,8 @@ static void set_next_task_stop(struct rq *rq, struct task_struct *stop)
        stop->se.exec_start = rq_clock_task(rq);
 }
 
-static struct task_struct *
-pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+static struct task_struct *pick_next_task_stop(struct rq *rq)
 {
-       WARN_ON_ONCE(prev || rf);
-
        if (!sched_stop_runnable(rq))
                return NULL;