[RFC PATCH 38/86] sched: *_tsk_need_resched() now takes resched_t

[Ankur Arora <ankur.a.arora@oracle.com>]

*_tsk_need_resched() need to test for the specific need-resched
flag.

The only users are RCU and the scheduler. For RCU we always want
to schedule at the earliest opportunity and that is always
RESCHED_eager.

For the scheduler, keep everything as RESCHED_eager for now.

Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 include/linux/sched.h    | 17 ++++++++++++-----
 kernel/rcu/tree.c        |  4 ++--
 kernel/rcu/tree_exp.h    |  4 ++--
 kernel/rcu/tree_plugin.h |  4 ++--
 kernel/rcu/tree_stall.h  |  2 +-
 kernel/sched/core.c      |  9 +++++----
 kernel/sched/deadline.c  |  4 ++--
 kernel/sched/fair.c      |  2 +-
 kernel/sched/idle.c      |  2 +-
 kernel/sched/rt.c        |  4 ++--
 10 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 12d0626601a0..6dd206b2ef50 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2060,19 +2060,26 @@ static inline bool test_tsk_thread_flag(struct task_struct *tsk, int flag)
 	return test_ti_thread_flag(task_thread_info(tsk), flag);
 }
 
-static inline void set_tsk_need_resched(struct task_struct *tsk)
+static inline void set_tsk_need_resched(struct task_struct *tsk, resched_t lazy)
 {
-	set_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
+	set_tsk_thread_flag(tsk, tif_resched(lazy));
 }
 
 static inline void clear_tsk_need_resched(struct task_struct *tsk)
 {
-	clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
+	clear_tsk_thread_flag(tsk, tif_resched(RESCHED_eager));
+	clear_tsk_thread_flag(tsk, tif_resched(RESCHED_lazy));
 }
 
-static inline bool test_tsk_need_resched(struct task_struct *tsk)
+static inline bool test_tsk_need_resched(struct task_struct *tsk, resched_t lazy)
 {
-	return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
+	return unlikely(test_tsk_thread_flag(tsk, tif_resched(lazy)));
+}
+
+static inline bool test_tsk_need_resched_any(struct task_struct *tsk)
+{
+	return test_tsk_need_resched(tsk, RESCHED_eager) ||
+			test_tsk_need_resched(tsk, RESCHED_lazy);
 }
 
 /*
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index cb1caefa8bd0..a7776ae78900 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2231,7 +2231,7 @@ void rcu_sched_clock_irq(int user)
 	if (smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) {
 		/* Idle and userspace execution already are quiescent states. */
 		if (!rcu_is_cpu_rrupt_from_idle() && !user) {
-			set_tsk_need_resched(current);
+			set_tsk_need_resched(current, RESCHED_eager);
 			set_preempt_need_resched();
 		}
 		__this_cpu_write(rcu_data.rcu_urgent_qs, false);
@@ -2379,7 +2379,7 @@ static __latent_entropy void rcu_core(void)
 	if (IS_ENABLED(CONFIG_PREEMPT_COUNT) && (!(preempt_count() & PREEMPT_MASK))) {
 		rcu_preempt_deferred_qs(current);
 	} else if (rcu_preempt_need_deferred_qs(current)) {
-		set_tsk_need_resched(current);
+		set_tsk_need_resched(current, RESCHED_eager);
 		set_preempt_need_resched();
 	}
 
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 8239b39d945b..a4a23ac1115b 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -755,7 +755,7 @@ static void rcu_exp_handler(void *unused)
 			rcu_report_exp_rdp(rdp);
 		} else {
 			WRITE_ONCE(rdp->cpu_no_qs.b.exp, true);
-			set_tsk_need_resched(t);
+			set_tsk_need_resched(t, RESCHED_eager);
 			set_preempt_need_resched();
 		}
 		return;
@@ -856,7 +856,7 @@ static void rcu_exp_need_qs(void)
 	__this_cpu_write(rcu_data.cpu_no_qs.b.exp, true);
 	/* Store .exp before .rcu_urgent_qs. */
 	smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true);
-	set_tsk_need_resched(current);
+	set_tsk_need_resched(current, RESCHED_eager);
 	set_preempt_need_resched();
 }
 
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 41021080ad25..f87191e008ff 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -658,7 +658,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
 			// Also if no expediting and no possible deboosting,
 			// slow is OK.  Plus nohz_full CPUs eventually get
 			// tick enabled.
-			set_tsk_need_resched(current);
+			set_tsk_need_resched(current, RESCHED_eager);
 			set_preempt_need_resched();
 			if (IS_ENABLED(CONFIG_IRQ_WORK) && irqs_were_disabled &&
 			    expboost && !rdp->defer_qs_iw_pending && cpu_online(rdp->cpu)) {
@@ -725,7 +725,7 @@ static void rcu_flavor_sched_clock_irq(int user)
 	    (preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK))) {
 		/* No QS, force context switch if deferred. */
 		if (rcu_preempt_need_deferred_qs(t)) {
-			set_tsk_need_resched(t);
+			set_tsk_need_resched(t, RESCHED_eager);
 			set_preempt_need_resched();
 		}
 	} else if (rcu_preempt_need_deferred_qs(t)) {
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 6f06dc12904a..b74b7b04cf35 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -705,7 +705,7 @@ static void print_cpu_stall(unsigned long gps)
 	 * progress and it could be we're stuck in kernel space without context
 	 * switches for an entirely unreasonable amount of time.
 	 */
-	set_tsk_need_resched(current);
+	set_tsk_need_resched(current, RESCHED_eager);
 	set_preempt_need_resched();
 }
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e30007c11722..e2215c417323 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -927,7 +927,7 @@ static bool set_nr_if_polling(struct task_struct *p)
 #else
 static inline bool set_nr_and_not_polling(struct task_struct *p)
 {
-	set_tsk_need_resched(p);
+	set_tsk_need_resched(p, RESCHED_eager);
 	return true;
 }
 
@@ -1039,13 +1039,13 @@ void resched_curr(struct rq *rq)
 
 	lockdep_assert_rq_held(rq);
 
-	if (test_tsk_need_resched(curr))
+	if (test_tsk_need_resched(curr, RESCHED_eager))
 		return;
 
 	cpu = cpu_of(rq);
 
 	if (cpu == smp_processor_id()) {
-		set_tsk_need_resched(curr);
+		set_tsk_need_resched(curr, RESCHED_eager);
 		set_preempt_need_resched();
 		return;
 	}
@@ -2223,7 +2223,8 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
 	 * A queue event has occurred, and we're going to schedule.  In
 	 * this case, we can save a useless back to back clock update.
 	 */
-	if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
+	if (task_on_rq_queued(rq->curr) &&
+	    test_tsk_need_resched(rq->curr, RESCHED_eager))
 		rq_clock_skip_update(rq);
 }
 
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 58b542bf2893..e6815c3bd2f0 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1953,7 +1953,7 @@ static void check_preempt_curr_dl(struct rq *rq, struct task_struct *p,
 	 * let us try to decide what's the best thing to do...
 	 */
 	if ((p->dl.deadline == rq->curr->dl.deadline) &&
-	    !test_tsk_need_resched(rq->curr))
+	    !test_tsk_need_resched(rq->curr, RESCHED_eager))
 		check_preempt_equal_dl(rq, p);
 #endif /* CONFIG_SMP */
 }
@@ -2467,7 +2467,7 @@ static void pull_dl_task(struct rq *this_rq)
 static void task_woken_dl(struct rq *rq, struct task_struct *p)
 {
 	if (!task_on_cpu(rq, p) &&
-	    !test_tsk_need_resched(rq->curr) &&
+	    !test_tsk_need_resched(rq->curr, RESCHED_eager) &&
 	    p->nr_cpus_allowed > 1 &&
 	    dl_task(rq->curr) &&
 	    (rq->curr->nr_cpus_allowed < 2 ||
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index df348aa55d3c..4d86c618ffa2 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8087,7 +8087,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
 	 * prevents us from potentially nominating it as a false LAST_BUDDY
 	 * below.
 	 */
-	if (test_tsk_need_resched(curr))
+	if (test_tsk_need_resched(curr, RESCHED_eager))
 		return;
 
 	/* Idle tasks are by definition preempted by non-idle tasks. */
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index d4a55448e459..eacd204e2879 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -329,7 +329,7 @@ static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer)
 	struct idle_timer *it = container_of(timer, struct idle_timer, timer);
 
 	WRITE_ONCE(it->done, 1);
-	set_tsk_need_resched(current);
+	set_tsk_need_resched(current, RESCHED_eager);
 
 	return HRTIMER_NORESTART;
 }
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 0597ba0f85ff..a79ce6746dd0 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1735,7 +1735,7 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flag
 	 * to move current somewhere else, making room for our non-migratable
 	 * task.
 	 */
-	if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
+	if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr, RESCHED_eager))
 		check_preempt_equal_prio(rq, p);
 #endif
 }
@@ -2466,7 +2466,7 @@ static void pull_rt_task(struct rq *this_rq)
 static void task_woken_rt(struct rq *rq, struct task_struct *p)
 {
 	bool need_to_push = !task_on_cpu(rq, p) &&
-			    !test_tsk_need_resched(rq->curr) &&
+			    !test_tsk_need_resched(rq->curr, RESCHED_eager) &&
 			    p->nr_cpus_allowed > 1 &&
 			    (dl_task(rq->curr) || rt_task(rq->curr)) &&
 			    (rq->curr->nr_cpus_allowed < 2 ||
-- 
2.31.1