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Date:   Mon,  6 Nov 2023 19:34:56 +0000
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Subject: [PATCH v6 13/20] sched: Split out __sched() deactivate task logic
 into a helper
From:   John Stultz <jstultz@google.com>
To:     LKML <linux-kernel@vger.kernel.org>
Cc:     John Stultz <jstultz@google.com>,
        Joel Fernandes <joelaf@google.com>,
        Qais Yousef <qyousef@google.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Valentin Schneider <vschneid@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>,
        Zimuzo Ezeozue <zezeozue@google.com>,
        Youssef Esmat <youssefesmat@google.com>,
        Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        "Paul E . McKenney" <paulmck@kernel.org>, kernel-team@android.com
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Precedence: bulk

As we're going to re-use the deactivation logic,
split it into a helper.

Cc: Joel Fernandes <joelaf@google.com>
Cc: Qais Yousef <qyousef@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Zimuzo Ezeozue <zezeozue@google.com>
Cc: Youssef Esmat <youssefesmat@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: kernel-team@android.com
Signed-off-by: John Stultz <jstultz@google.com>
---
v6:
* Define function as static to avoid "no previous prototype"
  warnings as Reported-by: kernel test robot <lkp@intel.com>
---
 kernel/sched/core.c | 65 +++++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 29 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9931940ba474..1b38b34d3f64 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6575,6 +6575,41 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 # define SM_MASK_PREEMPT	SM_PREEMPT
 #endif
 
+static bool try_to_deactivate_task(struct rq *rq, struct task_struct *p, unsigned long state)
+{
+	if (signal_pending_state(state, p)) {
+		WRITE_ONCE(p->__state, TASK_RUNNING);
+	} else {
+		p->sched_contributes_to_load =
+			(state & TASK_UNINTERRUPTIBLE) &&
+			!(state & TASK_NOLOAD) &&
+			!(state & TASK_FROZEN);
+
+		if (p->sched_contributes_to_load)
+			rq->nr_uninterruptible++;
+
+		/*
+		 * __schedule()			ttwu()
+		 *   prev_state = prev->state;    if (p->on_rq && ...)
+		 *   if (prev_state)		    goto out;
+		 *     p->on_rq = 0;		  smp_acquire__after_ctrl_dep();
+		 *				  p->state = TASK_WAKING
+		 *
+		 * Where __schedule() and ttwu() have matching control dependencies.
+		 *
+		 * After this, schedule() must not care about p->state any more.
+		 */
+		deactivate_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
+
+		if (p->in_iowait) {
+			atomic_inc(&rq->nr_iowait);
+			delayacct_blkio_start();
+		}
+		return true;
+	}
+	return false;
+}
+
 /*
  * __schedule() is the main scheduler function.
  *
@@ -6665,35 +6700,7 @@ static void __sched notrace __schedule(unsigned int sched_mode)
 	 */
 	prev_state = READ_ONCE(prev->__state);
 	if (!(sched_mode & SM_MASK_PREEMPT) && prev_state) {
-		if (signal_pending_state(prev_state, prev)) {
-			WRITE_ONCE(prev->__state, TASK_RUNNING);
-		} else {
-			prev->sched_contributes_to_load =
-				(prev_state & TASK_UNINTERRUPTIBLE) &&
-				!(prev_state & TASK_NOLOAD) &&
-				!(prev_state & TASK_FROZEN);
-
-			if (prev->sched_contributes_to_load)
-				rq->nr_uninterruptible++;
-
-			/*
-			 * __schedule()			ttwu()
-			 *   prev_state = prev->state;    if (p->on_rq && ...)
-			 *   if (prev_state)		    goto out;
-			 *     p->on_rq = 0;		  smp_acquire__after_ctrl_dep();
-			 *				  p->state = TASK_WAKING
-			 *
-			 * Where __schedule() and ttwu() have matching control dependencies.
-			 *
-			 * After this, schedule() must not care about p->state any more.
-			 */
-			deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
-
-			if (prev->in_iowait) {
-				atomic_inc(&rq->nr_iowait);
-				delayacct_blkio_start();
-			}
-		}
+		try_to_deactivate_task(rq, prev, prev_state);
 		switch_count = &prev->nvcsw;
 	}
 
-- 
2.42.0.869.gea05f2083d-goog