[PATCH v7 10/23] sched: Split out __sched() deactivate task logic into a helper

John Stultz
2023-12-20T00:19:21Z

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: Metin Kaya <Metin.Kaya@arm.com>
Cc: Xuewen Yan <xuewen.yan94@gmail.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
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>
v7:
* Rename state task_state to be more clear, as suggested by
Metin Kaya
---
kernel/sched/core.c | 66 +++++++++++++++++++++++++--------------------
1 file changed, 37 insertions(+), 29 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0ce34f5c0e0c..34acd80b6bd0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6571,6 +6571,42 @@ 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 task_state)
+{
+ if (signal_pending_state(task_state, p)) {
+ WRITE_ONCE(p->__state, TASK_RUNNING);
+ } else {
+ p->sched_contributes_to_load =
+ (task_state & TASK_UNINTERRUPTIBLE) &&
+ !(task_state & TASK_NOLOAD) &&
+ !(task_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.
*
@@ -6662,35 +6698,7 @@ 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;
}

--
2.43.0.472.g3155946c3a-goog