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sched: Split out __schedule() deactivate task logic into a helper

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[ Upstream commit 7b3d61f6578ab06f130ecc13cd2f3010a6c295bb ]

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

Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Metin Kaya <metin.kaya@arm.com>
Reviewed-by: Qais Yousef <qyousef@layalina.io>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Metin Kaya <metin.kaya@arm.com>
Link: https://lore.kernel.org/r/20241009235352.1614323-7-jstultz@google.com
Stable-dep-of: 7d9da040575b ("psi: Fix race when task wakes up before psi_sched_switch() adjusts flags")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
John Stultz
2024-10-09 16:53:39 -07:00
committed by Greg Kroah-Hartman
parent c572fb9437
commit fd2818c5e0
1 changed files with 40 additions and 27 deletions
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67
kernel/sched/core.c
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@@ -6507,6 +6507,45 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
#define SM_PREEMPT 1
#define SM_RTLOCK_WAIT 2
/*
* Helper function for __schedule()
*
* If a task does not have signals pending, deactivate it
* Otherwise marks the task's __state as RUNNING
*/
static bool try_to_block_task(struct rq *rq, struct task_struct *p,
unsigned long task_state)
{
int flags = DEQUEUE_NOCLOCK;
if (signal_pending_state(task_state, p)) {
WRITE_ONCE(p->__state, TASK_RUNNING);
return false;
}
p->sched_contributes_to_load =
(task_state & TASK_UNINTERRUPTIBLE) &&
!(task_state & TASK_NOLOAD) &&
!(task_state & TASK_FROZEN);
if (unlikely(is_special_task_state(task_state)))
flags |= DEQUEUE_SPECIAL;
/*
* __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.
*/
block_task(rq, p, flags);
return true;
}
/*
* __schedule() is the main scheduler function.
*
@@ -6615,33 +6654,7 @@ static void __sched notrace __schedule(int sched_mode)
goto picked;
}
} else if (!preempt && prev_state) {
if (signal_pending_state(prev_state, prev)) {
WRITE_ONCE(prev->__state, TASK_RUNNING);
} else {
int flags = DEQUEUE_NOCLOCK;
prev->sched_contributes_to_load =
(prev_state & TASK_UNINTERRUPTIBLE) &&
!(prev_state & TASK_NOLOAD) &&
!(prev_state & TASK_FROZEN);
if (unlikely(is_special_task_state(prev_state)))
flags |= DEQUEUE_SPECIAL;
/*
* __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.
*/
block_task(rq, prev, flags);
block = true;
}
block = try_to_block_task(rq, prev, prev_state);
switch_count = &prev->nvcsw;
}