linux-kernel - [tip: sched/core] sched: Change wait_task_inactive()s match

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Date:   Fri, 09 Sep 2022 09:00:22 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched: Change wait_task_inactive()s match_state

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     9204a97f7ae862fc8a3330ec8335917534c3fb63
Gitweb:        https://git.kernel.org/tip/9204a97f7ae862fc8a3330ec8335917534c3fb63
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Mon, 22 Aug 2022 13:18:19 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 07 Sep 2022 21:53:48 +02:00

sched: Change wait_task_inactive()s match_state

Make wait_task_inactive()'s @match_state work like ttwu()'s @state.

That is, instead of an equal comparison, use it as a mask. This allows
matching multiple block conditions.

(removes the unlikely; it doesn't make sense how it's only part of the
condition)

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20220822114648.856734578@infradead.org
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1630181..43d71c6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3294,7 +3294,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state
 		 * is actually now running somewhere else!
 		 */
 		while (task_on_cpu(rq, p)) {
-			if (match_state && unlikely(READ_ONCE(p->__state) != match_state))
+			if (match_state && !(READ_ONCE(p->__state) & match_state))
 				return 0;
 			cpu_relax();
 		}
@@ -3309,7 +3309,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state
 		running = task_on_cpu(rq, p);
 		queued = task_on_rq_queued(p);
 		ncsw = 0;
-		if (!match_state || READ_ONCE(p->__state) == match_state)
+		if (!match_state || (READ_ONCE(p->__state) & match_state))
 			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
 		task_rq_unlock(rq, p, &rf);