linux-kernel - [tip: sched/core] sched: Simplify try_steal

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Date:   Mon, 14 Aug 2023 15:08:04 -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>,
        Valentin Schneider <vschneid@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched: Simplify try_steal_cookie()

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

Commit-ID:     b4e1fa1e14286f7a825b10d8ebb2e9c0f77c241b
Gitweb:        https://git.kernel.org/tip/b4e1fa1e14286f7a825b10d8ebb2e9c0f77c241b
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Tue, 01 Aug 2023 22:41:29 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 14 Aug 2023 17:01:27 +02:00

sched: Simplify try_steal_cookie()

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Valentin Schneider <vschneid@...hat.com>
Link: https://lore.kernel.org/r/20230801211812.304154828@infradead.org
---
 kernel/sched/core.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1b2fa91..f113a44 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6298,19 +6298,19 @@ static bool try_steal_cookie(int this, int that)
 	unsigned long cookie;
 	bool success = false;
 
-	local_irq_disable();
-	double_rq_lock(dst, src);
+	guard(irq)();
+	guard(double_rq_lock)(dst, src);
 
 	cookie = dst->core->core_cookie;
 	if (!cookie)
-		goto unlock;
+		return false;
 
 	if (dst->curr != dst->idle)
-		goto unlock;
+		return false;
 
 	p = sched_core_find(src, cookie);
 	if (!p)
-		goto unlock;
+		return false;
 
 	do {
 		if (p == src->core_pick || p == src->curr)
@@ -6322,9 +6322,10 @@ static bool try_steal_cookie(int this, int that)
 		if (p->core_occupation > dst->idle->core_occupation)
 			goto next;
 		/*
-		 * sched_core_find() and sched_core_next() will ensure that task @p
-		 * is not throttled now, we also need to check whether the runqueue
-		 * of the destination CPU is being throttled.
+		 * sched_core_find() and sched_core_next() will ensure
+		 * that task @p is not throttled now, we also need to
+		 * check whether the runqueue of the destination CPU is
+		 * being throttled.
 		 */
 		if (sched_task_is_throttled(p, this))
 			goto next;
@@ -6342,10 +6343,6 @@ next:
 		p = sched_core_next(p, cookie);
 	} while (p);
 
-unlock:
-	double_rq_unlock(dst, src);
-	local_irq_enable();
-
 	return success;
 }