linux-kernel - [PATCH] irq_work: Replace wait loop with rcuwait_wait

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Message-ID:
 <SJ2P223MB10267BCF19A4A37747A52330F7632@SJ2P223MB1026.NAMP223.PROD.OUTLOOK.COM>
Date: Thu, 19 Sep 2024 11:43:26 -0400
From: Steven Davis <goldside000@...look.com>
To: akpm@...ux-foundation.org
Cc: ankur.a.arora@...cle.com,
	frederic@...nel.org,
	linux-kernel@...r.kernel.org,
	peterz@...radead.org,
	tglx@...utronix.de,
	Steven Davis <goldside000@...look.com>
Subject: [PATCH] irq_work: Replace wait loop with rcuwait_wait_event

The previous implementation of irq_work_sync used a busy-wait
loop with cpu_relax() to check the status of IRQ work. This
approach, while functional, could lead to inefficiencies in
CPU usage.

This commit replaces the busy-wait loop with the rcuwait_wait_event
mechanism. This change leverages the RCU wait mechanism to handle
waiting for IRQ work completion more efficiently, improving CPU
responsiveness and reducing unnecessary CPU usage.

Signed-off-by: Steven Davis <goldside000@...look.com>
---
 kernel/irq_work.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 2f4fb336dda1..2b092a1d07a9 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -295,8 +295,7 @@ void irq_work_sync(struct irq_work *work)
 		return;
 	}

-	while (irq_work_is_busy(work))
-		cpu_relax();
+	rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work), TASK_UNINTERRUPTIBLE);
 }
 EXPORT_SYMBOL_GPL(irq_work_sync);

-- 
2.39.5