linux-kernel - [PATCH 4/9] softirq: Allow early break

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Date:   Fri, 5 May 2023 19:33:10 +0800
From:   Liu Jian <liujian56@...wei.com>
To:     <corbet@....net>, <paulmck@...nel.org>, <frederic@...nel.org>,
        <quic_neeraju@...cinc.com>, <joel@...lfernandes.org>,
        <josh@...htriplett.org>, <boqun.feng@...il.com>,
        <rostedt@...dmis.org>, <mathieu.desnoyers@...icios.com>,
        <jiangshanlai@...il.com>, <qiang1.zhang@...el.com>,
        <jstultz@...gle.com>, <tglx@...utronix.de>, <sboyd@...nel.org>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <peterz@...radead.org>, <frankwoo@...gle.com>,
        <Rhinewuwu@...gle.com>
CC:     <liujian56@...wei.com>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <rcu@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: [PATCH 4/9] softirq: Allow early break

From: Peter Zijlstra <peterz@...radead.org>

Allow terminating the softirq processing loop without finishing the
vectors.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Liu Jian <liujian56@...wei.com>
---
 kernel/softirq.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 48a81d8ae49a..e2cad5d108c8 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -582,6 +582,9 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 			       prev_count, preempt_count());
 			preempt_count_set(prev_count);
 		}
+
+		if (pending && __softirq_needs_break(start))
+			break;
 	}
 
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT) &&
@@ -590,13 +593,14 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 
 	local_irq_disable();
 
-	pending = local_softirq_pending();
-	if (pending) {
-		if (!__softirq_needs_break(start) && --max_restart)
-			goto restart;
+	if (pending)
+		or_softirq_pending(pending);
+	else if ((pending = local_softirq_pending()) &&
+		 !__softirq_needs_break(start) &&
+		 --max_restart)
+		goto restart;
 
-		wakeup_softirqd();
-	}
+	wakeup_softirqd();
 
 	account_softirq_exit(current);
 	lockdep_softirq_end(in_hardirq);
-- 
2.34.1