netdev - [PATCH net-next v2 3/3] net: rps: locklessly access rflow->cpu

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Message-Id: <20240417062721.45652-4-kerneljasonxing@gmail.com>
Date: Wed, 17 Apr 2024 14:27:21 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	horms@...nel.org
Cc: netdev@...r.kernel.org,
	kerneljasonxing@...il.com,
	Jason Xing <kernelxing@...cent.com>
Subject: [PATCH net-next v2 3/3] net: rps: locklessly access rflow->cpu

From: Jason Xing <kernelxing@...cent.com>

This is the last member in struct rps_dev_flow which should be
protected locklessly. So finish it.

Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
 net/core/dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 40a535158e45..aeb45025e2bc 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4533,7 +4533,7 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
 		rps_input_queue_tail_save(&rflow->last_qtail, head);
 	}
 
-	rflow->cpu = next_cpu;
+	WRITE_ONCE(rflow->cpu, next_cpu);
 	return rflow;
 }
 
@@ -4597,7 +4597,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
 		 * we can look at the local (per receive queue) flow table
 		 */
 		rflow = &flow_table->flows[hash & flow_table->mask];
-		tcpu = rflow->cpu;
+		tcpu = READ_ONCE(rflow->cpu);
 
 		/*
 		 * If the desired CPU (where last recvmsg was done) is
-- 
2.37.3