netdev - [PATCH net-next 7/8] rtnetlink: do not depend on RTNL in rtnl_xdp_prog

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Message-ID: <20240503192059.3884225-8-edumazet@google.com>
Date: Fri,  3 May 2024 19:20:58 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 7/8] rtnetlink: do not depend on RTNL in rtnl_xdp_prog_skb()

dev->xdp_prog is protected by RCU, we can lift RTNL requirement
from rtnl_xdp_prog_skb().

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/rtnetlink.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 6af7f00503b43d4989d0aaafc8b968216a6e77f5..66e5be7b92686deb03f58ee43c9707470b8c70d6 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1477,13 +1477,15 @@ static int rtnl_fill_link_ifmap(struct sk_buff *skb,
 static u32 rtnl_xdp_prog_skb(struct net_device *dev)
 {
 	const struct bpf_prog *generic_xdp_prog;
+	u32 res = 0;
 
-	ASSERT_RTNL();
+	rcu_read_lock();
+	generic_xdp_prog = rcu_dereference(dev->xdp_prog);
+	if (generic_xdp_prog)
+		res = generic_xdp_prog->aux->id;
+	rcu_read_unlock();
 
-	generic_xdp_prog = rtnl_dereference(dev->xdp_prog);
-	if (!generic_xdp_prog)
-		return 0;
-	return generic_xdp_prog->aux->id;
+	return res;
 }
 
 static u32 rtnl_xdp_prog_drv(struct net_device *dev)
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog