netdev - [PATCH net-next 1/3] net: netpoll: Defer skb_pool population until setup success

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Message-ID: <20241025142025.3558051-2-leitao@debian.org>
Date: Fri, 25 Oct 2024 07:20:18 -0700
From: Breno Leitao <leitao@...ian.org>
To: kuba@...nel.org,
	horms@...nel.org,
	davem@...emloft.net,
	edumazet@...gle.com,
	pabeni@...hat.com
Cc: thepacketgeek@...il.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	davej@...emonkey.org.uk,
	vlad.wing@...il.com,
	max@...sevol.com,
	kernel-team@...a.com,
	jiri@...nulli.us,
	jv@...sburgh.net,
	andy@...yhouse.net,
	aehkn@...hub.one,
	Rik van Riel <riel@...riel.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH net-next 1/3] net: netpoll: Defer skb_pool population until setup success

The current implementation has a flaw where it populates the skb_pool
with 32 SKBs before calling __netpoll_setup(). If the setup fails, the
skb_pool buffer will persist indefinitely and never be cleaned up.

This change moves the skb_pool population to after the successful
completion of __netpoll_setup(), ensuring that the buffers are not
unnecessarily retained. Additionally, this modification alleviates rtnl
lock pressure by allowing the buffer filling to occur outside of the
lock.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 net/core/netpoll.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index aa49b92e9194..e83fd8bdce36 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -772,13 +772,13 @@ int netpoll_setup(struct netpoll *np)
 		}
 	}
 
-	/* fill up the skb queue */
-	refill_skbs();
-
 	err = __netpoll_setup(np, ndev);
 	if (err)
 		goto put;
 	rtnl_unlock();
+
+	/* fill up the skb queue */
+	refill_skbs();
 	return 0;
 
 put:
-- 
2.43.5