linux-kernel - [PATCH net] net: netpoll: initialize work queue before error checks

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Message-Id: <20251127-netpoll_fix_init_work-v1-1-65c07806d736@debian.org>
Date: Thu, 27 Nov 2025 07:30:15 -0800
From: Breno Leitao <leitao@...ian.org>
To: "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 gustavold@...il.com, asantostc@...il.com, kernel-team@...a.com, 
 Breno Leitao <leitao@...ian.org>
Subject: [PATCH net] net: netpoll: initialize work queue before error
 checks

Prevent a kernel warning when netconsole setup fails on devices with
IFF_DISABLE_NETPOLL flag. The warning (at kernel/workqueue.c:4242 in
__flush_work) occurs because the cleanup path tries to cancel an
uninitialized work queue.

When __netpoll_setup() encounters a device with IFF_DISABLE_NETPOLL,
it fails early and calls skb_pool_flush() for cleanup. This function
calls cancel_work_sync(&np->refill_wq), but refill_wq hasn't been
initialized yet, triggering the warning.

Move INIT_WORK() to the beginning of __netpoll_setup(), ensuring the
work queue is properly initialized before any potential failure points.
This allows the cleanup path to safely cancel the work queue regardless
of where the setup fails.

Fixes: 248f6571fd4c5 ("netpoll: Optimize skb refilling on critical path")
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 net/core/netpoll.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 331764845e8f..09f72f10813c 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -554,6 +554,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
 	int err;

 	skb_queue_head_init(&np->skb_pool);
+	INIT_WORK(&np->refill_wq, refill_skbs_work_handler);

 	if (ndev->priv_flags & IFF_DISABLE_NETPOLL) {
 		np_err(np, "%s doesn't support polling, aborting\n",
@@ -591,7 +592,6 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)

 	/* fill up the skb queue */
 	refill_skbs(np);
-	INIT_WORK(&np->refill_wq, refill_skbs_work_handler);

 	/* last thing to do is link it to the net device structure */
 	rcu_assign_pointer(ndev->npinfo, npinfo);

---
base-commit: f07f4ea53e22429c84b20832fa098b5ecc0d4e35
change-id: 20251127-netpoll_fix_init_work-5e4df6c57cf2

Best regards,
--  
Breno Leitao <leitao@...ian.org>