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: 248f657 ("netpoll: Optimize skb refilling on critical path")
Signed-off-by: Breno Leitao <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: leitao

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);