afs: Fix netns teardown to cancel the preallocation charger

commit 47694fb upstream.

Fix the teardown of an afs network namespace to make sure it cancels the
work item that keeps the preallocated rxrpc call/conn/peer queue charged
before incoming calls are disabled (i.e. listen 0).

Also, if net->live is false because the afs netns is being deleted, make
afs_charge_preallocation() skip charging and make afs_rx_new_call() avoid
requeuing the charger.

(This was found by AI review).

Fixes: 00e9071 ("rxrpc: Preallocate peers, conns and calls for incoming service requests")
Reported-by: Simon Horman <horms@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Li Daming <d4n.for.sec@gmail.com>
cc: Ren Wei <n05ec@lzu.edu.cn>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260609140911.838677-5-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: dhowells

fs/afs/rxrpc.c

@@ -109,6 +109,7 @@ void afs_close_socket(struct afs_net *net)
 {
 	_enter("");
 
+	cancel_work_sync(&net->charge_preallocation_work);
 	kernel_listen(net->socket, 0);
 	flush_workqueue(afs_async_calls);
 
@@ -727,7 +728,7 @@ void afs_charge_preallocation(struct work_struct *work)
 		container_of(work, struct afs_net, charge_preallocation_work);
 	struct afs_call *call = net->spare_incoming_call;
 
-	for (;;) {
+	while (READ_ONCE(net->live)) {
 		if (!call) {
 			call = afs_alloc_call(net, &afs_RXCMxxxx, GFP_KERNEL);
 			if (!call)
@@ -772,7 +773,8 @@ static void afs_rx_new_call(struct sock *sk, struct rxrpc_call *rxcall,
 {
 	struct afs_net *net = afs_sock2net(sk);
 
-	queue_work(afs_wq, &net->charge_preallocation_work);
+	if (net->live)
+		queue_work(afs_wq, &net->charge_preallocation_work);
 }
 
 /*