[PATCH 5.15 215/843] afs: Fix further netns teardown to cancel the preallocation charger

[Greg Kroah-Hartman]

5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells at redhat.com>

commit 2daf8ac812c3d78c642fe7652f62e29df5e3da20 upstream.

When an afs network namespace is torn down, it cancels and waits for the
work item that keeps the preallocated rxrpc call/conn/peer queue charged
before disabling incoming (i.e. listen 0), but there's a small window in
which it can be requeued by an incoming call wending through the I/O
thread.

Fix this by cancelling the charger work item again after reducing the
listen backlog to zero.

Fixes: 47694fbc9d24 ("afs: Fix netns teardown to cancel the preallocation charger")
Reported-by: Jakub Kicinski <kuba at kernel.org>
Signed-off-by: David Howells <dhowells at redhat.com>
Link: https://sashiko.dev/#/patchset/20260609140911.838677-1-dhowells%40redhat.com
cc: Li Daming <d4n.for.sec at gmail.com>
cc: Ren Wei <n05ec at lzu.edu.cn>
cc: Marc Dionne <marc.dionne at auristor.com>
cc: Jeffrey Altman <jaltman at auristor.com>
cc: Simon Horman <horms at kernel.org>
cc: linux-afs at lists.infradead.org
cc: stable at kernel.org
Link: https://patch.msgid.link/20260624163819.3017002-5-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 fs/afs/rxrpc.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -108,8 +108,13 @@ void afs_close_socket(struct afs_net *ne
 	_enter("");
 
 	cancel_work_sync(&net->charge_preallocation_work);
+	/* Future work items should now see ->live is false. */
+
 	kernel_listen(net->socket, 0);
+
+	/* Make sure work items are no longer running. */
 	flush_workqueue(afs_async_calls);
+	cancel_work_sync(&net->charge_preallocation_work);
 
 	if (net->spare_incoming_call) {
 		afs_put_call(net->spare_incoming_call);