rxrpc: Fix rxrpc_rotate_tx_rotate() to check there's something to rotate

Fix rxrpc_rotate_tx_rotate() to check that there's something in the
transmission buffer to be rotated before it attempts to rotate anything.

Fixes: b341a0263b1b ("rxrpc: Implement progressive transmission queue struct")
Link: https://sashiko.dev/#/patchset/20260618134802.2477777-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260624163819.3017002-12-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 9bd0f1b92463c82370aec749dfc225e4d656a8fb..73cafe6bfa9f54765f47c5ab2662f2eef4adb9af 100644 (file)
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -237,6 +237,9 @@ static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
                call->acks_lowest_nak = to;
        }
 
+       if (after(seq, to))
+               return false;
+
        /* We may have a left over fully-consumed buffer at the front that we
         * couldn't drop before (rotate_and_keep below).
         */