[PATCH net v3 11/11] rxrpc: Fix rxrpc_rotate_tx_rotate() to check there's something to rotate

[David Howells]

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@xxxxxxxxxx>
cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: Jeffrey Altman <jaltman@xxxxxxxxxxxx>
cc: Eric Dumazet <edumazet@xxxxxxxxxx>
cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
cc: Jakub Kicinski <kuba@xxxxxxxxxx>
cc: Paolo Abeni <pabeni@xxxxxxxxxx>
cc: Simon Horman <horms@xxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
cc: stable@xxxxxxxxxx
---
 net/rxrpc/input.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 9bd0f1b92463..73cafe6bfa9f 100644
--- 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).
 	 */