[PATCH] Bluetooth: l2cap: Fix MPS check in l2cap_ecred_reconf_req

[Dudu Lu <phx0fer@gmail.com>]

The L2CAP Enhanced Credit Based Flow Control specification (Core Spec
5.4, Vol 3, Part A, Section 7.11) states that if more than one channel
is being reconfigured, the MPS shall not be decreased. The current code
uses `&& i` (loop index) to approximate "more than one channel", but
this incorrectly allows MPS decrease for the first channel (i==0) even
when multiple channels are being reconfigured, and incorrectly blocks
MPS decrease for subsequent channels even when only that single channel
is being reconfigured via index > 0.

Replace `&& i` with `&& num_scid > 1` which correctly checks whether
the reconfiguration request covers more than one channel, matching the
specification intent.

Signed-off-by: Dudu Lu <phx0fer@gmail.com>
---
 net/bluetooth/l2cap_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 95c65fece39b..b069f965a339 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -5428,7 +5428,7 @@ static inline int l2cap_ecred_reconf_req(struct l2cap_conn *conn,
 		 * configured, the MPS field may be less than the current MPS
 		 * of that channel.
 		 */
-		if (chan[i]->remote_mps >= mps && i) {
+		if (chan[i]->remote_mps >= mps && num_scid > 1) {
 			BT_ERR("chan %p decreased MPS %u -> %u", chan[i],
 			       chan[i]->remote_mps, mps);
 			result = L2CAP_RECONF_INVALID_MPS;
-- 
2.39.3 (Apple Git-145)