[Bluetooth] Reduce L2CAP MTU for RFCOMM connections
This patch reduces the default L2CAP MTU for all RFCOMM connections
from 1024 to 1013 to improve the interoperability with some broken
RFCOMM implementations. To make this more flexible the L2CAP MTU
becomes also a module parameter and so it can changed at runtime.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h
index bbfac86..89d743c 100644
--- a/include/net/bluetooth/rfcomm.h
+++ b/include/net/bluetooth/rfcomm.h
@@ -33,7 +33,7 @@
#define RFCOMM_DEFAULT_MTU 127
#define RFCOMM_DEFAULT_CREDITS 7
-#define RFCOMM_MAX_L2CAP_MTU 1024
+#define RFCOMM_MAX_L2CAP_MTU 1013
#define RFCOMM_MAX_CREDITS 40
#define RFCOMM_SKB_HEAD_RESERVE 8
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index 0d89d64..5b4253c 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -46,13 +46,15 @@
#include <net/bluetooth/l2cap.h>
#include <net/bluetooth/rfcomm.h>
-#define VERSION "1.6"
-
#ifndef CONFIG_BT_RFCOMM_DEBUG
#undef BT_DBG
#define BT_DBG(D...)
#endif
+#define VERSION "1.7"
+
+static unsigned int l2cap_mtu = RFCOMM_MAX_L2CAP_MTU;
+
static struct task_struct *rfcomm_thread;
static DECLARE_MUTEX(rfcomm_sem);
@@ -623,7 +625,7 @@
/* Set L2CAP options */
sk = sock->sk;
lock_sock(sk);
- l2cap_pi(sk)->imtu = RFCOMM_MAX_L2CAP_MTU;
+ l2cap_pi(sk)->imtu = l2cap_mtu;
release_sock(sk);
s = rfcomm_session_add(sock, BT_BOUND);
@@ -1868,7 +1870,7 @@
/* Set L2CAP options */
sk = sock->sk;
lock_sock(sk);
- l2cap_pi(sk)->imtu = RFCOMM_MAX_L2CAP_MTU;
+ l2cap_pi(sk)->imtu = l2cap_mtu;
release_sock(sk);
/* Start listening on the socket */
@@ -2070,6 +2072,9 @@
module_init(rfcomm_init);
module_exit(rfcomm_exit);
+module_param(l2cap_mtu, uint, 0644);
+MODULE_PARM_DESC(l2cap_mtu, "Default MTU for the L2CAP connection");
+
MODULE_AUTHOR("Maxim Krasnyansky <maxk@qualcomm.com>, Marcel Holtmann <marcel@holtmann.org>");
MODULE_DESCRIPTION("Bluetooth RFCOMM ver " VERSION);
MODULE_VERSION(VERSION);