From a4989fa91110508b64eea7ccde63d062113988ff Mon Sep 17 00:00:00 2001 From: Martin Schiller Date: Thu, 26 Nov 2020 07:35:54 +0100 Subject: net/lapb: support netdev events This patch allows layer2 (LAPB) to react to netdev events itself and avoids the detour via layer3 (X.25). 1. Establish layer2 on NETDEV_UP events, if the carrier is already up. 2. Call lapb_disconnect_request() on NETDEV_GOING_DOWN events to signal the peer that the connection will go down. (Only when the carrier is up.) 3. When a NETDEV_DOWN event occur, clear all queues, enter state LAPB_STATE_0 and stop all timers. 4. The NETDEV_CHANGE event makes it possible to handle carrier loss and detection. In case of Carrier Loss, clear all queues, enter state LAPB_STATE_0 and stop all timers. In case of Carrier Detection, we start timer t1 on a DCE interface, and on a DTE interface we change to state LAPB_STATE_1 and start sending SABM(E). Signed-off-by: Martin Schiller Acked-by: Xie He Signed-off-by: Jakub Kicinski --- net/lapb/lapb_iface.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 81 insertions(+), 1 deletion(-) (limited to 'net/lapb') diff --git a/net/lapb/lapb_iface.c b/net/lapb/lapb_iface.c index 3c03f6512c5f..213ea7abc9ab 100644 --- a/net/lapb/lapb_iface.c +++ b/net/lapb/lapb_iface.c @@ -418,14 +418,94 @@ int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb) return used; } +/* Handle device status changes. */ +static int lapb_device_event(struct notifier_block *this, unsigned long event, + void *ptr) +{ + struct net_device *dev = netdev_notifier_info_to_dev(ptr); + struct lapb_cb *lapb; + + if (!net_eq(dev_net(dev), &init_net)) + return NOTIFY_DONE; + + if (dev->type != ARPHRD_X25) + return NOTIFY_DONE; + + lapb = lapb_devtostruct(dev); + if (!lapb) + return NOTIFY_DONE; + + switch (event) { + case NETDEV_UP: + lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name); + + if (netif_carrier_ok(dev)) { + lapb_dbg(0, "(%p): Carrier is already up: %s\n", dev, + dev->name); + if (lapb->mode & LAPB_DCE) { + lapb_start_t1timer(lapb); + } else { + if (lapb->state == LAPB_STATE_0) { + lapb->state = LAPB_STATE_1; + lapb_establish_data_link(lapb); + } + } + } + break; + case NETDEV_GOING_DOWN: + if (netif_carrier_ok(dev)) + lapb_disconnect_request(dev); + break; + case NETDEV_DOWN: + lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name); + lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state); + lapb_clear_queues(lapb); + lapb->state = LAPB_STATE_0; + lapb->n2count = 0; + lapb_stop_t1timer(lapb); + lapb_stop_t2timer(lapb); + break; + case NETDEV_CHANGE: + if (netif_carrier_ok(dev)) { + lapb_dbg(0, "(%p): Carrier detected: %s\n", dev, + dev->name); + if (lapb->mode & LAPB_DCE) { + lapb_start_t1timer(lapb); + } else { + if (lapb->state == LAPB_STATE_0) { + lapb->state = LAPB_STATE_1; + lapb_establish_data_link(lapb); + } + } + } else { + lapb_dbg(0, "(%p) Carrier lost: %s\n", dev, dev->name); + lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state); + lapb_clear_queues(lapb); + lapb->state = LAPB_STATE_0; + lapb->n2count = 0; + lapb_stop_t1timer(lapb); + lapb_stop_t2timer(lapb); + } + break; + } + + return NOTIFY_DONE; +} + +static struct notifier_block lapb_dev_notifier = { + .notifier_call = lapb_device_event, +}; + static int __init lapb_init(void) { - return 0; + return register_netdevice_notifier(&lapb_dev_notifier); } static void __exit lapb_exit(void) { WARN_ON(!list_empty(&lapb_list)); + + unregister_netdevice_notifier(&lapb_dev_notifier); } MODULE_AUTHOR("Jonathan Naylor "); -- cgit v1.2.3 From 62480b992ba3fb1d7260b11293aed9d6557831c7 Mon Sep 17 00:00:00 2001 From: Martin Schiller Date: Thu, 26 Nov 2020 07:35:55 +0100 Subject: net/lapb: fix t1 timer handling for LAPB_STATE_0 1. DTE interface changes immediately to LAPB_STATE_1 and start sending SABM(E). 2. DCE interface sends N2-times DM and changes to LAPB_STATE_1 afterwards if there is no response in the meantime. Signed-off-by: Martin Schiller Signed-off-by: Jakub Kicinski --- net/lapb/lapb_timer.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'net/lapb') diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c index 8f5b17001a07..baa247fe4ed0 100644 --- a/net/lapb/lapb_timer.c +++ b/net/lapb/lapb_timer.c @@ -85,11 +85,18 @@ static void lapb_t1timer_expiry(struct timer_list *t) switch (lapb->state) { /* - * If we are a DCE, keep going DM .. DM .. DM + * If we are a DCE, send DM up to N2 times, then switch to + * STATE_1 and send SABM(E). */ case LAPB_STATE_0: - if (lapb->mode & LAPB_DCE) + if (lapb->mode & LAPB_DCE && + lapb->n2count != lapb->n2) { + lapb->n2count++; lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); + } else { + lapb->state = LAPB_STATE_1; + lapb_establish_data_link(lapb); + } break; /* -- cgit v1.2.3