https://github.com/torvalds/linux
Tip revision: 637f847b68741de42547d5f846c71ed5fe859b6e authored by TarAldarion on 02 March 2020, 12:13:05 UTC
Fix for packets being rejected in the ring buffer used by the xHCI controller. When a packet larger than MTU arrives in Linux from the modem, it is discarded with -EOVERFLOW error (Babble error). This is seen on USB3.0 and USB2.0 busses. This is essentially because the MRU (Max Receive Size) is not a separate entity to the MTU (Max Transmit Size) and the received packets can be larger than those transmitted. Following the babble error there were an endless supply of zero-length URBs which are rejected with -EPROTO (increasing the rx input error counter each time). This is only seen on USB3.0. These continue to come ad infinitum until the modem is shutdown. There appears to be a bug in the core USB handling code in Linux that doesn't deal well with network MTUs smaller than 1500 bytes. By default the dev->hard_mtu (the real MTU) is in lockstep with dev->rx_urb_size (essentially an MRU), and it's the latter that is causing trouble. This has nothing to do with the modems; the issue can be reproduced by getting a USB-Ethernet dongle, setting the MTU to 1430, and pinging with size greater than 1406.
Fix for packets being rejected in the ring buffer used by the xHCI controller. When a packet larger than MTU arrives in Linux from the modem, it is discarded with -EOVERFLOW error (Babble error). This is seen on USB3.0 and USB2.0 busses. This is essentially because the MRU (Max Receive Size) is not a separate entity to the MTU (Max Transmit Size) and the received packets can be larger than those transmitted. Following the babble error there were an endless supply of zero-length URBs which are rejected with -EPROTO (increasing the rx input error counter each time). This is only seen on USB3.0. These continue to come ad infinitum until the modem is shutdown. There appears to be a bug in the core USB handling code in Linux that doesn't deal well with network MTUs smaller than 1500 bytes. By default the dev->hard_mtu (the real MTU) is in lockstep with dev->rx_urb_size (essentially an MRU), and it's the latter that is causing trouble. This has nothing to do with the modems; the issue can be reproduced by getting a USB-Ethernet dongle, setting the MTU to 1430, and pinging with size greater than 1406.
Tip revision: 637f847
af_nfc.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2011 Instituto Nokia de Tecnologia
*
* Authors:
* Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
* Lauro Ramos Venancio <lauro.venancio@openbossa.org>
*/
#include <linux/nfc.h>
#include <linux/module.h>
#include "nfc.h"
static DEFINE_RWLOCK(proto_tab_lock);
static const struct nfc_protocol *proto_tab[NFC_SOCKPROTO_MAX];
static int nfc_sock_create(struct net *net, struct socket *sock, int proto,
int kern)
{
int rc = -EPROTONOSUPPORT;
if (net != &init_net)
return -EAFNOSUPPORT;
if (proto < 0 || proto >= NFC_SOCKPROTO_MAX)
return -EINVAL;
read_lock(&proto_tab_lock);
if (proto_tab[proto] && try_module_get(proto_tab[proto]->owner)) {
rc = proto_tab[proto]->create(net, sock, proto_tab[proto], kern);
module_put(proto_tab[proto]->owner);
}
read_unlock(&proto_tab_lock);
return rc;
}
static const struct net_proto_family nfc_sock_family_ops = {
.owner = THIS_MODULE,
.family = PF_NFC,
.create = nfc_sock_create,
};
int nfc_proto_register(const struct nfc_protocol *nfc_proto)
{
int rc;
if (nfc_proto->id < 0 || nfc_proto->id >= NFC_SOCKPROTO_MAX)
return -EINVAL;
rc = proto_register(nfc_proto->proto, 0);
if (rc)
return rc;
write_lock(&proto_tab_lock);
if (proto_tab[nfc_proto->id])
rc = -EBUSY;
else
proto_tab[nfc_proto->id] = nfc_proto;
write_unlock(&proto_tab_lock);
return rc;
}
EXPORT_SYMBOL(nfc_proto_register);
void nfc_proto_unregister(const struct nfc_protocol *nfc_proto)
{
write_lock(&proto_tab_lock);
proto_tab[nfc_proto->id] = NULL;
write_unlock(&proto_tab_lock);
proto_unregister(nfc_proto->proto);
}
EXPORT_SYMBOL(nfc_proto_unregister);
int __init af_nfc_init(void)
{
return sock_register(&nfc_sock_family_ops);
}
void af_nfc_exit(void)
{
sock_unregister(PF_NFC);
}