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linux-next/drivers/net/usb/ipheth.c
Bernd Eckstein 94d250fae4 usbnet: ipheth: fix racing condition 
Fix a racing condition in ipheth.c that can lead to slow performance.

Bug: In ipheth_tx(), netif_wake_queue() may be called on the callback
ipheth_sndbulk_callback(), _before_ netif_stop_queue() is called.
When this happens, the queue is stopped longer than it needs to be,
thus reducing network performance.

Fix: Move netif_stop_queue() in front of usb_submit_urb(). Now the order
is always correct. In case, usb_submit_urb() fails, the queue is woken up
again as callback will not fire.

Testing: This racing condition is usually not noticeable, as it has to
occur very frequently to slowdown the network. The callback from the USB
is usually triggered slow enough, so the situation does not appear.
However, on a Ubuntu Linux on VMWare Workstation, running on Windows 10,
the we loose the race quite often and the following speedup can be noticed:

Without this patch: Download:  4.10 Mbit/s, Upload:  4.01 Mbit/s
With this patch:    Download: 36.23 Mbit/s, Upload: 17.61 Mbit/s

Signed-off-by: Oliver Zweigle <Oliver.Zweigle@faro.com>
Signed-off-by: Bernd Eckstein <3ernd.Eckstein@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-21 13:10:52 -07:00

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/*
* ipheth.c - Apple iPhone USB Ethernet driver
*
* Copyright (c) 2009 Diego Giagio <diego@giagio.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of GIAGIO.COM nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* The provided data structures and external interfaces from this code
* are not restricted to be used by modules with a GPL compatible license.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
*
* Attention: iPhone device must be paired, otherwise it won't respond to our
* driver. For more info: http://giagio.com/wiki/moin.cgi/iPhoneEthernetDriver
*
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/usb.h>
#include <linux/workqueue.h>
#define USB_VENDOR_APPLE 0x05ac
#define IPHETH_USBINTF_CLASS 255
#define IPHETH_USBINTF_SUBCLASS 253
#define IPHETH_USBINTF_PROTO 1
#define IPHETH_BUF_SIZE 1516
#define IPHETH_IP_ALIGN 2 /* padding at front of URB */
#define IPHETH_TX_TIMEOUT (5 * HZ)
#define IPHETH_INTFNUM 2
#define IPHETH_ALT_INTFNUM 1
#define IPHETH_CTRL_ENDP 0x00
#define IPHETH_CTRL_BUF_SIZE 0x40
#define IPHETH_CTRL_TIMEOUT (5 * HZ)
#define IPHETH_CMD_GET_MACADDR 0x00
#define IPHETH_CMD_CARRIER_CHECK 0x45
#define IPHETH_CARRIER_CHECK_TIMEOUT round_jiffies_relative(1 * HZ)
#define IPHETH_CARRIER_ON 0x04
static const struct usb_device_id ipheth_table[] = {
{ USB_VENDOR_AND_INTERFACE_INFO(USB_VENDOR_APPLE, IPHETH_USBINTF_CLASS,
IPHETH_USBINTF_SUBCLASS,
IPHETH_USBINTF_PROTO) },
{ }
};
MODULE_DEVICE_TABLE(usb, ipheth_table);
struct ipheth_device {
struct usb_device *udev;
struct usb_interface *intf;
struct net_device *net;
struct urb *tx_urb;
struct urb *rx_urb;
unsigned char *tx_buf;
unsigned char *rx_buf;
unsigned char *ctrl_buf;
u8 bulk_in;
u8 bulk_out;
struct delayed_work carrier_work;
bool confirmed_pairing;
};
static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags);
static int ipheth_alloc_urbs(struct ipheth_device *iphone)
{
struct urb *tx_urb = NULL;
struct urb *rx_urb = NULL;
u8 *tx_buf = NULL;
u8 *rx_buf = NULL;
tx_urb = usb_alloc_urb(0, GFP_KERNEL);
if (tx_urb == NULL)
goto error_nomem;
rx_urb = usb_alloc_urb(0, GFP_KERNEL);
if (rx_urb == NULL)
goto free_tx_urb;
tx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE,
GFP_KERNEL, &tx_urb->transfer_dma);
if (tx_buf == NULL)
goto free_rx_urb;
rx_buf = usb_alloc_coherent(iphone->udev, IPHETH_BUF_SIZE,
GFP_KERNEL, &rx_urb->transfer_dma);
if (rx_buf == NULL)
goto free_tx_buf;
iphone->tx_urb = tx_urb;
iphone->rx_urb = rx_urb;
iphone->tx_buf = tx_buf;
iphone->rx_buf = rx_buf;
return 0;
free_tx_buf:
usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, tx_buf,
tx_urb->transfer_dma);
free_rx_urb:
usb_free_urb(rx_urb);
free_tx_urb:
usb_free_urb(tx_urb);
error_nomem:
return -ENOMEM;
}
static void ipheth_free_urbs(struct ipheth_device *iphone)
{
usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->rx_buf,
iphone->rx_urb->transfer_dma);
usb_free_coherent(iphone->udev, IPHETH_BUF_SIZE, iphone->tx_buf,
iphone->tx_urb->transfer_dma);
usb_free_urb(iphone->rx_urb);
usb_free_urb(iphone->tx_urb);
}
static void ipheth_kill_urbs(struct ipheth_device *dev)
{
usb_kill_urb(dev->tx_urb);
usb_kill_urb(dev->rx_urb);
}
static void ipheth_rcvbulk_callback(struct urb *urb)
{
struct ipheth_device *dev;
struct sk_buff *skb;
int status;
char *buf;
int len;
dev = urb->context;
if (dev == NULL)
return;
status = urb->status;
switch (status) {
case -ENOENT:
case -ECONNRESET:
case -ESHUTDOWN:
case -EPROTO:
return;
case 0:
break;
default:
dev_err(&dev->intf->dev, "%s: urb status: %d\n",
__func__, status);
return;
}
if (urb->actual_length <= IPHETH_IP_ALIGN) {
dev->net->stats.rx_length_errors++;
return;
}
len = urb->actual_length - IPHETH_IP_ALIGN;
buf = urb->transfer_buffer + IPHETH_IP_ALIGN;
skb = dev_alloc_skb(len);
if (!skb) {
dev_err(&dev->intf->dev, "%s: dev_alloc_skb: -ENOMEM\n",
__func__);
dev->net->stats.rx_dropped++;
return;
}
skb_put_data(skb, buf, len);
skb->dev = dev->net;
skb->protocol = eth_type_trans(skb, dev->net);
dev->net->stats.rx_packets++;
dev->net->stats.rx_bytes += len;
dev->confirmed_pairing = true;
netif_rx(skb);
ipheth_rx_submit(dev, GFP_ATOMIC);
}
static void ipheth_sndbulk_callback(struct urb *urb)
{
struct ipheth_device *dev;
int status = urb->status;
dev = urb->context;
if (dev == NULL)
return;
if (status != 0 &&
status != -ENOENT &&
status != -ECONNRESET &&
status != -ESHUTDOWN)
dev_err(&dev->intf->dev, "%s: urb status: %d\n",
__func__, status);
if (status == 0)
netif_wake_queue(dev->net);
else
// on URB error, trigger immediate poll
schedule_delayed_work(&dev->carrier_work, 0);
}
static int ipheth_carrier_set(struct ipheth_device *dev)
{
struct usb_device *udev;
int retval;
if (!dev->confirmed_pairing)
return 0;
udev = dev->udev;
retval = usb_control_msg(udev,
usb_rcvctrlpipe(udev, IPHETH_CTRL_ENDP),
IPHETH_CMD_CARRIER_CHECK, /* request */
0xc0, /* request type */
0x00, /* value */
0x02, /* index */
dev->ctrl_buf, IPHETH_CTRL_BUF_SIZE,
IPHETH_CTRL_TIMEOUT);
if (retval < 0) {
dev_err(&dev->intf->dev, "%s: usb_control_msg: %d\n",
__func__, retval);
return retval;
}
if (dev->ctrl_buf[0] == IPHETH_CARRIER_ON) {
netif_carrier_on(dev->net);
if (dev->tx_urb->status != -EINPROGRESS)
netif_wake_queue(dev->net);
} else {
netif_carrier_off(dev->net);
netif_stop_queue(dev->net);
}
return 0;
}
static void ipheth_carrier_check_work(struct work_struct *work)
{
struct ipheth_device *dev = container_of(work, struct ipheth_device,
carrier_work.work);
ipheth_carrier_set(dev);
schedule_delayed_work(&dev->carrier_work, IPHETH_CARRIER_CHECK_TIMEOUT);
}
static int ipheth_get_macaddr(struct ipheth_device *dev)
{
struct usb_device *udev = dev->udev;
struct net_device *net = dev->net;
int retval;
retval = usb_control_msg(udev,
usb_rcvctrlpipe(udev, IPHETH_CTRL_ENDP),
IPHETH_CMD_GET_MACADDR, /* request */
0xc0, /* request type */
0x00, /* value */
0x02, /* index */
dev->ctrl_buf,
IPHETH_CTRL_BUF_SIZE,
IPHETH_CTRL_TIMEOUT);
if (retval < 0) {
dev_err(&dev->intf->dev, "%s: usb_control_msg: %d\n",
__func__, retval);
} else if (retval < ETH_ALEN) {
dev_err(&dev->intf->dev,
"%s: usb_control_msg: short packet: %d bytes\n",
__func__, retval);
retval = -EINVAL;
} else {
memcpy(net->dev_addr, dev->ctrl_buf, ETH_ALEN);
retval = 0;
}
return retval;
}
static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags)
{
struct usb_device *udev = dev->udev;
int retval;
usb_fill_bulk_urb(dev->rx_urb, udev,
usb_rcvbulkpipe(udev, dev->bulk_in),
dev->rx_buf, IPHETH_BUF_SIZE,
ipheth_rcvbulk_callback,
dev);
dev->rx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
retval = usb_submit_urb(dev->rx_urb, mem_flags);
if (retval)
dev_err(&dev->intf->dev, "%s: usb_submit_urb: %d\n",
__func__, retval);
return retval;
}
static int ipheth_open(struct net_device *net)
{
struct ipheth_device *dev = netdev_priv(net);
struct usb_device *udev = dev->udev;
int retval = 0;
usb_set_interface(udev, IPHETH_INTFNUM, IPHETH_ALT_INTFNUM);
retval = ipheth_carrier_set(dev);
if (retval)
return retval;
retval = ipheth_rx_submit(dev, GFP_KERNEL);
if (retval)
return retval;
schedule_delayed_work(&dev->carrier_work, IPHETH_CARRIER_CHECK_TIMEOUT);
return retval;
}
static int ipheth_close(struct net_device *net)
{
struct ipheth_device *dev = netdev_priv(net);
cancel_delayed_work_sync(&dev->carrier_work);
netif_stop_queue(net);
return 0;
}
static int ipheth_tx(struct sk_buff *skb, struct net_device *net)
{
struct ipheth_device *dev = netdev_priv(net);
struct usb_device *udev = dev->udev;
int retval;
/* Paranoid */
if (skb->len > IPHETH_BUF_SIZE) {
WARN(1, "%s: skb too large: %d bytes\n", __func__, skb->len);
dev->net->stats.tx_dropped++;
dev_kfree_skb_any(skb);
return NETDEV_TX_OK;
}
memcpy(dev->tx_buf, skb->data, skb->len);
if (skb->len < IPHETH_BUF_SIZE)
memset(dev->tx_buf + skb->len, 0, IPHETH_BUF_SIZE - skb->len);
usb_fill_bulk_urb(dev->tx_urb, udev,
usb_sndbulkpipe(udev, dev->bulk_out),
dev->tx_buf, IPHETH_BUF_SIZE,
ipheth_sndbulk_callback,
dev);
dev->tx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
netif_stop_queue(net);
retval = usb_submit_urb(dev->tx_urb, GFP_ATOMIC);
if (retval) {
dev_err(&dev->intf->dev, "%s: usb_submit_urb: %d\n",
__func__, retval);
dev->net->stats.tx_errors++;
dev_kfree_skb_any(skb);
netif_wake_queue(net);
} else {
dev->net->stats.tx_packets++;
dev->net->stats.tx_bytes += skb->len;
dev_consume_skb_any(skb);
}
return NETDEV_TX_OK;
}
static void ipheth_tx_timeout(struct net_device *net)
{
struct ipheth_device *dev = netdev_priv(net);
dev_err(&dev->intf->dev, "%s: TX timeout\n", __func__);
dev->net->stats.tx_errors++;
usb_unlink_urb(dev->tx_urb);
}
static u32 ipheth_ethtool_op_get_link(struct net_device *net)
{
struct ipheth_device *dev = netdev_priv(net);
return netif_carrier_ok(dev->net);
}
static const struct ethtool_ops ops = {
.get_link = ipheth_ethtool_op_get_link
};
static const struct net_device_ops ipheth_netdev_ops = {
.ndo_open = ipheth_open,
.ndo_stop = ipheth_close,
.ndo_start_xmit = ipheth_tx,
.ndo_tx_timeout = ipheth_tx_timeout,
};
static int ipheth_probe(struct usb_interface *intf,
const struct usb_device_id *id)
{
struct usb_device *udev = interface_to_usbdev(intf);
struct usb_host_interface *hintf;
struct usb_endpoint_descriptor *endp;
struct ipheth_device *dev;
struct net_device *netdev;
int i;
int retval;
netdev = alloc_etherdev(sizeof(struct ipheth_device));
if (!netdev)
return -ENOMEM;
netdev->netdev_ops = &ipheth_netdev_ops;
netdev->watchdog_timeo = IPHETH_TX_TIMEOUT;
strcpy(netdev->name, "eth%d");
dev = netdev_priv(netdev);
dev->udev = udev;
dev->net = netdev;
dev->intf = intf;
dev->confirmed_pairing = false;
/* Set up endpoints */
hintf = usb_altnum_to_altsetting(intf, IPHETH_ALT_INTFNUM);
if (hintf == NULL) {
retval = -ENODEV;
dev_err(&intf->dev, "Unable to find alternate settings interface\n");
goto err_endpoints;
}
for (i = 0; i < hintf->desc.bNumEndpoints; i++) {
endp = &hintf->endpoint[i].desc;
if (usb_endpoint_is_bulk_in(endp))
dev->bulk_in = endp->bEndpointAddress;
else if (usb_endpoint_is_bulk_out(endp))
dev->bulk_out = endp->bEndpointAddress;
}
if (!(dev->bulk_in && dev->bulk_out)) {
retval = -ENODEV;
dev_err(&intf->dev, "Unable to find endpoints\n");
goto err_endpoints;
}
dev->ctrl_buf = kmalloc(IPHETH_CTRL_BUF_SIZE, GFP_KERNEL);
if (dev->ctrl_buf == NULL) {
retval = -ENOMEM;
goto err_alloc_ctrl_buf;
}
retval = ipheth_get_macaddr(dev);
if (retval)
goto err_get_macaddr;
INIT_DELAYED_WORK(&dev->carrier_work, ipheth_carrier_check_work);
retval = ipheth_alloc_urbs(dev);
if (retval) {
dev_err(&intf->dev, "error allocating urbs: %d\n", retval);
goto err_alloc_urbs;
}
usb_set_intfdata(intf, dev);
SET_NETDEV_DEV(netdev, &intf->dev);
netdev->ethtool_ops = &ops;
retval = register_netdev(netdev);
if (retval) {
dev_err(&intf->dev, "error registering netdev: %d\n", retval);
retval = -EIO;
goto err_register_netdev;
}
// carrier down and transmit queues stopped until packet from device
netif_carrier_off(netdev);
netif_tx_stop_all_queues(netdev);
dev_info(&intf->dev, "Apple iPhone USB Ethernet device attached\n");
return 0;
err_register_netdev:
ipheth_free_urbs(dev);
err_alloc_urbs:
err_get_macaddr:
err_alloc_ctrl_buf:
kfree(dev->ctrl_buf);
err_endpoints:
free_netdev(netdev);
return retval;
}
static void ipheth_disconnect(struct usb_interface *intf)
{
struct ipheth_device *dev;
dev = usb_get_intfdata(intf);
if (dev != NULL) {
unregister_netdev(dev->net);
ipheth_kill_urbs(dev);
ipheth_free_urbs(dev);
kfree(dev->ctrl_buf);
free_netdev(dev->net);
}
usb_set_intfdata(intf, NULL);
dev_info(&intf->dev, "Apple iPhone USB Ethernet now disconnected\n");
}
static struct usb_driver ipheth_driver = {
.name = "ipheth",
.probe = ipheth_probe,
.disconnect = ipheth_disconnect,
.id_table = ipheth_table,
.disable_hub_initiated_lpm = 1,
};
module_usb_driver(ipheth_driver);
MODULE_AUTHOR("Diego Giagio <diego@giagio.com>");
MODULE_DESCRIPTION("Apple iPhone USB Ethernet driver");
MODULE_LICENSE("Dual BSD/GPL");
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