xref: /linux/drivers/net/usb/usbnet.c (revision c39b9fd728d8173ecda993524089fbc38211a17f)
1 /*
2  * USB Network driver infrastructure
3  * Copyright (C) 2000-2005 by David Brownell
4  * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19  */
20 
21 /*
22  * This is a generic "USB networking" framework that works with several
23  * kinds of full and high speed networking devices:  host-to-host cables,
24  * smart usb peripherals, and actual Ethernet adapters.
25  *
26  * These devices usually differ in terms of control protocols (if they
27  * even have one!) and sometimes they define new framing to wrap or batch
28  * Ethernet packets.  Otherwise, they talk to USB pretty much the same,
29  * so interface (un)binding, endpoint I/O queues, fault handling, and other
30  * issues can usefully be addressed by this framework.
31  */
32 
33 // #define	DEBUG			// error path messages, extra info
34 // #define	VERBOSE			// more; success messages
35 
36 #include <linux/module.h>
37 #include <linux/init.h>
38 #include <linux/netdevice.h>
39 #include <linux/etherdevice.h>
40 #include <linux/ctype.h>
41 #include <linux/ethtool.h>
42 #include <linux/workqueue.h>
43 #include <linux/mii.h>
44 #include <linux/usb.h>
45 #include <linux/usb/usbnet.h>
46 #include <linux/slab.h>
47 #include <linux/kernel.h>
48 #include <linux/pm_runtime.h>
49 
50 #define DRIVER_VERSION		"22-Aug-2005"
51 
52 
53 /*-------------------------------------------------------------------------*/
54 
55 /*
56  * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
57  * Several dozen bytes of IPv4 data can fit in two such transactions.
58  * One maximum size Ethernet packet takes twenty four of them.
59  * For high speed, each frame comfortably fits almost 36 max size
60  * Ethernet packets (so queues should be bigger).
61  *
62  * REVISIT qlens should be members of 'struct usbnet'; the goal is to
63  * let the USB host controller be busy for 5msec or more before an irq
64  * is required, under load.  Jumbograms change the equation.
65  */
66 #define RX_MAX_QUEUE_MEMORY (60 * 1518)
67 #define	RX_QLEN(dev) (((dev)->udev->speed == USB_SPEED_HIGH) ? \
68 			(RX_MAX_QUEUE_MEMORY/(dev)->rx_urb_size) : 4)
69 #define	TX_QLEN(dev) (((dev)->udev->speed == USB_SPEED_HIGH) ? \
70 			(RX_MAX_QUEUE_MEMORY/(dev)->hard_mtu) : 4)
71 
72 // reawaken network queue this soon after stopping; else watchdog barks
73 #define TX_TIMEOUT_JIFFIES	(5*HZ)
74 
75 // throttle rx/tx briefly after some faults, so khubd might disconnect()
76 // us (it polls at HZ/4 usually) before we report too many false errors.
77 #define THROTTLE_JIFFIES	(HZ/8)
78 
79 // between wakeups
80 #define UNLINK_TIMEOUT_MS	3
81 
82 /*-------------------------------------------------------------------------*/
83 
84 // randomly generated ethernet address
85 static u8	node_id [ETH_ALEN];
86 
87 static const char driver_name [] = "usbnet";
88 
89 /* use ethtool to change the level for any given device */
90 static int msg_level = -1;
91 module_param (msg_level, int, 0);
92 MODULE_PARM_DESC (msg_level, "Override default message level");
93 
94 /*-------------------------------------------------------------------------*/
95 
96 /* handles CDC Ethernet and many other network "bulk data" interfaces */
97 int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
98 {
99 	int				tmp;
100 	struct usb_host_interface	*alt = NULL;
101 	struct usb_host_endpoint	*in = NULL, *out = NULL;
102 	struct usb_host_endpoint	*status = NULL;
103 
104 	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
105 		unsigned	ep;
106 
107 		in = out = status = NULL;
108 		alt = intf->altsetting + tmp;
109 
110 		/* take the first altsetting with in-bulk + out-bulk;
111 		 * remember any status endpoint, just in case;
112 		 * ignore other endpoints and altsettings.
113 		 */
114 		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
115 			struct usb_host_endpoint	*e;
116 			int				intr = 0;
117 
118 			e = alt->endpoint + ep;
119 			switch (e->desc.bmAttributes) {
120 			case USB_ENDPOINT_XFER_INT:
121 				if (!usb_endpoint_dir_in(&e->desc))
122 					continue;
123 				intr = 1;
124 				/* FALLTHROUGH */
125 			case USB_ENDPOINT_XFER_BULK:
126 				break;
127 			default:
128 				continue;
129 			}
130 			if (usb_endpoint_dir_in(&e->desc)) {
131 				if (!intr && !in)
132 					in = e;
133 				else if (intr && !status)
134 					status = e;
135 			} else {
136 				if (!out)
137 					out = e;
138 			}
139 		}
140 		if (in && out)
141 			break;
142 	}
143 	if (!alt || !in || !out)
144 		return -EINVAL;
145 
146 	if (alt->desc.bAlternateSetting != 0 ||
147 	    !(dev->driver_info->flags & FLAG_NO_SETINT)) {
148 		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
149 				alt->desc.bAlternateSetting);
150 		if (tmp < 0)
151 			return tmp;
152 	}
153 
154 	dev->in = usb_rcvbulkpipe (dev->udev,
155 			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
156 	dev->out = usb_sndbulkpipe (dev->udev,
157 			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
158 	dev->status = status;
159 	return 0;
160 }
161 EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
162 
163 int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
164 {
165 	int 		tmp, i;
166 	unsigned char	buf [13];
167 
168 	tmp = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
169 	if (tmp != 12) {
170 		dev_dbg(&dev->udev->dev,
171 			"bad MAC string %d fetch, %d\n", iMACAddress, tmp);
172 		if (tmp >= 0)
173 			tmp = -EINVAL;
174 		return tmp;
175 	}
176 	for (i = tmp = 0; i < 6; i++, tmp += 2)
177 		dev->net->dev_addr [i] =
178 			(hex_to_bin(buf[tmp]) << 4) + hex_to_bin(buf[tmp + 1]);
179 	return 0;
180 }
181 EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
182 
183 static void intr_complete (struct urb *urb)
184 {
185 	struct usbnet	*dev = urb->context;
186 	int		status = urb->status;
187 
188 	switch (status) {
189 	/* success */
190 	case 0:
191 		dev->driver_info->status(dev, urb);
192 		break;
193 
194 	/* software-driven interface shutdown */
195 	case -ENOENT:		/* urb killed */
196 	case -ESHUTDOWN:	/* hardware gone */
197 		netif_dbg(dev, ifdown, dev->net,
198 			  "intr shutdown, code %d\n", status);
199 		return;
200 
201 	/* NOTE:  not throttling like RX/TX, since this endpoint
202 	 * already polls infrequently
203 	 */
204 	default:
205 		netdev_dbg(dev->net, "intr status %d\n", status);
206 		break;
207 	}
208 
209 	if (!netif_running (dev->net))
210 		return;
211 
212 	status = usb_submit_urb (urb, GFP_ATOMIC);
213 	if (status != 0)
214 		netif_err(dev, timer, dev->net,
215 			  "intr resubmit --> %d\n", status);
216 }
217 
218 static int init_status (struct usbnet *dev, struct usb_interface *intf)
219 {
220 	char		*buf = NULL;
221 	unsigned	pipe = 0;
222 	unsigned	maxp;
223 	unsigned	period;
224 
225 	if (!dev->driver_info->status)
226 		return 0;
227 
228 	pipe = usb_rcvintpipe (dev->udev,
229 			dev->status->desc.bEndpointAddress
230 				& USB_ENDPOINT_NUMBER_MASK);
231 	maxp = usb_maxpacket (dev->udev, pipe, 0);
232 
233 	/* avoid 1 msec chatter:  min 8 msec poll rate */
234 	period = max ((int) dev->status->desc.bInterval,
235 		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
236 
237 	buf = kmalloc (maxp, GFP_KERNEL);
238 	if (buf) {
239 		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
240 		if (!dev->interrupt) {
241 			kfree (buf);
242 			return -ENOMEM;
243 		} else {
244 			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
245 				buf, maxp, intr_complete, dev, period);
246 			dev->interrupt->transfer_flags |= URB_FREE_BUFFER;
247 			dev_dbg(&intf->dev,
248 				"status ep%din, %d bytes period %d\n",
249 				usb_pipeendpoint(pipe), maxp, period);
250 		}
251 	}
252 	return 0;
253 }
254 
255 /* Passes this packet up the stack, updating its accounting.
256  * Some link protocols batch packets, so their rx_fixup paths
257  * can return clones as well as just modify the original skb.
258  */
259 void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
260 {
261 	int	status;
262 
263 	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
264 		skb_queue_tail(&dev->rxq_pause, skb);
265 		return;
266 	}
267 
268 	skb->protocol = eth_type_trans (skb, dev->net);
269 	dev->net->stats.rx_packets++;
270 	dev->net->stats.rx_bytes += skb->len;
271 
272 	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
273 		  skb->len + sizeof (struct ethhdr), skb->protocol);
274 	memset (skb->cb, 0, sizeof (struct skb_data));
275 
276 	if (skb_defer_rx_timestamp(skb))
277 		return;
278 
279 	status = netif_rx (skb);
280 	if (status != NET_RX_SUCCESS)
281 		netif_dbg(dev, rx_err, dev->net,
282 			  "netif_rx status %d\n", status);
283 }
284 EXPORT_SYMBOL_GPL(usbnet_skb_return);
285 
286 
287 /*-------------------------------------------------------------------------
288  *
289  * Network Device Driver (peer link to "Host Device", from USB host)
290  *
291  *-------------------------------------------------------------------------*/
292 
293 int usbnet_change_mtu (struct net_device *net, int new_mtu)
294 {
295 	struct usbnet	*dev = netdev_priv(net);
296 	int		ll_mtu = new_mtu + net->hard_header_len;
297 	int		old_hard_mtu = dev->hard_mtu;
298 	int		old_rx_urb_size = dev->rx_urb_size;
299 
300 	if (new_mtu <= 0)
301 		return -EINVAL;
302 	// no second zero-length packet read wanted after mtu-sized packets
303 	if ((ll_mtu % dev->maxpacket) == 0)
304 		return -EDOM;
305 	net->mtu = new_mtu;
306 
307 	dev->hard_mtu = net->mtu + net->hard_header_len;
308 	if (dev->rx_urb_size == old_hard_mtu) {
309 		dev->rx_urb_size = dev->hard_mtu;
310 		if (dev->rx_urb_size > old_rx_urb_size)
311 			usbnet_unlink_rx_urbs(dev);
312 	}
313 
314 	return 0;
315 }
316 EXPORT_SYMBOL_GPL(usbnet_change_mtu);
317 
318 /* The caller must hold list->lock */
319 static void __usbnet_queue_skb(struct sk_buff_head *list,
320 			struct sk_buff *newsk, enum skb_state state)
321 {
322 	struct skb_data *entry = (struct skb_data *) newsk->cb;
323 
324 	__skb_queue_tail(list, newsk);
325 	entry->state = state;
326 }
327 
328 /*-------------------------------------------------------------------------*/
329 
330 /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
331  * completion callbacks.  2.5 should have fixed those bugs...
332  */
333 
334 static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
335 		struct sk_buff_head *list, enum skb_state state)
336 {
337 	unsigned long		flags;
338 	enum skb_state 		old_state;
339 	struct skb_data *entry = (struct skb_data *) skb->cb;
340 
341 	spin_lock_irqsave(&list->lock, flags);
342 	old_state = entry->state;
343 	entry->state = state;
344 	__skb_unlink(skb, list);
345 	spin_unlock(&list->lock);
346 	spin_lock(&dev->done.lock);
347 	__skb_queue_tail(&dev->done, skb);
348 	if (dev->done.qlen == 1)
349 		tasklet_schedule(&dev->bh);
350 	spin_unlock_irqrestore(&dev->done.lock, flags);
351 	return old_state;
352 }
353 
354 /* some work can't be done in tasklets, so we use keventd
355  *
356  * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
357  * but tasklet_schedule() doesn't.  hope the failure is rare.
358  */
359 void usbnet_defer_kevent (struct usbnet *dev, int work)
360 {
361 	set_bit (work, &dev->flags);
362 	if (!schedule_work (&dev->kevent)) {
363 		if (net_ratelimit())
364 			netdev_err(dev->net, "kevent %d may have been dropped\n", work);
365 	} else {
366 		netdev_dbg(dev->net, "kevent %d scheduled\n", work);
367 	}
368 }
369 EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
370 
371 /*-------------------------------------------------------------------------*/
372 
373 static void rx_complete (struct urb *urb);
374 
375 static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
376 {
377 	struct sk_buff		*skb;
378 	struct skb_data		*entry;
379 	int			retval = 0;
380 	unsigned long		lockflags;
381 	size_t			size = dev->rx_urb_size;
382 
383 	/* prevent rx skb allocation when error ratio is high */
384 	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
385 		usb_free_urb(urb);
386 		return -ENOLINK;
387 	}
388 
389 	skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
390 	if (!skb) {
391 		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
392 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
393 		usb_free_urb (urb);
394 		return -ENOMEM;
395 	}
396 
397 	entry = (struct skb_data *) skb->cb;
398 	entry->urb = urb;
399 	entry->dev = dev;
400 	entry->length = 0;
401 
402 	usb_fill_bulk_urb (urb, dev->udev, dev->in,
403 		skb->data, size, rx_complete, skb);
404 
405 	spin_lock_irqsave (&dev->rxq.lock, lockflags);
406 
407 	if (netif_running (dev->net) &&
408 	    netif_device_present (dev->net) &&
409 	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
410 	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
411 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
412 		case -EPIPE:
413 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
414 			break;
415 		case -ENOMEM:
416 			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
417 			break;
418 		case -ENODEV:
419 			netif_dbg(dev, ifdown, dev->net, "device gone\n");
420 			netif_device_detach (dev->net);
421 			break;
422 		case -EHOSTUNREACH:
423 			retval = -ENOLINK;
424 			break;
425 		default:
426 			netif_dbg(dev, rx_err, dev->net,
427 				  "rx submit, %d\n", retval);
428 			tasklet_schedule (&dev->bh);
429 			break;
430 		case 0:
431 			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
432 		}
433 	} else {
434 		netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
435 		retval = -ENOLINK;
436 	}
437 	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
438 	if (retval) {
439 		dev_kfree_skb_any (skb);
440 		usb_free_urb (urb);
441 	}
442 	return retval;
443 }
444 
445 
446 /*-------------------------------------------------------------------------*/
447 
448 static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
449 {
450 	if (dev->driver_info->rx_fixup &&
451 	    !dev->driver_info->rx_fixup (dev, skb)) {
452 		/* With RX_ASSEMBLE, rx_fixup() must update counters */
453 		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
454 			dev->net->stats.rx_errors++;
455 		goto done;
456 	}
457 	// else network stack removes extra byte if we forced a short packet
458 
459 	if (skb->len) {
460 		/* all data was already cloned from skb inside the driver */
461 		if (dev->driver_info->flags & FLAG_MULTI_PACKET)
462 			dev_kfree_skb_any(skb);
463 		else
464 			usbnet_skb_return(dev, skb);
465 		return;
466 	}
467 
468 	netif_dbg(dev, rx_err, dev->net, "drop\n");
469 	dev->net->stats.rx_errors++;
470 done:
471 	skb_queue_tail(&dev->done, skb);
472 }
473 
474 /*-------------------------------------------------------------------------*/
475 
476 static void rx_complete (struct urb *urb)
477 {
478 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
479 	struct skb_data		*entry = (struct skb_data *) skb->cb;
480 	struct usbnet		*dev = entry->dev;
481 	int			urb_status = urb->status;
482 	enum skb_state		state;
483 
484 	skb_put (skb, urb->actual_length);
485 	state = rx_done;
486 	entry->urb = NULL;
487 
488 	switch (urb_status) {
489 	/* success */
490 	case 0:
491 		if (skb->len < dev->net->hard_header_len) {
492 			state = rx_cleanup;
493 			dev->net->stats.rx_errors++;
494 			dev->net->stats.rx_length_errors++;
495 			netif_dbg(dev, rx_err, dev->net,
496 				  "rx length %d\n", skb->len);
497 		}
498 		break;
499 
500 	/* stalls need manual reset. this is rare ... except that
501 	 * when going through USB 2.0 TTs, unplug appears this way.
502 	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
503 	 * storm, recovering as needed.
504 	 */
505 	case -EPIPE:
506 		dev->net->stats.rx_errors++;
507 		usbnet_defer_kevent (dev, EVENT_RX_HALT);
508 		// FALLTHROUGH
509 
510 	/* software-driven interface shutdown */
511 	case -ECONNRESET:		/* async unlink */
512 	case -ESHUTDOWN:		/* hardware gone */
513 		netif_dbg(dev, ifdown, dev->net,
514 			  "rx shutdown, code %d\n", urb_status);
515 		goto block;
516 
517 	/* we get controller i/o faults during khubd disconnect() delays.
518 	 * throttle down resubmits, to avoid log floods; just temporarily,
519 	 * so we still recover when the fault isn't a khubd delay.
520 	 */
521 	case -EPROTO:
522 	case -ETIME:
523 	case -EILSEQ:
524 		dev->net->stats.rx_errors++;
525 		if (!timer_pending (&dev->delay)) {
526 			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
527 			netif_dbg(dev, link, dev->net,
528 				  "rx throttle %d\n", urb_status);
529 		}
530 block:
531 		state = rx_cleanup;
532 		entry->urb = urb;
533 		urb = NULL;
534 		break;
535 
536 	/* data overrun ... flush fifo? */
537 	case -EOVERFLOW:
538 		dev->net->stats.rx_over_errors++;
539 		// FALLTHROUGH
540 
541 	default:
542 		state = rx_cleanup;
543 		dev->net->stats.rx_errors++;
544 		netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
545 		break;
546 	}
547 
548 	/* stop rx if packet error rate is high */
549 	if (++dev->pkt_cnt > 30) {
550 		dev->pkt_cnt = 0;
551 		dev->pkt_err = 0;
552 	} else {
553 		if (state == rx_cleanup)
554 			dev->pkt_err++;
555 		if (dev->pkt_err > 20)
556 			set_bit(EVENT_RX_KILL, &dev->flags);
557 	}
558 
559 	state = defer_bh(dev, skb, &dev->rxq, state);
560 
561 	if (urb) {
562 		if (netif_running (dev->net) &&
563 		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
564 		    state != unlink_start) {
565 			rx_submit (dev, urb, GFP_ATOMIC);
566 			usb_mark_last_busy(dev->udev);
567 			return;
568 		}
569 		usb_free_urb (urb);
570 	}
571 	netif_dbg(dev, rx_err, dev->net, "no read resubmitted\n");
572 }
573 
574 /*-------------------------------------------------------------------------*/
575 void usbnet_pause_rx(struct usbnet *dev)
576 {
577 	set_bit(EVENT_RX_PAUSED, &dev->flags);
578 
579 	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled\n");
580 }
581 EXPORT_SYMBOL_GPL(usbnet_pause_rx);
582 
583 void usbnet_resume_rx(struct usbnet *dev)
584 {
585 	struct sk_buff *skb;
586 	int num = 0;
587 
588 	clear_bit(EVENT_RX_PAUSED, &dev->flags);
589 
590 	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
591 		usbnet_skb_return(dev, skb);
592 		num++;
593 	}
594 
595 	tasklet_schedule(&dev->bh);
596 
597 	netif_dbg(dev, rx_status, dev->net,
598 		  "paused rx queue disabled, %d skbs requeued\n", num);
599 }
600 EXPORT_SYMBOL_GPL(usbnet_resume_rx);
601 
602 void usbnet_purge_paused_rxq(struct usbnet *dev)
603 {
604 	skb_queue_purge(&dev->rxq_pause);
605 }
606 EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
607 
608 /*-------------------------------------------------------------------------*/
609 
610 // unlink pending rx/tx; completion handlers do all other cleanup
611 
612 static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
613 {
614 	unsigned long		flags;
615 	struct sk_buff		*skb;
616 	int			count = 0;
617 
618 	spin_lock_irqsave (&q->lock, flags);
619 	while (!skb_queue_empty(q)) {
620 		struct skb_data		*entry;
621 		struct urb		*urb;
622 		int			retval;
623 
624 		skb_queue_walk(q, skb) {
625 			entry = (struct skb_data *) skb->cb;
626 			if (entry->state != unlink_start)
627 				goto found;
628 		}
629 		break;
630 found:
631 		entry->state = unlink_start;
632 		urb = entry->urb;
633 
634 		/*
635 		 * Get reference count of the URB to avoid it to be
636 		 * freed during usb_unlink_urb, which may trigger
637 		 * use-after-free problem inside usb_unlink_urb since
638 		 * usb_unlink_urb is always racing with .complete
639 		 * handler(include defer_bh).
640 		 */
641 		usb_get_urb(urb);
642 		spin_unlock_irqrestore(&q->lock, flags);
643 		// during some PM-driven resume scenarios,
644 		// these (async) unlinks complete immediately
645 		retval = usb_unlink_urb (urb);
646 		if (retval != -EINPROGRESS && retval != 0)
647 			netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
648 		else
649 			count++;
650 		usb_put_urb(urb);
651 		spin_lock_irqsave(&q->lock, flags);
652 	}
653 	spin_unlock_irqrestore (&q->lock, flags);
654 	return count;
655 }
656 
657 // Flush all pending rx urbs
658 // minidrivers may need to do this when the MTU changes
659 
660 void usbnet_unlink_rx_urbs(struct usbnet *dev)
661 {
662 	if (netif_running(dev->net)) {
663 		(void) unlink_urbs (dev, &dev->rxq);
664 		tasklet_schedule(&dev->bh);
665 	}
666 }
667 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
668 
669 /*-------------------------------------------------------------------------*/
670 
671 // precondition: never called in_interrupt
672 static void usbnet_terminate_urbs(struct usbnet *dev)
673 {
674 	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(unlink_wakeup);
675 	DECLARE_WAITQUEUE(wait, current);
676 	int temp;
677 
678 	/* ensure there are no more active urbs */
679 	add_wait_queue(&unlink_wakeup, &wait);
680 	set_current_state(TASK_UNINTERRUPTIBLE);
681 	dev->wait = &unlink_wakeup;
682 	temp = unlink_urbs(dev, &dev->txq) +
683 		unlink_urbs(dev, &dev->rxq);
684 
685 	/* maybe wait for deletions to finish. */
686 	while (!skb_queue_empty(&dev->rxq)
687 		&& !skb_queue_empty(&dev->txq)
688 		&& !skb_queue_empty(&dev->done)) {
689 			schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
690 			set_current_state(TASK_UNINTERRUPTIBLE);
691 			netif_dbg(dev, ifdown, dev->net,
692 				  "waited for %d urb completions\n", temp);
693 	}
694 	set_current_state(TASK_RUNNING);
695 	dev->wait = NULL;
696 	remove_wait_queue(&unlink_wakeup, &wait);
697 }
698 
699 int usbnet_stop (struct net_device *net)
700 {
701 	struct usbnet		*dev = netdev_priv(net);
702 	struct driver_info	*info = dev->driver_info;
703 	int			retval;
704 
705 	clear_bit(EVENT_DEV_OPEN, &dev->flags);
706 	netif_stop_queue (net);
707 
708 	netif_info(dev, ifdown, dev->net,
709 		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu\n",
710 		   net->stats.rx_packets, net->stats.tx_packets,
711 		   net->stats.rx_errors, net->stats.tx_errors);
712 
713 	/* allow minidriver to stop correctly (wireless devices to turn off
714 	 * radio etc) */
715 	if (info->stop) {
716 		retval = info->stop(dev);
717 		if (retval < 0)
718 			netif_info(dev, ifdown, dev->net,
719 				   "stop fail (%d) usbnet usb-%s-%s, %s\n",
720 				   retval,
721 				   dev->udev->bus->bus_name, dev->udev->devpath,
722 				   info->description);
723 	}
724 
725 	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
726 		usbnet_terminate_urbs(dev);
727 
728 	usb_kill_urb(dev->interrupt);
729 
730 	usbnet_purge_paused_rxq(dev);
731 
732 	/* deferred work (task, timer, softirq) must also stop.
733 	 * can't flush_scheduled_work() until we drop rtnl (later),
734 	 * else workers could deadlock; so make workers a NOP.
735 	 */
736 	dev->flags = 0;
737 	del_timer_sync (&dev->delay);
738 	tasklet_kill (&dev->bh);
739 	if (info->manage_power &&
740 	    !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))
741 		info->manage_power(dev, 0);
742 	else
743 		usb_autopm_put_interface(dev->intf);
744 
745 	return 0;
746 }
747 EXPORT_SYMBOL_GPL(usbnet_stop);
748 
749 /*-------------------------------------------------------------------------*/
750 
751 // posts reads, and enables write queuing
752 
753 // precondition: never called in_interrupt
754 
755 int usbnet_open (struct net_device *net)
756 {
757 	struct usbnet		*dev = netdev_priv(net);
758 	int			retval;
759 	struct driver_info	*info = dev->driver_info;
760 
761 	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
762 		netif_info(dev, ifup, dev->net,
763 			   "resumption fail (%d) usbnet usb-%s-%s, %s\n",
764 			   retval,
765 			   dev->udev->bus->bus_name,
766 			   dev->udev->devpath,
767 			   info->description);
768 		goto done_nopm;
769 	}
770 
771 	// put into "known safe" state
772 	if (info->reset && (retval = info->reset (dev)) < 0) {
773 		netif_info(dev, ifup, dev->net,
774 			   "open reset fail (%d) usbnet usb-%s-%s, %s\n",
775 			   retval,
776 			   dev->udev->bus->bus_name,
777 			   dev->udev->devpath,
778 			   info->description);
779 		goto done;
780 	}
781 
782 	// insist peer be connected
783 	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
784 		netif_dbg(dev, ifup, dev->net, "can't open; %d\n", retval);
785 		goto done;
786 	}
787 
788 	/* start any status interrupt transfer */
789 	if (dev->interrupt) {
790 		retval = usb_submit_urb (dev->interrupt, GFP_KERNEL);
791 		if (retval < 0) {
792 			netif_err(dev, ifup, dev->net,
793 				  "intr submit %d\n", retval);
794 			goto done;
795 		}
796 	}
797 
798 	set_bit(EVENT_DEV_OPEN, &dev->flags);
799 	netif_start_queue (net);
800 	netif_info(dev, ifup, dev->net,
801 		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing\n",
802 		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
803 		   dev->net->mtu,
804 		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
805 		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
806 		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
807 		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
808 		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
809 		   "simple");
810 
811 	/* reset rx error state */
812 	dev->pkt_cnt = 0;
813 	dev->pkt_err = 0;
814 	clear_bit(EVENT_RX_KILL, &dev->flags);
815 
816 	// delay posting reads until we're fully open
817 	tasklet_schedule (&dev->bh);
818 	if (info->manage_power) {
819 		retval = info->manage_power(dev, 1);
820 		if (retval < 0) {
821 			retval = 0;
822 			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
823 		} else {
824 			usb_autopm_put_interface(dev->intf);
825 		}
826 	}
827 	return retval;
828 done:
829 	usb_autopm_put_interface(dev->intf);
830 done_nopm:
831 	return retval;
832 }
833 EXPORT_SYMBOL_GPL(usbnet_open);
834 
835 /*-------------------------------------------------------------------------*/
836 
837 /* ethtool methods; minidrivers may need to add some more, but
838  * they'll probably want to use this base set.
839  */
840 
841 int usbnet_get_settings (struct net_device *net, struct ethtool_cmd *cmd)
842 {
843 	struct usbnet *dev = netdev_priv(net);
844 
845 	if (!dev->mii.mdio_read)
846 		return -EOPNOTSUPP;
847 
848 	return mii_ethtool_gset(&dev->mii, cmd);
849 }
850 EXPORT_SYMBOL_GPL(usbnet_get_settings);
851 
852 int usbnet_set_settings (struct net_device *net, struct ethtool_cmd *cmd)
853 {
854 	struct usbnet *dev = netdev_priv(net);
855 	int retval;
856 
857 	if (!dev->mii.mdio_write)
858 		return -EOPNOTSUPP;
859 
860 	retval = mii_ethtool_sset(&dev->mii, cmd);
861 
862 	/* link speed/duplex might have changed */
863 	if (dev->driver_info->link_reset)
864 		dev->driver_info->link_reset(dev);
865 
866 	return retval;
867 
868 }
869 EXPORT_SYMBOL_GPL(usbnet_set_settings);
870 
871 u32 usbnet_get_link (struct net_device *net)
872 {
873 	struct usbnet *dev = netdev_priv(net);
874 
875 	/* If a check_connect is defined, return its result */
876 	if (dev->driver_info->check_connect)
877 		return dev->driver_info->check_connect (dev) == 0;
878 
879 	/* if the device has mii operations, use those */
880 	if (dev->mii.mdio_read)
881 		return mii_link_ok(&dev->mii);
882 
883 	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
884 	return ethtool_op_get_link(net);
885 }
886 EXPORT_SYMBOL_GPL(usbnet_get_link);
887 
888 int usbnet_nway_reset(struct net_device *net)
889 {
890 	struct usbnet *dev = netdev_priv(net);
891 
892 	if (!dev->mii.mdio_write)
893 		return -EOPNOTSUPP;
894 
895 	return mii_nway_restart(&dev->mii);
896 }
897 EXPORT_SYMBOL_GPL(usbnet_nway_reset);
898 
899 void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
900 {
901 	struct usbnet *dev = netdev_priv(net);
902 
903 	strlcpy (info->driver, dev->driver_name, sizeof info->driver);
904 	strlcpy (info->version, DRIVER_VERSION, sizeof info->version);
905 	strlcpy (info->fw_version, dev->driver_info->description,
906 		sizeof info->fw_version);
907 	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
908 }
909 EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
910 
911 u32 usbnet_get_msglevel (struct net_device *net)
912 {
913 	struct usbnet *dev = netdev_priv(net);
914 
915 	return dev->msg_enable;
916 }
917 EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
918 
919 void usbnet_set_msglevel (struct net_device *net, u32 level)
920 {
921 	struct usbnet *dev = netdev_priv(net);
922 
923 	dev->msg_enable = level;
924 }
925 EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
926 
927 /* drivers may override default ethtool_ops in their bind() routine */
928 static const struct ethtool_ops usbnet_ethtool_ops = {
929 	.get_settings		= usbnet_get_settings,
930 	.set_settings		= usbnet_set_settings,
931 	.get_link		= usbnet_get_link,
932 	.nway_reset		= usbnet_nway_reset,
933 	.get_drvinfo		= usbnet_get_drvinfo,
934 	.get_msglevel		= usbnet_get_msglevel,
935 	.set_msglevel		= usbnet_set_msglevel,
936 	.get_ts_info		= ethtool_op_get_ts_info,
937 };
938 
939 /*-------------------------------------------------------------------------*/
940 
941 static void __handle_link_change(struct usbnet *dev)
942 {
943 	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
944 		return;
945 
946 	if (!netif_carrier_ok(dev->net)) {
947 		/* kill URBs for reading packets to save bus bandwidth */
948 		unlink_urbs(dev, &dev->rxq);
949 
950 		/*
951 		 * tx_timeout will unlink URBs for sending packets and
952 		 * tx queue is stopped by netcore after link becomes off
953 		 */
954 	} else {
955 		/* submitting URBs for reading packets */
956 		tasklet_schedule(&dev->bh);
957 	}
958 
959 	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
960 }
961 
962 /* work that cannot be done in interrupt context uses keventd.
963  *
964  * NOTE:  with 2.5 we could do more of this using completion callbacks,
965  * especially now that control transfers can be queued.
966  */
967 static void
968 kevent (struct work_struct *work)
969 {
970 	struct usbnet		*dev =
971 		container_of(work, struct usbnet, kevent);
972 	int			status;
973 
974 	/* usb_clear_halt() needs a thread context */
975 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
976 		unlink_urbs (dev, &dev->txq);
977 		status = usb_autopm_get_interface(dev->intf);
978 		if (status < 0)
979 			goto fail_pipe;
980 		status = usb_clear_halt (dev->udev, dev->out);
981 		usb_autopm_put_interface(dev->intf);
982 		if (status < 0 &&
983 		    status != -EPIPE &&
984 		    status != -ESHUTDOWN) {
985 			if (netif_msg_tx_err (dev))
986 fail_pipe:
987 				netdev_err(dev->net, "can't clear tx halt, status %d\n",
988 					   status);
989 		} else {
990 			clear_bit (EVENT_TX_HALT, &dev->flags);
991 			if (status != -ESHUTDOWN)
992 				netif_wake_queue (dev->net);
993 		}
994 	}
995 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
996 		unlink_urbs (dev, &dev->rxq);
997 		status = usb_autopm_get_interface(dev->intf);
998 		if (status < 0)
999 			goto fail_halt;
1000 		status = usb_clear_halt (dev->udev, dev->in);
1001 		usb_autopm_put_interface(dev->intf);
1002 		if (status < 0 &&
1003 		    status != -EPIPE &&
1004 		    status != -ESHUTDOWN) {
1005 			if (netif_msg_rx_err (dev))
1006 fail_halt:
1007 				netdev_err(dev->net, "can't clear rx halt, status %d\n",
1008 					   status);
1009 		} else {
1010 			clear_bit (EVENT_RX_HALT, &dev->flags);
1011 			tasklet_schedule (&dev->bh);
1012 		}
1013 	}
1014 
1015 	/* tasklet could resubmit itself forever if memory is tight */
1016 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
1017 		struct urb	*urb = NULL;
1018 		int resched = 1;
1019 
1020 		if (netif_running (dev->net))
1021 			urb = usb_alloc_urb (0, GFP_KERNEL);
1022 		else
1023 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1024 		if (urb != NULL) {
1025 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1026 			status = usb_autopm_get_interface(dev->intf);
1027 			if (status < 0) {
1028 				usb_free_urb(urb);
1029 				goto fail_lowmem;
1030 			}
1031 			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
1032 				resched = 0;
1033 			usb_autopm_put_interface(dev->intf);
1034 fail_lowmem:
1035 			if (resched)
1036 				tasklet_schedule (&dev->bh);
1037 		}
1038 	}
1039 
1040 	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
1041 		struct driver_info	*info = dev->driver_info;
1042 		int			retval = 0;
1043 
1044 		clear_bit (EVENT_LINK_RESET, &dev->flags);
1045 		status = usb_autopm_get_interface(dev->intf);
1046 		if (status < 0)
1047 			goto skip_reset;
1048 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
1049 			usb_autopm_put_interface(dev->intf);
1050 skip_reset:
1051 			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s\n",
1052 				    retval,
1053 				    dev->udev->bus->bus_name,
1054 				    dev->udev->devpath,
1055 				    info->description);
1056 		} else {
1057 			usb_autopm_put_interface(dev->intf);
1058 		}
1059 
1060 		/* handle link change from link resetting */
1061 		__handle_link_change(dev);
1062 	}
1063 
1064 	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
1065 		__handle_link_change(dev);
1066 
1067 	if (dev->flags)
1068 		netdev_dbg(dev->net, "kevent done, flags = 0x%lx\n", dev->flags);
1069 }
1070 
1071 /*-------------------------------------------------------------------------*/
1072 
1073 static void tx_complete (struct urb *urb)
1074 {
1075 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
1076 	struct skb_data		*entry = (struct skb_data *) skb->cb;
1077 	struct usbnet		*dev = entry->dev;
1078 
1079 	if (urb->status == 0) {
1080 		if (!(dev->driver_info->flags & FLAG_MULTI_PACKET))
1081 			dev->net->stats.tx_packets++;
1082 		dev->net->stats.tx_bytes += entry->length;
1083 	} else {
1084 		dev->net->stats.tx_errors++;
1085 
1086 		switch (urb->status) {
1087 		case -EPIPE:
1088 			usbnet_defer_kevent (dev, EVENT_TX_HALT);
1089 			break;
1090 
1091 		/* software-driven interface shutdown */
1092 		case -ECONNRESET:		// async unlink
1093 		case -ESHUTDOWN:		// hardware gone
1094 			break;
1095 
1096 		// like rx, tx gets controller i/o faults during khubd delays
1097 		// and so it uses the same throttling mechanism.
1098 		case -EPROTO:
1099 		case -ETIME:
1100 		case -EILSEQ:
1101 			usb_mark_last_busy(dev->udev);
1102 			if (!timer_pending (&dev->delay)) {
1103 				mod_timer (&dev->delay,
1104 					jiffies + THROTTLE_JIFFIES);
1105 				netif_dbg(dev, link, dev->net,
1106 					  "tx throttle %d\n", urb->status);
1107 			}
1108 			netif_stop_queue (dev->net);
1109 			break;
1110 		default:
1111 			netif_dbg(dev, tx_err, dev->net,
1112 				  "tx err %d\n", entry->urb->status);
1113 			break;
1114 		}
1115 	}
1116 
1117 	usb_autopm_put_interface_async(dev->intf);
1118 	(void) defer_bh(dev, skb, &dev->txq, tx_done);
1119 }
1120 
1121 /*-------------------------------------------------------------------------*/
1122 
1123 void usbnet_tx_timeout (struct net_device *net)
1124 {
1125 	struct usbnet		*dev = netdev_priv(net);
1126 
1127 	unlink_urbs (dev, &dev->txq);
1128 	tasklet_schedule (&dev->bh);
1129 
1130 	// FIXME: device recovery -- reset?
1131 }
1132 EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
1133 
1134 /*-------------------------------------------------------------------------*/
1135 
1136 netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
1137 				     struct net_device *net)
1138 {
1139 	struct usbnet		*dev = netdev_priv(net);
1140 	int			length;
1141 	struct urb		*urb = NULL;
1142 	struct skb_data		*entry;
1143 	struct driver_info	*info = dev->driver_info;
1144 	unsigned long		flags;
1145 	int retval;
1146 
1147 	if (skb)
1148 		skb_tx_timestamp(skb);
1149 
1150 	// some devices want funky USB-level framing, for
1151 	// win32 driver (usually) and/or hardware quirks
1152 	if (info->tx_fixup) {
1153 		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
1154 		if (!skb) {
1155 			/* packet collected; minidriver waiting for more */
1156 			if (info->flags & FLAG_MULTI_PACKET)
1157 				goto not_drop;
1158 			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
1159 			goto drop;
1160 		}
1161 	}
1162 	length = skb->len;
1163 
1164 	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
1165 		netif_dbg(dev, tx_err, dev->net, "no urb\n");
1166 		goto drop;
1167 	}
1168 
1169 	entry = (struct skb_data *) skb->cb;
1170 	entry->urb = urb;
1171 	entry->dev = dev;
1172 	entry->length = length;
1173 
1174 	usb_fill_bulk_urb (urb, dev->udev, dev->out,
1175 			skb->data, skb->len, tx_complete, skb);
1176 
1177 	/* don't assume the hardware handles USB_ZERO_PACKET
1178 	 * NOTE:  strictly conforming cdc-ether devices should expect
1179 	 * the ZLP here, but ignore the one-byte packet.
1180 	 * NOTE2: CDC NCM specification is different from CDC ECM when
1181 	 * handling ZLP/short packets, so cdc_ncm driver will make short
1182 	 * packet itself if needed.
1183 	 */
1184 	if (length % dev->maxpacket == 0) {
1185 		if (!(info->flags & FLAG_SEND_ZLP)) {
1186 			if (!(info->flags & FLAG_MULTI_PACKET)) {
1187 				urb->transfer_buffer_length++;
1188 				if (skb_tailroom(skb)) {
1189 					skb->data[skb->len] = 0;
1190 					__skb_put(skb, 1);
1191 				}
1192 			}
1193 		} else
1194 			urb->transfer_flags |= URB_ZERO_PACKET;
1195 	}
1196 
1197 	spin_lock_irqsave(&dev->txq.lock, flags);
1198 	retval = usb_autopm_get_interface_async(dev->intf);
1199 	if (retval < 0) {
1200 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1201 		goto drop;
1202 	}
1203 
1204 #ifdef CONFIG_PM
1205 	/* if this triggers the device is still a sleep */
1206 	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
1207 		/* transmission will be done in resume */
1208 		usb_anchor_urb(urb, &dev->deferred);
1209 		/* no use to process more packets */
1210 		netif_stop_queue(net);
1211 		usb_put_urb(urb);
1212 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1213 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
1214 		goto deferred;
1215 	}
1216 #endif
1217 
1218 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
1219 	case -EPIPE:
1220 		netif_stop_queue (net);
1221 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
1222 		usb_autopm_put_interface_async(dev->intf);
1223 		break;
1224 	default:
1225 		usb_autopm_put_interface_async(dev->intf);
1226 		netif_dbg(dev, tx_err, dev->net,
1227 			  "tx: submit urb err %d\n", retval);
1228 		break;
1229 	case 0:
1230 		net->trans_start = jiffies;
1231 		__usbnet_queue_skb(&dev->txq, skb, tx_start);
1232 		if (dev->txq.qlen >= TX_QLEN (dev))
1233 			netif_stop_queue (net);
1234 	}
1235 	spin_unlock_irqrestore (&dev->txq.lock, flags);
1236 
1237 	if (retval) {
1238 		netif_dbg(dev, tx_err, dev->net, "drop, code %d\n", retval);
1239 drop:
1240 		dev->net->stats.tx_dropped++;
1241 not_drop:
1242 		if (skb)
1243 			dev_kfree_skb_any (skb);
1244 		usb_free_urb (urb);
1245 	} else
1246 		netif_dbg(dev, tx_queued, dev->net,
1247 			  "> tx, len %d, type 0x%x\n", length, skb->protocol);
1248 #ifdef CONFIG_PM
1249 deferred:
1250 #endif
1251 	return NETDEV_TX_OK;
1252 }
1253 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
1254 
1255 static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
1256 {
1257 	struct urb	*urb;
1258 	int		i;
1259 	int		ret = 0;
1260 
1261 	/* don't refill the queue all at once */
1262 	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
1263 		urb = usb_alloc_urb(0, flags);
1264 		if (urb != NULL) {
1265 			ret = rx_submit(dev, urb, flags);
1266 			if (ret)
1267 				goto err;
1268 		} else {
1269 			ret = -ENOMEM;
1270 			goto err;
1271 		}
1272 	}
1273 err:
1274 	return ret;
1275 }
1276 
1277 /*-------------------------------------------------------------------------*/
1278 
1279 // tasklet (work deferred from completions, in_irq) or timer
1280 
1281 static void usbnet_bh (unsigned long param)
1282 {
1283 	struct usbnet		*dev = (struct usbnet *) param;
1284 	struct sk_buff		*skb;
1285 	struct skb_data		*entry;
1286 
1287 	while ((skb = skb_dequeue (&dev->done))) {
1288 		entry = (struct skb_data *) skb->cb;
1289 		switch (entry->state) {
1290 		case rx_done:
1291 			entry->state = rx_cleanup;
1292 			rx_process (dev, skb);
1293 			continue;
1294 		case tx_done:
1295 		case rx_cleanup:
1296 			usb_free_urb (entry->urb);
1297 			dev_kfree_skb (skb);
1298 			continue;
1299 		default:
1300 			netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
1301 		}
1302 	}
1303 
1304 	/* restart RX again after disabling due to high error rate */
1305 	clear_bit(EVENT_RX_KILL, &dev->flags);
1306 
1307 	// waiting for all pending urbs to complete?
1308 	if (dev->wait) {
1309 		if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
1310 			wake_up (dev->wait);
1311 		}
1312 
1313 	// or are we maybe short a few urbs?
1314 	} else if (netif_running (dev->net) &&
1315 		   netif_device_present (dev->net) &&
1316 		   netif_carrier_ok(dev->net) &&
1317 		   !timer_pending (&dev->delay) &&
1318 		   !test_bit (EVENT_RX_HALT, &dev->flags)) {
1319 		int	temp = dev->rxq.qlen;
1320 
1321 		if (temp < RX_QLEN(dev)) {
1322 			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
1323 				return;
1324 			if (temp != dev->rxq.qlen)
1325 				netif_dbg(dev, link, dev->net,
1326 					  "rxqlen %d --> %d\n",
1327 					  temp, dev->rxq.qlen);
1328 			if (dev->rxq.qlen < RX_QLEN(dev))
1329 				tasklet_schedule (&dev->bh);
1330 		}
1331 		if (dev->txq.qlen < TX_QLEN (dev))
1332 			netif_wake_queue (dev->net);
1333 	}
1334 }
1335 
1336 
1337 /*-------------------------------------------------------------------------
1338  *
1339  * USB Device Driver support
1340  *
1341  *-------------------------------------------------------------------------*/
1342 
1343 // precondition: never called in_interrupt
1344 
1345 void usbnet_disconnect (struct usb_interface *intf)
1346 {
1347 	struct usbnet		*dev;
1348 	struct usb_device	*xdev;
1349 	struct net_device	*net;
1350 
1351 	dev = usb_get_intfdata(intf);
1352 	usb_set_intfdata(intf, NULL);
1353 	if (!dev)
1354 		return;
1355 
1356 	xdev = interface_to_usbdev (intf);
1357 
1358 	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s\n",
1359 		   intf->dev.driver->name,
1360 		   xdev->bus->bus_name, xdev->devpath,
1361 		   dev->driver_info->description);
1362 
1363 	net = dev->net;
1364 	unregister_netdev (net);
1365 
1366 	cancel_work_sync(&dev->kevent);
1367 
1368 	usb_scuttle_anchored_urbs(&dev->deferred);
1369 
1370 	if (dev->driver_info->unbind)
1371 		dev->driver_info->unbind (dev, intf);
1372 
1373 	usb_kill_urb(dev->interrupt);
1374 	usb_free_urb(dev->interrupt);
1375 
1376 	free_netdev(net);
1377 }
1378 EXPORT_SYMBOL_GPL(usbnet_disconnect);
1379 
1380 static const struct net_device_ops usbnet_netdev_ops = {
1381 	.ndo_open		= usbnet_open,
1382 	.ndo_stop		= usbnet_stop,
1383 	.ndo_start_xmit		= usbnet_start_xmit,
1384 	.ndo_tx_timeout		= usbnet_tx_timeout,
1385 	.ndo_change_mtu		= usbnet_change_mtu,
1386 	.ndo_set_mac_address 	= eth_mac_addr,
1387 	.ndo_validate_addr	= eth_validate_addr,
1388 };
1389 
1390 /*-------------------------------------------------------------------------*/
1391 
1392 // precondition: never called in_interrupt
1393 
1394 static struct device_type wlan_type = {
1395 	.name	= "wlan",
1396 };
1397 
1398 static struct device_type wwan_type = {
1399 	.name	= "wwan",
1400 };
1401 
1402 int
1403 usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
1404 {
1405 	struct usbnet			*dev;
1406 	struct net_device		*net;
1407 	struct usb_host_interface	*interface;
1408 	struct driver_info		*info;
1409 	struct usb_device		*xdev;
1410 	int				status;
1411 	const char			*name;
1412 	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
1413 
1414 	/* usbnet already took usb runtime pm, so have to enable the feature
1415 	 * for usb interface, otherwise usb_autopm_get_interface may return
1416 	 * failure if USB_SUSPEND(RUNTIME_PM) is enabled.
1417 	 */
1418 	if (!driver->supports_autosuspend) {
1419 		driver->supports_autosuspend = 1;
1420 		pm_runtime_enable(&udev->dev);
1421 	}
1422 
1423 	name = udev->dev.driver->name;
1424 	info = (struct driver_info *) prod->driver_info;
1425 	if (!info) {
1426 		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
1427 		return -ENODEV;
1428 	}
1429 	xdev = interface_to_usbdev (udev);
1430 	interface = udev->cur_altsetting;
1431 
1432 	status = -ENOMEM;
1433 
1434 	// set up our own records
1435 	net = alloc_etherdev(sizeof(*dev));
1436 	if (!net)
1437 		goto out;
1438 
1439 	/* netdev_printk() needs this so do it as early as possible */
1440 	SET_NETDEV_DEV(net, &udev->dev);
1441 
1442 	dev = netdev_priv(net);
1443 	dev->udev = xdev;
1444 	dev->intf = udev;
1445 	dev->driver_info = info;
1446 	dev->driver_name = name;
1447 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
1448 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
1449 	skb_queue_head_init (&dev->rxq);
1450 	skb_queue_head_init (&dev->txq);
1451 	skb_queue_head_init (&dev->done);
1452 	skb_queue_head_init(&dev->rxq_pause);
1453 	dev->bh.func = usbnet_bh;
1454 	dev->bh.data = (unsigned long) dev;
1455 	INIT_WORK (&dev->kevent, kevent);
1456 	init_usb_anchor(&dev->deferred);
1457 	dev->delay.function = usbnet_bh;
1458 	dev->delay.data = (unsigned long) dev;
1459 	init_timer (&dev->delay);
1460 	mutex_init (&dev->phy_mutex);
1461 
1462 	dev->net = net;
1463 	strcpy (net->name, "usb%d");
1464 	memcpy (net->dev_addr, node_id, sizeof node_id);
1465 
1466 	/* rx and tx sides can use different message sizes;
1467 	 * bind() should set rx_urb_size in that case.
1468 	 */
1469 	dev->hard_mtu = net->mtu + net->hard_header_len;
1470 #if 0
1471 // dma_supported() is deeply broken on almost all architectures
1472 	// possible with some EHCI controllers
1473 	if (dma_supported (&udev->dev, DMA_BIT_MASK(64)))
1474 		net->features |= NETIF_F_HIGHDMA;
1475 #endif
1476 
1477 	net->netdev_ops = &usbnet_netdev_ops;
1478 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
1479 	net->ethtool_ops = &usbnet_ethtool_ops;
1480 
1481 	// allow device-specific bind/init procedures
1482 	// NOTE net->name still not usable ...
1483 	if (info->bind) {
1484 		status = info->bind (dev, udev);
1485 		if (status < 0)
1486 			goto out1;
1487 
1488 		// heuristic:  "usb%d" for links we know are two-host,
1489 		// else "eth%d" when there's reasonable doubt.  userspace
1490 		// can rename the link if it knows better.
1491 		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
1492 		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
1493 		     (net->dev_addr [0] & 0x02) == 0))
1494 			strcpy (net->name, "eth%d");
1495 		/* WLAN devices should always be named "wlan%d" */
1496 		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1497 			strcpy(net->name, "wlan%d");
1498 		/* WWAN devices should always be named "wwan%d" */
1499 		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1500 			strcpy(net->name, "wwan%d");
1501 
1502 		/* devices that cannot do ARP */
1503 		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
1504 			net->flags |= IFF_NOARP;
1505 
1506 		/* maybe the remote can't receive an Ethernet MTU */
1507 		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
1508 			net->mtu = dev->hard_mtu - net->hard_header_len;
1509 	} else if (!info->in || !info->out)
1510 		status = usbnet_get_endpoints (dev, udev);
1511 	else {
1512 		dev->in = usb_rcvbulkpipe (xdev, info->in);
1513 		dev->out = usb_sndbulkpipe (xdev, info->out);
1514 		if (!(info->flags & FLAG_NO_SETINT))
1515 			status = usb_set_interface (xdev,
1516 				interface->desc.bInterfaceNumber,
1517 				interface->desc.bAlternateSetting);
1518 		else
1519 			status = 0;
1520 
1521 	}
1522 	if (status >= 0 && dev->status)
1523 		status = init_status (dev, udev);
1524 	if (status < 0)
1525 		goto out3;
1526 
1527 	if (!dev->rx_urb_size)
1528 		dev->rx_urb_size = dev->hard_mtu;
1529 	dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
1530 
1531 	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1532 		SET_NETDEV_DEVTYPE(net, &wlan_type);
1533 	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1534 		SET_NETDEV_DEVTYPE(net, &wwan_type);
1535 
1536 	status = register_netdev (net);
1537 	if (status)
1538 		goto out4;
1539 	netif_info(dev, probe, dev->net,
1540 		   "register '%s' at usb-%s-%s, %s, %pM\n",
1541 		   udev->dev.driver->name,
1542 		   xdev->bus->bus_name, xdev->devpath,
1543 		   dev->driver_info->description,
1544 		   net->dev_addr);
1545 
1546 	// ok, it's ready to go.
1547 	usb_set_intfdata (udev, dev);
1548 
1549 	netif_device_attach (net);
1550 
1551 	if (dev->driver_info->flags & FLAG_LINK_INTR)
1552 		usbnet_link_change(dev, 0, 0);
1553 
1554 	return 0;
1555 
1556 out4:
1557 	usb_free_urb(dev->interrupt);
1558 out3:
1559 	if (info->unbind)
1560 		info->unbind (dev, udev);
1561 out1:
1562 	free_netdev(net);
1563 out:
1564 	return status;
1565 }
1566 EXPORT_SYMBOL_GPL(usbnet_probe);
1567 
1568 /*-------------------------------------------------------------------------*/
1569 
1570 /*
1571  * suspend the whole driver as soon as the first interface is suspended
1572  * resume only when the last interface is resumed
1573  */
1574 
1575 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
1576 {
1577 	struct usbnet		*dev = usb_get_intfdata(intf);
1578 
1579 	if (!dev->suspend_count++) {
1580 		spin_lock_irq(&dev->txq.lock);
1581 		/* don't autosuspend while transmitting */
1582 		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
1583 			dev->suspend_count--;
1584 			spin_unlock_irq(&dev->txq.lock);
1585 			return -EBUSY;
1586 		} else {
1587 			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
1588 			spin_unlock_irq(&dev->txq.lock);
1589 		}
1590 		/*
1591 		 * accelerate emptying of the rx and queues, to avoid
1592 		 * having everything error out.
1593 		 */
1594 		netif_device_detach (dev->net);
1595 		usbnet_terminate_urbs(dev);
1596 		usb_kill_urb(dev->interrupt);
1597 
1598 		/*
1599 		 * reattach so runtime management can use and
1600 		 * wake the device
1601 		 */
1602 		netif_device_attach (dev->net);
1603 	}
1604 	return 0;
1605 }
1606 EXPORT_SYMBOL_GPL(usbnet_suspend);
1607 
1608 int usbnet_resume (struct usb_interface *intf)
1609 {
1610 	struct usbnet		*dev = usb_get_intfdata(intf);
1611 	struct sk_buff          *skb;
1612 	struct urb              *res;
1613 	int                     retval;
1614 
1615 	if (!--dev->suspend_count) {
1616 		/* resume interrupt URBs */
1617 		if (dev->interrupt && test_bit(EVENT_DEV_OPEN, &dev->flags))
1618 			usb_submit_urb(dev->interrupt, GFP_NOIO);
1619 
1620 		spin_lock_irq(&dev->txq.lock);
1621 		while ((res = usb_get_from_anchor(&dev->deferred))) {
1622 
1623 			skb = (struct sk_buff *)res->context;
1624 			retval = usb_submit_urb(res, GFP_ATOMIC);
1625 			if (retval < 0) {
1626 				dev_kfree_skb_any(skb);
1627 				usb_free_urb(res);
1628 				usb_autopm_put_interface_async(dev->intf);
1629 			} else {
1630 				dev->net->trans_start = jiffies;
1631 				__skb_queue_tail(&dev->txq, skb);
1632 			}
1633 		}
1634 
1635 		smp_mb();
1636 		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
1637 		spin_unlock_irq(&dev->txq.lock);
1638 
1639 		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
1640 			/* handle remote wakeup ASAP */
1641 			if (!dev->wait &&
1642 				netif_device_present(dev->net) &&
1643 				!timer_pending(&dev->delay) &&
1644 				!test_bit(EVENT_RX_HALT, &dev->flags))
1645 					rx_alloc_submit(dev, GFP_NOIO);
1646 
1647 			if (!(dev->txq.qlen >= TX_QLEN(dev)))
1648 				netif_tx_wake_all_queues(dev->net);
1649 			tasklet_schedule (&dev->bh);
1650 		}
1651 	}
1652 
1653 	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
1654 		usb_autopm_get_interface_no_resume(intf);
1655 
1656 	return 0;
1657 }
1658 EXPORT_SYMBOL_GPL(usbnet_resume);
1659 
1660 /*
1661  * Either a subdriver implements manage_power, then it is assumed to always
1662  * be ready to be suspended or it reports the readiness to be suspended
1663  * explicitly
1664  */
1665 void usbnet_device_suggests_idle(struct usbnet *dev)
1666 {
1667 	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
1668 		dev->intf->needs_remote_wakeup = 1;
1669 		usb_autopm_put_interface_async(dev->intf);
1670 	}
1671 }
1672 EXPORT_SYMBOL(usbnet_device_suggests_idle);
1673 
1674 /*
1675  * For devices that can do without special commands
1676  */
1677 int usbnet_manage_power(struct usbnet *dev, int on)
1678 {
1679 	dev->intf->needs_remote_wakeup = on;
1680 	return 0;
1681 }
1682 EXPORT_SYMBOL(usbnet_manage_power);
1683 
1684 void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
1685 {
1686 	/* update link after link is reseted */
1687 	if (link && !need_reset)
1688 		netif_carrier_on(dev->net);
1689 	else
1690 		netif_carrier_off(dev->net);
1691 
1692 	if (need_reset && link)
1693 		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
1694 	else
1695 		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
1696 }
1697 EXPORT_SYMBOL(usbnet_link_change);
1698 
1699 /*-------------------------------------------------------------------------*/
1700 static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1701 			     u16 value, u16 index, void *data, u16 size)
1702 {
1703 	void *buf = NULL;
1704 	int err = -ENOMEM;
1705 
1706 	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
1707 		   " value=0x%04x index=0x%04x size=%d\n",
1708 		   cmd, reqtype, value, index, size);
1709 
1710 	if (data) {
1711 		buf = kmalloc(size, GFP_KERNEL);
1712 		if (!buf)
1713 			goto out;
1714 	}
1715 
1716 	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
1717 			      cmd, reqtype, value, index, buf, size,
1718 			      USB_CTRL_GET_TIMEOUT);
1719 	if (err > 0 && err <= size)
1720 		memcpy(data, buf, err);
1721 	kfree(buf);
1722 out:
1723 	return err;
1724 }
1725 
1726 static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1727 			      u16 value, u16 index, const void *data,
1728 			      u16 size)
1729 {
1730 	void *buf = NULL;
1731 	int err = -ENOMEM;
1732 
1733 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
1734 		   " value=0x%04x index=0x%04x size=%d\n",
1735 		   cmd, reqtype, value, index, size);
1736 
1737 	if (data) {
1738 		buf = kmemdup(data, size, GFP_KERNEL);
1739 		if (!buf)
1740 			goto out;
1741 	}
1742 
1743 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
1744 			      cmd, reqtype, value, index, buf, size,
1745 			      USB_CTRL_SET_TIMEOUT);
1746 	kfree(buf);
1747 
1748 out:
1749 	return err;
1750 }
1751 
1752 /*
1753  * The function can't be called inside suspend/resume callback,
1754  * otherwise deadlock will be caused.
1755  */
1756 int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1757 		    u16 value, u16 index, void *data, u16 size)
1758 {
1759 	int ret;
1760 
1761 	if (usb_autopm_get_interface(dev->intf) < 0)
1762 		return -ENODEV;
1763 	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
1764 				data, size);
1765 	usb_autopm_put_interface(dev->intf);
1766 	return ret;
1767 }
1768 EXPORT_SYMBOL_GPL(usbnet_read_cmd);
1769 
1770 /*
1771  * The function can't be called inside suspend/resume callback,
1772  * otherwise deadlock will be caused.
1773  */
1774 int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1775 		     u16 value, u16 index, const void *data, u16 size)
1776 {
1777 	int ret;
1778 
1779 	if (usb_autopm_get_interface(dev->intf) < 0)
1780 		return -ENODEV;
1781 	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
1782 				 data, size);
1783 	usb_autopm_put_interface(dev->intf);
1784 	return ret;
1785 }
1786 EXPORT_SYMBOL_GPL(usbnet_write_cmd);
1787 
1788 /*
1789  * The function can be called inside suspend/resume callback safely
1790  * and should only be called by suspend/resume callback generally.
1791  */
1792 int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
1793 			  u16 value, u16 index, void *data, u16 size)
1794 {
1795 	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
1796 				 data, size);
1797 }
1798 EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
1799 
1800 /*
1801  * The function can be called inside suspend/resume callback safely
1802  * and should only be called by suspend/resume callback generally.
1803  */
1804 int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
1805 			  u16 value, u16 index, const void *data,
1806 			  u16 size)
1807 {
1808 	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
1809 				  data, size);
1810 }
1811 EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
1812 
1813 static void usbnet_async_cmd_cb(struct urb *urb)
1814 {
1815 	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
1816 	int status = urb->status;
1817 
1818 	if (status < 0)
1819 		dev_dbg(&urb->dev->dev, "%s failed with %d",
1820 			__func__, status);
1821 
1822 	kfree(req);
1823 	usb_free_urb(urb);
1824 }
1825 
1826 /*
1827  * The caller must make sure that device can't be put into suspend
1828  * state until the control URB completes.
1829  */
1830 int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
1831 			   u16 value, u16 index, const void *data, u16 size)
1832 {
1833 	struct usb_ctrlrequest *req = NULL;
1834 	struct urb *urb;
1835 	int err = -ENOMEM;
1836 	void *buf = NULL;
1837 
1838 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
1839 		   " value=0x%04x index=0x%04x size=%d\n",
1840 		   cmd, reqtype, value, index, size);
1841 
1842 	urb = usb_alloc_urb(0, GFP_ATOMIC);
1843 	if (!urb) {
1844 		netdev_err(dev->net, "Error allocating URB in"
1845 			   " %s!\n", __func__);
1846 		goto fail;
1847 	}
1848 
1849 	if (data) {
1850 		buf = kmemdup(data, size, GFP_ATOMIC);
1851 		if (!buf) {
1852 			netdev_err(dev->net, "Error allocating buffer"
1853 				   " in %s!\n", __func__);
1854 			goto fail_free;
1855 		}
1856 	}
1857 
1858 	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
1859 	if (!req)
1860 		goto fail_free_buf;
1861 
1862 	req->bRequestType = reqtype;
1863 	req->bRequest = cmd;
1864 	req->wValue = cpu_to_le16(value);
1865 	req->wIndex = cpu_to_le16(index);
1866 	req->wLength = cpu_to_le16(size);
1867 
1868 	usb_fill_control_urb(urb, dev->udev,
1869 			     usb_sndctrlpipe(dev->udev, 0),
1870 			     (void *)req, buf, size,
1871 			     usbnet_async_cmd_cb, req);
1872 	urb->transfer_flags |= URB_FREE_BUFFER;
1873 
1874 	err = usb_submit_urb(urb, GFP_ATOMIC);
1875 	if (err < 0) {
1876 		netdev_err(dev->net, "Error submitting the control"
1877 			   " message: status=%d\n", err);
1878 		goto fail_free;
1879 	}
1880 	return 0;
1881 
1882 fail_free_buf:
1883 	kfree(buf);
1884 fail_free:
1885 	kfree(req);
1886 	usb_free_urb(urb);
1887 fail:
1888 	return err;
1889 
1890 }
1891 EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
1892 /*-------------------------------------------------------------------------*/
1893 
1894 static int __init usbnet_init(void)
1895 {
1896 	/* Compiler should optimize this out. */
1897 	BUILD_BUG_ON(
1898 		FIELD_SIZEOF(struct sk_buff, cb) < sizeof(struct skb_data));
1899 
1900 	eth_random_addr(node_id);
1901 	return 0;
1902 }
1903 module_init(usbnet_init);
1904 
1905 static void __exit usbnet_exit(void)
1906 {
1907 }
1908 module_exit(usbnet_exit);
1909 
1910 MODULE_AUTHOR("David Brownell");
1911 MODULE_DESCRIPTION("USB network driver framework");
1912 MODULE_LICENSE("GPL");
1913