xref: /openbmc/linux/drivers/net/usb/usbnet.c (revision 24b1944f)
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 /* Submit the interrupt URB if not previously submitted, increasing refcount */
256 int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
257 {
258 	int ret = 0;
259 
260 	WARN_ON_ONCE(dev->interrupt == NULL);
261 	if (dev->interrupt) {
262 		mutex_lock(&dev->interrupt_mutex);
263 
264 		if (++dev->interrupt_count == 1)
265 			ret = usb_submit_urb(dev->interrupt, mem_flags);
266 
267 		dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d\n",
268 			dev->interrupt_count);
269 		mutex_unlock(&dev->interrupt_mutex);
270 	}
271 	return ret;
272 }
273 EXPORT_SYMBOL_GPL(usbnet_status_start);
274 
275 /* For resume; submit interrupt URB if previously submitted */
276 static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
277 {
278 	int ret = 0;
279 
280 	mutex_lock(&dev->interrupt_mutex);
281 	if (dev->interrupt_count) {
282 		ret = usb_submit_urb(dev->interrupt, mem_flags);
283 		dev_dbg(&dev->udev->dev,
284 			"submitted interrupt URB for resume\n");
285 	}
286 	mutex_unlock(&dev->interrupt_mutex);
287 	return ret;
288 }
289 
290 /* Kill the interrupt URB if all submitters want it killed */
291 void usbnet_status_stop(struct usbnet *dev)
292 {
293 	if (dev->interrupt) {
294 		mutex_lock(&dev->interrupt_mutex);
295 		WARN_ON(dev->interrupt_count == 0);
296 
297 		if (dev->interrupt_count && --dev->interrupt_count == 0)
298 			usb_kill_urb(dev->interrupt);
299 
300 		dev_dbg(&dev->udev->dev,
301 			"decremented interrupt URB count to %d\n",
302 			dev->interrupt_count);
303 		mutex_unlock(&dev->interrupt_mutex);
304 	}
305 }
306 EXPORT_SYMBOL_GPL(usbnet_status_stop);
307 
308 /* For suspend; always kill interrupt URB */
309 static void __usbnet_status_stop_force(struct usbnet *dev)
310 {
311 	if (dev->interrupt) {
312 		mutex_lock(&dev->interrupt_mutex);
313 		usb_kill_urb(dev->interrupt);
314 		dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend\n");
315 		mutex_unlock(&dev->interrupt_mutex);
316 	}
317 }
318 
319 /* Passes this packet up the stack, updating its accounting.
320  * Some link protocols batch packets, so their rx_fixup paths
321  * can return clones as well as just modify the original skb.
322  */
323 void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
324 {
325 	int	status;
326 
327 	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
328 		skb_queue_tail(&dev->rxq_pause, skb);
329 		return;
330 	}
331 
332 	skb->protocol = eth_type_trans (skb, dev->net);
333 	dev->net->stats.rx_packets++;
334 	dev->net->stats.rx_bytes += skb->len;
335 
336 	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
337 		  skb->len + sizeof (struct ethhdr), skb->protocol);
338 	memset (skb->cb, 0, sizeof (struct skb_data));
339 
340 	if (skb_defer_rx_timestamp(skb))
341 		return;
342 
343 	status = netif_rx (skb);
344 	if (status != NET_RX_SUCCESS)
345 		netif_dbg(dev, rx_err, dev->net,
346 			  "netif_rx status %d\n", status);
347 }
348 EXPORT_SYMBOL_GPL(usbnet_skb_return);
349 
350 
351 /*-------------------------------------------------------------------------
352  *
353  * Network Device Driver (peer link to "Host Device", from USB host)
354  *
355  *-------------------------------------------------------------------------*/
356 
357 int usbnet_change_mtu (struct net_device *net, int new_mtu)
358 {
359 	struct usbnet	*dev = netdev_priv(net);
360 	int		ll_mtu = new_mtu + net->hard_header_len;
361 	int		old_hard_mtu = dev->hard_mtu;
362 	int		old_rx_urb_size = dev->rx_urb_size;
363 
364 	if (new_mtu <= 0)
365 		return -EINVAL;
366 	// no second zero-length packet read wanted after mtu-sized packets
367 	if ((ll_mtu % dev->maxpacket) == 0)
368 		return -EDOM;
369 	net->mtu = new_mtu;
370 
371 	dev->hard_mtu = net->mtu + net->hard_header_len;
372 	if (dev->rx_urb_size == old_hard_mtu) {
373 		dev->rx_urb_size = dev->hard_mtu;
374 		if (dev->rx_urb_size > old_rx_urb_size)
375 			usbnet_unlink_rx_urbs(dev);
376 	}
377 
378 	return 0;
379 }
380 EXPORT_SYMBOL_GPL(usbnet_change_mtu);
381 
382 /* The caller must hold list->lock */
383 static void __usbnet_queue_skb(struct sk_buff_head *list,
384 			struct sk_buff *newsk, enum skb_state state)
385 {
386 	struct skb_data *entry = (struct skb_data *) newsk->cb;
387 
388 	__skb_queue_tail(list, newsk);
389 	entry->state = state;
390 }
391 
392 /*-------------------------------------------------------------------------*/
393 
394 /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
395  * completion callbacks.  2.5 should have fixed those bugs...
396  */
397 
398 static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
399 		struct sk_buff_head *list, enum skb_state state)
400 {
401 	unsigned long		flags;
402 	enum skb_state 		old_state;
403 	struct skb_data *entry = (struct skb_data *) skb->cb;
404 
405 	spin_lock_irqsave(&list->lock, flags);
406 	old_state = entry->state;
407 	entry->state = state;
408 	__skb_unlink(skb, list);
409 	spin_unlock(&list->lock);
410 	spin_lock(&dev->done.lock);
411 	__skb_queue_tail(&dev->done, skb);
412 	if (dev->done.qlen == 1)
413 		tasklet_schedule(&dev->bh);
414 	spin_unlock_irqrestore(&dev->done.lock, flags);
415 	return old_state;
416 }
417 
418 /* some work can't be done in tasklets, so we use keventd
419  *
420  * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
421  * but tasklet_schedule() doesn't.  hope the failure is rare.
422  */
423 void usbnet_defer_kevent (struct usbnet *dev, int work)
424 {
425 	set_bit (work, &dev->flags);
426 	if (!schedule_work (&dev->kevent)) {
427 		if (net_ratelimit())
428 			netdev_err(dev->net, "kevent %d may have been dropped\n", work);
429 	} else {
430 		netdev_dbg(dev->net, "kevent %d scheduled\n", work);
431 	}
432 }
433 EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
434 
435 /*-------------------------------------------------------------------------*/
436 
437 static void rx_complete (struct urb *urb);
438 
439 static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
440 {
441 	struct sk_buff		*skb;
442 	struct skb_data		*entry;
443 	int			retval = 0;
444 	unsigned long		lockflags;
445 	size_t			size = dev->rx_urb_size;
446 
447 	/* prevent rx skb allocation when error ratio is high */
448 	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
449 		usb_free_urb(urb);
450 		return -ENOLINK;
451 	}
452 
453 	skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
454 	if (!skb) {
455 		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
456 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
457 		usb_free_urb (urb);
458 		return -ENOMEM;
459 	}
460 
461 	entry = (struct skb_data *) skb->cb;
462 	entry->urb = urb;
463 	entry->dev = dev;
464 	entry->length = 0;
465 
466 	usb_fill_bulk_urb (urb, dev->udev, dev->in,
467 		skb->data, size, rx_complete, skb);
468 
469 	spin_lock_irqsave (&dev->rxq.lock, lockflags);
470 
471 	if (netif_running (dev->net) &&
472 	    netif_device_present (dev->net) &&
473 	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
474 	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
475 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
476 		case -EPIPE:
477 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
478 			break;
479 		case -ENOMEM:
480 			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
481 			break;
482 		case -ENODEV:
483 			netif_dbg(dev, ifdown, dev->net, "device gone\n");
484 			netif_device_detach (dev->net);
485 			break;
486 		case -EHOSTUNREACH:
487 			retval = -ENOLINK;
488 			break;
489 		default:
490 			netif_dbg(dev, rx_err, dev->net,
491 				  "rx submit, %d\n", retval);
492 			tasklet_schedule (&dev->bh);
493 			break;
494 		case 0:
495 			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
496 		}
497 	} else {
498 		netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
499 		retval = -ENOLINK;
500 	}
501 	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
502 	if (retval) {
503 		dev_kfree_skb_any (skb);
504 		usb_free_urb (urb);
505 	}
506 	return retval;
507 }
508 
509 
510 /*-------------------------------------------------------------------------*/
511 
512 static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
513 {
514 	if (dev->driver_info->rx_fixup &&
515 	    !dev->driver_info->rx_fixup (dev, skb)) {
516 		/* With RX_ASSEMBLE, rx_fixup() must update counters */
517 		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
518 			dev->net->stats.rx_errors++;
519 		goto done;
520 	}
521 	// else network stack removes extra byte if we forced a short packet
522 
523 	if (skb->len) {
524 		/* all data was already cloned from skb inside the driver */
525 		if (dev->driver_info->flags & FLAG_MULTI_PACKET)
526 			dev_kfree_skb_any(skb);
527 		else
528 			usbnet_skb_return(dev, skb);
529 		return;
530 	}
531 
532 	netif_dbg(dev, rx_err, dev->net, "drop\n");
533 	dev->net->stats.rx_errors++;
534 done:
535 	skb_queue_tail(&dev->done, skb);
536 }
537 
538 /*-------------------------------------------------------------------------*/
539 
540 static void rx_complete (struct urb *urb)
541 {
542 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
543 	struct skb_data		*entry = (struct skb_data *) skb->cb;
544 	struct usbnet		*dev = entry->dev;
545 	int			urb_status = urb->status;
546 	enum skb_state		state;
547 
548 	skb_put (skb, urb->actual_length);
549 	state = rx_done;
550 	entry->urb = NULL;
551 
552 	switch (urb_status) {
553 	/* success */
554 	case 0:
555 		if (skb->len < dev->net->hard_header_len) {
556 			state = rx_cleanup;
557 			dev->net->stats.rx_errors++;
558 			dev->net->stats.rx_length_errors++;
559 			netif_dbg(dev, rx_err, dev->net,
560 				  "rx length %d\n", skb->len);
561 		}
562 		break;
563 
564 	/* stalls need manual reset. this is rare ... except that
565 	 * when going through USB 2.0 TTs, unplug appears this way.
566 	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
567 	 * storm, recovering as needed.
568 	 */
569 	case -EPIPE:
570 		dev->net->stats.rx_errors++;
571 		usbnet_defer_kevent (dev, EVENT_RX_HALT);
572 		// FALLTHROUGH
573 
574 	/* software-driven interface shutdown */
575 	case -ECONNRESET:		/* async unlink */
576 	case -ESHUTDOWN:		/* hardware gone */
577 		netif_dbg(dev, ifdown, dev->net,
578 			  "rx shutdown, code %d\n", urb_status);
579 		goto block;
580 
581 	/* we get controller i/o faults during khubd disconnect() delays.
582 	 * throttle down resubmits, to avoid log floods; just temporarily,
583 	 * so we still recover when the fault isn't a khubd delay.
584 	 */
585 	case -EPROTO:
586 	case -ETIME:
587 	case -EILSEQ:
588 		dev->net->stats.rx_errors++;
589 		if (!timer_pending (&dev->delay)) {
590 			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
591 			netif_dbg(dev, link, dev->net,
592 				  "rx throttle %d\n", urb_status);
593 		}
594 block:
595 		state = rx_cleanup;
596 		entry->urb = urb;
597 		urb = NULL;
598 		break;
599 
600 	/* data overrun ... flush fifo? */
601 	case -EOVERFLOW:
602 		dev->net->stats.rx_over_errors++;
603 		// FALLTHROUGH
604 
605 	default:
606 		state = rx_cleanup;
607 		dev->net->stats.rx_errors++;
608 		netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
609 		break;
610 	}
611 
612 	/* stop rx if packet error rate is high */
613 	if (++dev->pkt_cnt > 30) {
614 		dev->pkt_cnt = 0;
615 		dev->pkt_err = 0;
616 	} else {
617 		if (state == rx_cleanup)
618 			dev->pkt_err++;
619 		if (dev->pkt_err > 20)
620 			set_bit(EVENT_RX_KILL, &dev->flags);
621 	}
622 
623 	state = defer_bh(dev, skb, &dev->rxq, state);
624 
625 	if (urb) {
626 		if (netif_running (dev->net) &&
627 		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
628 		    state != unlink_start) {
629 			rx_submit (dev, urb, GFP_ATOMIC);
630 			usb_mark_last_busy(dev->udev);
631 			return;
632 		}
633 		usb_free_urb (urb);
634 	}
635 	netif_dbg(dev, rx_err, dev->net, "no read resubmitted\n");
636 }
637 
638 /*-------------------------------------------------------------------------*/
639 void usbnet_pause_rx(struct usbnet *dev)
640 {
641 	set_bit(EVENT_RX_PAUSED, &dev->flags);
642 
643 	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled\n");
644 }
645 EXPORT_SYMBOL_GPL(usbnet_pause_rx);
646 
647 void usbnet_resume_rx(struct usbnet *dev)
648 {
649 	struct sk_buff *skb;
650 	int num = 0;
651 
652 	clear_bit(EVENT_RX_PAUSED, &dev->flags);
653 
654 	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
655 		usbnet_skb_return(dev, skb);
656 		num++;
657 	}
658 
659 	tasklet_schedule(&dev->bh);
660 
661 	netif_dbg(dev, rx_status, dev->net,
662 		  "paused rx queue disabled, %d skbs requeued\n", num);
663 }
664 EXPORT_SYMBOL_GPL(usbnet_resume_rx);
665 
666 void usbnet_purge_paused_rxq(struct usbnet *dev)
667 {
668 	skb_queue_purge(&dev->rxq_pause);
669 }
670 EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
671 
672 /*-------------------------------------------------------------------------*/
673 
674 // unlink pending rx/tx; completion handlers do all other cleanup
675 
676 static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
677 {
678 	unsigned long		flags;
679 	struct sk_buff		*skb;
680 	int			count = 0;
681 
682 	spin_lock_irqsave (&q->lock, flags);
683 	while (!skb_queue_empty(q)) {
684 		struct skb_data		*entry;
685 		struct urb		*urb;
686 		int			retval;
687 
688 		skb_queue_walk(q, skb) {
689 			entry = (struct skb_data *) skb->cb;
690 			if (entry->state != unlink_start)
691 				goto found;
692 		}
693 		break;
694 found:
695 		entry->state = unlink_start;
696 		urb = entry->urb;
697 
698 		/*
699 		 * Get reference count of the URB to avoid it to be
700 		 * freed during usb_unlink_urb, which may trigger
701 		 * use-after-free problem inside usb_unlink_urb since
702 		 * usb_unlink_urb is always racing with .complete
703 		 * handler(include defer_bh).
704 		 */
705 		usb_get_urb(urb);
706 		spin_unlock_irqrestore(&q->lock, flags);
707 		// during some PM-driven resume scenarios,
708 		// these (async) unlinks complete immediately
709 		retval = usb_unlink_urb (urb);
710 		if (retval != -EINPROGRESS && retval != 0)
711 			netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
712 		else
713 			count++;
714 		usb_put_urb(urb);
715 		spin_lock_irqsave(&q->lock, flags);
716 	}
717 	spin_unlock_irqrestore (&q->lock, flags);
718 	return count;
719 }
720 
721 // Flush all pending rx urbs
722 // minidrivers may need to do this when the MTU changes
723 
724 void usbnet_unlink_rx_urbs(struct usbnet *dev)
725 {
726 	if (netif_running(dev->net)) {
727 		(void) unlink_urbs (dev, &dev->rxq);
728 		tasklet_schedule(&dev->bh);
729 	}
730 }
731 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
732 
733 /*-------------------------------------------------------------------------*/
734 
735 // precondition: never called in_interrupt
736 static void usbnet_terminate_urbs(struct usbnet *dev)
737 {
738 	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(unlink_wakeup);
739 	DECLARE_WAITQUEUE(wait, current);
740 	int temp;
741 
742 	/* ensure there are no more active urbs */
743 	add_wait_queue(&unlink_wakeup, &wait);
744 	set_current_state(TASK_UNINTERRUPTIBLE);
745 	dev->wait = &unlink_wakeup;
746 	temp = unlink_urbs(dev, &dev->txq) +
747 		unlink_urbs(dev, &dev->rxq);
748 
749 	/* maybe wait for deletions to finish. */
750 	while (!skb_queue_empty(&dev->rxq)
751 		&& !skb_queue_empty(&dev->txq)
752 		&& !skb_queue_empty(&dev->done)) {
753 			schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
754 			set_current_state(TASK_UNINTERRUPTIBLE);
755 			netif_dbg(dev, ifdown, dev->net,
756 				  "waited for %d urb completions\n", temp);
757 	}
758 	set_current_state(TASK_RUNNING);
759 	dev->wait = NULL;
760 	remove_wait_queue(&unlink_wakeup, &wait);
761 }
762 
763 int usbnet_stop (struct net_device *net)
764 {
765 	struct usbnet		*dev = netdev_priv(net);
766 	struct driver_info	*info = dev->driver_info;
767 	int			retval;
768 
769 	clear_bit(EVENT_DEV_OPEN, &dev->flags);
770 	netif_stop_queue (net);
771 
772 	netif_info(dev, ifdown, dev->net,
773 		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu\n",
774 		   net->stats.rx_packets, net->stats.tx_packets,
775 		   net->stats.rx_errors, net->stats.tx_errors);
776 
777 	/* allow minidriver to stop correctly (wireless devices to turn off
778 	 * radio etc) */
779 	if (info->stop) {
780 		retval = info->stop(dev);
781 		if (retval < 0)
782 			netif_info(dev, ifdown, dev->net,
783 				   "stop fail (%d) usbnet usb-%s-%s, %s\n",
784 				   retval,
785 				   dev->udev->bus->bus_name, dev->udev->devpath,
786 				   info->description);
787 	}
788 
789 	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
790 		usbnet_terminate_urbs(dev);
791 
792 	usbnet_status_stop(dev);
793 
794 	usbnet_purge_paused_rxq(dev);
795 
796 	/* deferred work (task, timer, softirq) must also stop.
797 	 * can't flush_scheduled_work() until we drop rtnl (later),
798 	 * else workers could deadlock; so make workers a NOP.
799 	 */
800 	dev->flags = 0;
801 	del_timer_sync (&dev->delay);
802 	tasklet_kill (&dev->bh);
803 	if (info->manage_power &&
804 	    !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))
805 		info->manage_power(dev, 0);
806 	else
807 		usb_autopm_put_interface(dev->intf);
808 
809 	return 0;
810 }
811 EXPORT_SYMBOL_GPL(usbnet_stop);
812 
813 /*-------------------------------------------------------------------------*/
814 
815 // posts reads, and enables write queuing
816 
817 // precondition: never called in_interrupt
818 
819 int usbnet_open (struct net_device *net)
820 {
821 	struct usbnet		*dev = netdev_priv(net);
822 	int			retval;
823 	struct driver_info	*info = dev->driver_info;
824 
825 	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
826 		netif_info(dev, ifup, dev->net,
827 			   "resumption fail (%d) usbnet usb-%s-%s, %s\n",
828 			   retval,
829 			   dev->udev->bus->bus_name,
830 			   dev->udev->devpath,
831 			   info->description);
832 		goto done_nopm;
833 	}
834 
835 	// put into "known safe" state
836 	if (info->reset && (retval = info->reset (dev)) < 0) {
837 		netif_info(dev, ifup, dev->net,
838 			   "open reset fail (%d) usbnet usb-%s-%s, %s\n",
839 			   retval,
840 			   dev->udev->bus->bus_name,
841 			   dev->udev->devpath,
842 			   info->description);
843 		goto done;
844 	}
845 
846 	// insist peer be connected
847 	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
848 		netif_dbg(dev, ifup, dev->net, "can't open; %d\n", retval);
849 		goto done;
850 	}
851 
852 	/* start any status interrupt transfer */
853 	if (dev->interrupt) {
854 		retval = usbnet_status_start(dev, GFP_KERNEL);
855 		if (retval < 0) {
856 			netif_err(dev, ifup, dev->net,
857 				  "intr submit %d\n", retval);
858 			goto done;
859 		}
860 	}
861 
862 	set_bit(EVENT_DEV_OPEN, &dev->flags);
863 	netif_start_queue (net);
864 	netif_info(dev, ifup, dev->net,
865 		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing\n",
866 		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
867 		   dev->net->mtu,
868 		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
869 		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
870 		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
871 		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
872 		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
873 		   "simple");
874 
875 	/* reset rx error state */
876 	dev->pkt_cnt = 0;
877 	dev->pkt_err = 0;
878 	clear_bit(EVENT_RX_KILL, &dev->flags);
879 
880 	// delay posting reads until we're fully open
881 	tasklet_schedule (&dev->bh);
882 	if (info->manage_power) {
883 		retval = info->manage_power(dev, 1);
884 		if (retval < 0) {
885 			retval = 0;
886 			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
887 		} else {
888 			usb_autopm_put_interface(dev->intf);
889 		}
890 	}
891 	return retval;
892 done:
893 	usb_autopm_put_interface(dev->intf);
894 done_nopm:
895 	return retval;
896 }
897 EXPORT_SYMBOL_GPL(usbnet_open);
898 
899 /*-------------------------------------------------------------------------*/
900 
901 /* ethtool methods; minidrivers may need to add some more, but
902  * they'll probably want to use this base set.
903  */
904 
905 int usbnet_get_settings (struct net_device *net, struct ethtool_cmd *cmd)
906 {
907 	struct usbnet *dev = netdev_priv(net);
908 
909 	if (!dev->mii.mdio_read)
910 		return -EOPNOTSUPP;
911 
912 	return mii_ethtool_gset(&dev->mii, cmd);
913 }
914 EXPORT_SYMBOL_GPL(usbnet_get_settings);
915 
916 int usbnet_set_settings (struct net_device *net, struct ethtool_cmd *cmd)
917 {
918 	struct usbnet *dev = netdev_priv(net);
919 	int retval;
920 
921 	if (!dev->mii.mdio_write)
922 		return -EOPNOTSUPP;
923 
924 	retval = mii_ethtool_sset(&dev->mii, cmd);
925 
926 	/* link speed/duplex might have changed */
927 	if (dev->driver_info->link_reset)
928 		dev->driver_info->link_reset(dev);
929 
930 	return retval;
931 
932 }
933 EXPORT_SYMBOL_GPL(usbnet_set_settings);
934 
935 u32 usbnet_get_link (struct net_device *net)
936 {
937 	struct usbnet *dev = netdev_priv(net);
938 
939 	/* If a check_connect is defined, return its result */
940 	if (dev->driver_info->check_connect)
941 		return dev->driver_info->check_connect (dev) == 0;
942 
943 	/* if the device has mii operations, use those */
944 	if (dev->mii.mdio_read)
945 		return mii_link_ok(&dev->mii);
946 
947 	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
948 	return ethtool_op_get_link(net);
949 }
950 EXPORT_SYMBOL_GPL(usbnet_get_link);
951 
952 int usbnet_nway_reset(struct net_device *net)
953 {
954 	struct usbnet *dev = netdev_priv(net);
955 
956 	if (!dev->mii.mdio_write)
957 		return -EOPNOTSUPP;
958 
959 	return mii_nway_restart(&dev->mii);
960 }
961 EXPORT_SYMBOL_GPL(usbnet_nway_reset);
962 
963 void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
964 {
965 	struct usbnet *dev = netdev_priv(net);
966 
967 	strlcpy (info->driver, dev->driver_name, sizeof info->driver);
968 	strlcpy (info->version, DRIVER_VERSION, sizeof info->version);
969 	strlcpy (info->fw_version, dev->driver_info->description,
970 		sizeof info->fw_version);
971 	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
972 }
973 EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
974 
975 u32 usbnet_get_msglevel (struct net_device *net)
976 {
977 	struct usbnet *dev = netdev_priv(net);
978 
979 	return dev->msg_enable;
980 }
981 EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
982 
983 void usbnet_set_msglevel (struct net_device *net, u32 level)
984 {
985 	struct usbnet *dev = netdev_priv(net);
986 
987 	dev->msg_enable = level;
988 }
989 EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
990 
991 /* drivers may override default ethtool_ops in their bind() routine */
992 static const struct ethtool_ops usbnet_ethtool_ops = {
993 	.get_settings		= usbnet_get_settings,
994 	.set_settings		= usbnet_set_settings,
995 	.get_link		= usbnet_get_link,
996 	.nway_reset		= usbnet_nway_reset,
997 	.get_drvinfo		= usbnet_get_drvinfo,
998 	.get_msglevel		= usbnet_get_msglevel,
999 	.set_msglevel		= usbnet_set_msglevel,
1000 	.get_ts_info		= ethtool_op_get_ts_info,
1001 };
1002 
1003 /*-------------------------------------------------------------------------*/
1004 
1005 static void __handle_link_change(struct usbnet *dev)
1006 {
1007 	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
1008 		return;
1009 
1010 	if (!netif_carrier_ok(dev->net)) {
1011 		/* kill URBs for reading packets to save bus bandwidth */
1012 		unlink_urbs(dev, &dev->rxq);
1013 
1014 		/*
1015 		 * tx_timeout will unlink URBs for sending packets and
1016 		 * tx queue is stopped by netcore after link becomes off
1017 		 */
1018 	} else {
1019 		/* submitting URBs for reading packets */
1020 		tasklet_schedule(&dev->bh);
1021 	}
1022 
1023 	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
1024 }
1025 
1026 /* work that cannot be done in interrupt context uses keventd.
1027  *
1028  * NOTE:  with 2.5 we could do more of this using completion callbacks,
1029  * especially now that control transfers can be queued.
1030  */
1031 static void
1032 kevent (struct work_struct *work)
1033 {
1034 	struct usbnet		*dev =
1035 		container_of(work, struct usbnet, kevent);
1036 	int			status;
1037 
1038 	/* usb_clear_halt() needs a thread context */
1039 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
1040 		unlink_urbs (dev, &dev->txq);
1041 		status = usb_autopm_get_interface(dev->intf);
1042 		if (status < 0)
1043 			goto fail_pipe;
1044 		status = usb_clear_halt (dev->udev, dev->out);
1045 		usb_autopm_put_interface(dev->intf);
1046 		if (status < 0 &&
1047 		    status != -EPIPE &&
1048 		    status != -ESHUTDOWN) {
1049 			if (netif_msg_tx_err (dev))
1050 fail_pipe:
1051 				netdev_err(dev->net, "can't clear tx halt, status %d\n",
1052 					   status);
1053 		} else {
1054 			clear_bit (EVENT_TX_HALT, &dev->flags);
1055 			if (status != -ESHUTDOWN)
1056 				netif_wake_queue (dev->net);
1057 		}
1058 	}
1059 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
1060 		unlink_urbs (dev, &dev->rxq);
1061 		status = usb_autopm_get_interface(dev->intf);
1062 		if (status < 0)
1063 			goto fail_halt;
1064 		status = usb_clear_halt (dev->udev, dev->in);
1065 		usb_autopm_put_interface(dev->intf);
1066 		if (status < 0 &&
1067 		    status != -EPIPE &&
1068 		    status != -ESHUTDOWN) {
1069 			if (netif_msg_rx_err (dev))
1070 fail_halt:
1071 				netdev_err(dev->net, "can't clear rx halt, status %d\n",
1072 					   status);
1073 		} else {
1074 			clear_bit (EVENT_RX_HALT, &dev->flags);
1075 			tasklet_schedule (&dev->bh);
1076 		}
1077 	}
1078 
1079 	/* tasklet could resubmit itself forever if memory is tight */
1080 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
1081 		struct urb	*urb = NULL;
1082 		int resched = 1;
1083 
1084 		if (netif_running (dev->net))
1085 			urb = usb_alloc_urb (0, GFP_KERNEL);
1086 		else
1087 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1088 		if (urb != NULL) {
1089 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1090 			status = usb_autopm_get_interface(dev->intf);
1091 			if (status < 0) {
1092 				usb_free_urb(urb);
1093 				goto fail_lowmem;
1094 			}
1095 			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
1096 				resched = 0;
1097 			usb_autopm_put_interface(dev->intf);
1098 fail_lowmem:
1099 			if (resched)
1100 				tasklet_schedule (&dev->bh);
1101 		}
1102 	}
1103 
1104 	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
1105 		struct driver_info	*info = dev->driver_info;
1106 		int			retval = 0;
1107 
1108 		clear_bit (EVENT_LINK_RESET, &dev->flags);
1109 		status = usb_autopm_get_interface(dev->intf);
1110 		if (status < 0)
1111 			goto skip_reset;
1112 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
1113 			usb_autopm_put_interface(dev->intf);
1114 skip_reset:
1115 			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s\n",
1116 				    retval,
1117 				    dev->udev->bus->bus_name,
1118 				    dev->udev->devpath,
1119 				    info->description);
1120 		} else {
1121 			usb_autopm_put_interface(dev->intf);
1122 		}
1123 
1124 		/* handle link change from link resetting */
1125 		__handle_link_change(dev);
1126 	}
1127 
1128 	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
1129 		__handle_link_change(dev);
1130 
1131 	if (dev->flags)
1132 		netdev_dbg(dev->net, "kevent done, flags = 0x%lx\n", dev->flags);
1133 }
1134 
1135 /*-------------------------------------------------------------------------*/
1136 
1137 static void tx_complete (struct urb *urb)
1138 {
1139 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
1140 	struct skb_data		*entry = (struct skb_data *) skb->cb;
1141 	struct usbnet		*dev = entry->dev;
1142 
1143 	if (urb->status == 0) {
1144 		if (!(dev->driver_info->flags & FLAG_MULTI_PACKET))
1145 			dev->net->stats.tx_packets++;
1146 		dev->net->stats.tx_bytes += entry->length;
1147 	} else {
1148 		dev->net->stats.tx_errors++;
1149 
1150 		switch (urb->status) {
1151 		case -EPIPE:
1152 			usbnet_defer_kevent (dev, EVENT_TX_HALT);
1153 			break;
1154 
1155 		/* software-driven interface shutdown */
1156 		case -ECONNRESET:		// async unlink
1157 		case -ESHUTDOWN:		// hardware gone
1158 			break;
1159 
1160 		// like rx, tx gets controller i/o faults during khubd delays
1161 		// and so it uses the same throttling mechanism.
1162 		case -EPROTO:
1163 		case -ETIME:
1164 		case -EILSEQ:
1165 			usb_mark_last_busy(dev->udev);
1166 			if (!timer_pending (&dev->delay)) {
1167 				mod_timer (&dev->delay,
1168 					jiffies + THROTTLE_JIFFIES);
1169 				netif_dbg(dev, link, dev->net,
1170 					  "tx throttle %d\n", urb->status);
1171 			}
1172 			netif_stop_queue (dev->net);
1173 			break;
1174 		default:
1175 			netif_dbg(dev, tx_err, dev->net,
1176 				  "tx err %d\n", entry->urb->status);
1177 			break;
1178 		}
1179 	}
1180 
1181 	usb_autopm_put_interface_async(dev->intf);
1182 	(void) defer_bh(dev, skb, &dev->txq, tx_done);
1183 }
1184 
1185 /*-------------------------------------------------------------------------*/
1186 
1187 void usbnet_tx_timeout (struct net_device *net)
1188 {
1189 	struct usbnet		*dev = netdev_priv(net);
1190 
1191 	unlink_urbs (dev, &dev->txq);
1192 	tasklet_schedule (&dev->bh);
1193 
1194 	// FIXME: device recovery -- reset?
1195 }
1196 EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
1197 
1198 /*-------------------------------------------------------------------------*/
1199 
1200 netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
1201 				     struct net_device *net)
1202 {
1203 	struct usbnet		*dev = netdev_priv(net);
1204 	int			length;
1205 	struct urb		*urb = NULL;
1206 	struct skb_data		*entry;
1207 	struct driver_info	*info = dev->driver_info;
1208 	unsigned long		flags;
1209 	int retval;
1210 
1211 	if (skb)
1212 		skb_tx_timestamp(skb);
1213 
1214 	// some devices want funky USB-level framing, for
1215 	// win32 driver (usually) and/or hardware quirks
1216 	if (info->tx_fixup) {
1217 		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
1218 		if (!skb) {
1219 			/* packet collected; minidriver waiting for more */
1220 			if (info->flags & FLAG_MULTI_PACKET)
1221 				goto not_drop;
1222 			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
1223 			goto drop;
1224 		}
1225 	}
1226 	length = skb->len;
1227 
1228 	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
1229 		netif_dbg(dev, tx_err, dev->net, "no urb\n");
1230 		goto drop;
1231 	}
1232 
1233 	entry = (struct skb_data *) skb->cb;
1234 	entry->urb = urb;
1235 	entry->dev = dev;
1236 	entry->length = length;
1237 
1238 	usb_fill_bulk_urb (urb, dev->udev, dev->out,
1239 			skb->data, skb->len, tx_complete, skb);
1240 
1241 	/* don't assume the hardware handles USB_ZERO_PACKET
1242 	 * NOTE:  strictly conforming cdc-ether devices should expect
1243 	 * the ZLP here, but ignore the one-byte packet.
1244 	 * NOTE2: CDC NCM specification is different from CDC ECM when
1245 	 * handling ZLP/short packets, so cdc_ncm driver will make short
1246 	 * packet itself if needed.
1247 	 */
1248 	if (length % dev->maxpacket == 0) {
1249 		if (!(info->flags & FLAG_SEND_ZLP)) {
1250 			if (!(info->flags & FLAG_MULTI_PACKET)) {
1251 				urb->transfer_buffer_length++;
1252 				if (skb_tailroom(skb)) {
1253 					skb->data[skb->len] = 0;
1254 					__skb_put(skb, 1);
1255 				}
1256 			}
1257 		} else
1258 			urb->transfer_flags |= URB_ZERO_PACKET;
1259 	}
1260 
1261 	spin_lock_irqsave(&dev->txq.lock, flags);
1262 	retval = usb_autopm_get_interface_async(dev->intf);
1263 	if (retval < 0) {
1264 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1265 		goto drop;
1266 	}
1267 
1268 #ifdef CONFIG_PM
1269 	/* if this triggers the device is still a sleep */
1270 	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
1271 		/* transmission will be done in resume */
1272 		usb_anchor_urb(urb, &dev->deferred);
1273 		/* no use to process more packets */
1274 		netif_stop_queue(net);
1275 		usb_put_urb(urb);
1276 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1277 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
1278 		goto deferred;
1279 	}
1280 #endif
1281 
1282 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
1283 	case -EPIPE:
1284 		netif_stop_queue (net);
1285 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
1286 		usb_autopm_put_interface_async(dev->intf);
1287 		break;
1288 	default:
1289 		usb_autopm_put_interface_async(dev->intf);
1290 		netif_dbg(dev, tx_err, dev->net,
1291 			  "tx: submit urb err %d\n", retval);
1292 		break;
1293 	case 0:
1294 		net->trans_start = jiffies;
1295 		__usbnet_queue_skb(&dev->txq, skb, tx_start);
1296 		if (dev->txq.qlen >= TX_QLEN (dev))
1297 			netif_stop_queue (net);
1298 	}
1299 	spin_unlock_irqrestore (&dev->txq.lock, flags);
1300 
1301 	if (retval) {
1302 		netif_dbg(dev, tx_err, dev->net, "drop, code %d\n", retval);
1303 drop:
1304 		dev->net->stats.tx_dropped++;
1305 not_drop:
1306 		if (skb)
1307 			dev_kfree_skb_any (skb);
1308 		usb_free_urb (urb);
1309 	} else
1310 		netif_dbg(dev, tx_queued, dev->net,
1311 			  "> tx, len %d, type 0x%x\n", length, skb->protocol);
1312 #ifdef CONFIG_PM
1313 deferred:
1314 #endif
1315 	return NETDEV_TX_OK;
1316 }
1317 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
1318 
1319 static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
1320 {
1321 	struct urb	*urb;
1322 	int		i;
1323 	int		ret = 0;
1324 
1325 	/* don't refill the queue all at once */
1326 	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
1327 		urb = usb_alloc_urb(0, flags);
1328 		if (urb != NULL) {
1329 			ret = rx_submit(dev, urb, flags);
1330 			if (ret)
1331 				goto err;
1332 		} else {
1333 			ret = -ENOMEM;
1334 			goto err;
1335 		}
1336 	}
1337 err:
1338 	return ret;
1339 }
1340 
1341 /*-------------------------------------------------------------------------*/
1342 
1343 // tasklet (work deferred from completions, in_irq) or timer
1344 
1345 static void usbnet_bh (unsigned long param)
1346 {
1347 	struct usbnet		*dev = (struct usbnet *) param;
1348 	struct sk_buff		*skb;
1349 	struct skb_data		*entry;
1350 
1351 	while ((skb = skb_dequeue (&dev->done))) {
1352 		entry = (struct skb_data *) skb->cb;
1353 		switch (entry->state) {
1354 		case rx_done:
1355 			entry->state = rx_cleanup;
1356 			rx_process (dev, skb);
1357 			continue;
1358 		case tx_done:
1359 		case rx_cleanup:
1360 			usb_free_urb (entry->urb);
1361 			dev_kfree_skb (skb);
1362 			continue;
1363 		default:
1364 			netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
1365 		}
1366 	}
1367 
1368 	/* restart RX again after disabling due to high error rate */
1369 	clear_bit(EVENT_RX_KILL, &dev->flags);
1370 
1371 	// waiting for all pending urbs to complete?
1372 	if (dev->wait) {
1373 		if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
1374 			wake_up (dev->wait);
1375 		}
1376 
1377 	// or are we maybe short a few urbs?
1378 	} else if (netif_running (dev->net) &&
1379 		   netif_device_present (dev->net) &&
1380 		   netif_carrier_ok(dev->net) &&
1381 		   !timer_pending (&dev->delay) &&
1382 		   !test_bit (EVENT_RX_HALT, &dev->flags)) {
1383 		int	temp = dev->rxq.qlen;
1384 
1385 		if (temp < RX_QLEN(dev)) {
1386 			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
1387 				return;
1388 			if (temp != dev->rxq.qlen)
1389 				netif_dbg(dev, link, dev->net,
1390 					  "rxqlen %d --> %d\n",
1391 					  temp, dev->rxq.qlen);
1392 			if (dev->rxq.qlen < RX_QLEN(dev))
1393 				tasklet_schedule (&dev->bh);
1394 		}
1395 		if (dev->txq.qlen < TX_QLEN (dev))
1396 			netif_wake_queue (dev->net);
1397 	}
1398 }
1399 
1400 
1401 /*-------------------------------------------------------------------------
1402  *
1403  * USB Device Driver support
1404  *
1405  *-------------------------------------------------------------------------*/
1406 
1407 // precondition: never called in_interrupt
1408 
1409 void usbnet_disconnect (struct usb_interface *intf)
1410 {
1411 	struct usbnet		*dev;
1412 	struct usb_device	*xdev;
1413 	struct net_device	*net;
1414 
1415 	dev = usb_get_intfdata(intf);
1416 	usb_set_intfdata(intf, NULL);
1417 	if (!dev)
1418 		return;
1419 
1420 	xdev = interface_to_usbdev (intf);
1421 
1422 	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s\n",
1423 		   intf->dev.driver->name,
1424 		   xdev->bus->bus_name, xdev->devpath,
1425 		   dev->driver_info->description);
1426 
1427 	net = dev->net;
1428 	unregister_netdev (net);
1429 
1430 	cancel_work_sync(&dev->kevent);
1431 
1432 	usb_scuttle_anchored_urbs(&dev->deferred);
1433 
1434 	if (dev->driver_info->unbind)
1435 		dev->driver_info->unbind (dev, intf);
1436 
1437 	usb_kill_urb(dev->interrupt);
1438 	usb_free_urb(dev->interrupt);
1439 
1440 	free_netdev(net);
1441 }
1442 EXPORT_SYMBOL_GPL(usbnet_disconnect);
1443 
1444 static const struct net_device_ops usbnet_netdev_ops = {
1445 	.ndo_open		= usbnet_open,
1446 	.ndo_stop		= usbnet_stop,
1447 	.ndo_start_xmit		= usbnet_start_xmit,
1448 	.ndo_tx_timeout		= usbnet_tx_timeout,
1449 	.ndo_change_mtu		= usbnet_change_mtu,
1450 	.ndo_set_mac_address 	= eth_mac_addr,
1451 	.ndo_validate_addr	= eth_validate_addr,
1452 };
1453 
1454 /*-------------------------------------------------------------------------*/
1455 
1456 // precondition: never called in_interrupt
1457 
1458 static struct device_type wlan_type = {
1459 	.name	= "wlan",
1460 };
1461 
1462 static struct device_type wwan_type = {
1463 	.name	= "wwan",
1464 };
1465 
1466 int
1467 usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
1468 {
1469 	struct usbnet			*dev;
1470 	struct net_device		*net;
1471 	struct usb_host_interface	*interface;
1472 	struct driver_info		*info;
1473 	struct usb_device		*xdev;
1474 	int				status;
1475 	const char			*name;
1476 	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
1477 
1478 	/* usbnet already took usb runtime pm, so have to enable the feature
1479 	 * for usb interface, otherwise usb_autopm_get_interface may return
1480 	 * failure if RUNTIME_PM is enabled.
1481 	 */
1482 	if (!driver->supports_autosuspend) {
1483 		driver->supports_autosuspend = 1;
1484 		pm_runtime_enable(&udev->dev);
1485 	}
1486 
1487 	name = udev->dev.driver->name;
1488 	info = (struct driver_info *) prod->driver_info;
1489 	if (!info) {
1490 		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
1491 		return -ENODEV;
1492 	}
1493 	xdev = interface_to_usbdev (udev);
1494 	interface = udev->cur_altsetting;
1495 
1496 	status = -ENOMEM;
1497 
1498 	// set up our own records
1499 	net = alloc_etherdev(sizeof(*dev));
1500 	if (!net)
1501 		goto out;
1502 
1503 	/* netdev_printk() needs this so do it as early as possible */
1504 	SET_NETDEV_DEV(net, &udev->dev);
1505 
1506 	dev = netdev_priv(net);
1507 	dev->udev = xdev;
1508 	dev->intf = udev;
1509 	dev->driver_info = info;
1510 	dev->driver_name = name;
1511 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
1512 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
1513 	skb_queue_head_init (&dev->rxq);
1514 	skb_queue_head_init (&dev->txq);
1515 	skb_queue_head_init (&dev->done);
1516 	skb_queue_head_init(&dev->rxq_pause);
1517 	dev->bh.func = usbnet_bh;
1518 	dev->bh.data = (unsigned long) dev;
1519 	INIT_WORK (&dev->kevent, kevent);
1520 	init_usb_anchor(&dev->deferred);
1521 	dev->delay.function = usbnet_bh;
1522 	dev->delay.data = (unsigned long) dev;
1523 	init_timer (&dev->delay);
1524 	mutex_init (&dev->phy_mutex);
1525 	mutex_init(&dev->interrupt_mutex);
1526 	dev->interrupt_count = 0;
1527 
1528 	dev->net = net;
1529 	strcpy (net->name, "usb%d");
1530 	memcpy (net->dev_addr, node_id, sizeof node_id);
1531 
1532 	/* rx and tx sides can use different message sizes;
1533 	 * bind() should set rx_urb_size in that case.
1534 	 */
1535 	dev->hard_mtu = net->mtu + net->hard_header_len;
1536 #if 0
1537 // dma_supported() is deeply broken on almost all architectures
1538 	// possible with some EHCI controllers
1539 	if (dma_supported (&udev->dev, DMA_BIT_MASK(64)))
1540 		net->features |= NETIF_F_HIGHDMA;
1541 #endif
1542 
1543 	net->netdev_ops = &usbnet_netdev_ops;
1544 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
1545 	net->ethtool_ops = &usbnet_ethtool_ops;
1546 
1547 	// allow device-specific bind/init procedures
1548 	// NOTE net->name still not usable ...
1549 	if (info->bind) {
1550 		status = info->bind (dev, udev);
1551 		if (status < 0)
1552 			goto out1;
1553 
1554 		// heuristic:  "usb%d" for links we know are two-host,
1555 		// else "eth%d" when there's reasonable doubt.  userspace
1556 		// can rename the link if it knows better.
1557 		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
1558 		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
1559 		     (net->dev_addr [0] & 0x02) == 0))
1560 			strcpy (net->name, "eth%d");
1561 		/* WLAN devices should always be named "wlan%d" */
1562 		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1563 			strcpy(net->name, "wlan%d");
1564 		/* WWAN devices should always be named "wwan%d" */
1565 		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1566 			strcpy(net->name, "wwan%d");
1567 
1568 		/* devices that cannot do ARP */
1569 		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
1570 			net->flags |= IFF_NOARP;
1571 
1572 		/* maybe the remote can't receive an Ethernet MTU */
1573 		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
1574 			net->mtu = dev->hard_mtu - net->hard_header_len;
1575 	} else if (!info->in || !info->out)
1576 		status = usbnet_get_endpoints (dev, udev);
1577 	else {
1578 		dev->in = usb_rcvbulkpipe (xdev, info->in);
1579 		dev->out = usb_sndbulkpipe (xdev, info->out);
1580 		if (!(info->flags & FLAG_NO_SETINT))
1581 			status = usb_set_interface (xdev,
1582 				interface->desc.bInterfaceNumber,
1583 				interface->desc.bAlternateSetting);
1584 		else
1585 			status = 0;
1586 
1587 	}
1588 	if (status >= 0 && dev->status)
1589 		status = init_status (dev, udev);
1590 	if (status < 0)
1591 		goto out3;
1592 
1593 	if (!dev->rx_urb_size)
1594 		dev->rx_urb_size = dev->hard_mtu;
1595 	dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
1596 
1597 	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1598 		SET_NETDEV_DEVTYPE(net, &wlan_type);
1599 	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1600 		SET_NETDEV_DEVTYPE(net, &wwan_type);
1601 
1602 	status = register_netdev (net);
1603 	if (status)
1604 		goto out4;
1605 	netif_info(dev, probe, dev->net,
1606 		   "register '%s' at usb-%s-%s, %s, %pM\n",
1607 		   udev->dev.driver->name,
1608 		   xdev->bus->bus_name, xdev->devpath,
1609 		   dev->driver_info->description,
1610 		   net->dev_addr);
1611 
1612 	// ok, it's ready to go.
1613 	usb_set_intfdata (udev, dev);
1614 
1615 	netif_device_attach (net);
1616 
1617 	if (dev->driver_info->flags & FLAG_LINK_INTR)
1618 		usbnet_link_change(dev, 0, 0);
1619 
1620 	return 0;
1621 
1622 out4:
1623 	usb_free_urb(dev->interrupt);
1624 out3:
1625 	if (info->unbind)
1626 		info->unbind (dev, udev);
1627 out1:
1628 	free_netdev(net);
1629 out:
1630 	return status;
1631 }
1632 EXPORT_SYMBOL_GPL(usbnet_probe);
1633 
1634 /*-------------------------------------------------------------------------*/
1635 
1636 /*
1637  * suspend the whole driver as soon as the first interface is suspended
1638  * resume only when the last interface is resumed
1639  */
1640 
1641 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
1642 {
1643 	struct usbnet		*dev = usb_get_intfdata(intf);
1644 
1645 	if (!dev->suspend_count++) {
1646 		spin_lock_irq(&dev->txq.lock);
1647 		/* don't autosuspend while transmitting */
1648 		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
1649 			dev->suspend_count--;
1650 			spin_unlock_irq(&dev->txq.lock);
1651 			return -EBUSY;
1652 		} else {
1653 			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
1654 			spin_unlock_irq(&dev->txq.lock);
1655 		}
1656 		/*
1657 		 * accelerate emptying of the rx and queues, to avoid
1658 		 * having everything error out.
1659 		 */
1660 		netif_device_detach (dev->net);
1661 		usbnet_terminate_urbs(dev);
1662 		__usbnet_status_stop_force(dev);
1663 
1664 		/*
1665 		 * reattach so runtime management can use and
1666 		 * wake the device
1667 		 */
1668 		netif_device_attach (dev->net);
1669 	}
1670 	return 0;
1671 }
1672 EXPORT_SYMBOL_GPL(usbnet_suspend);
1673 
1674 int usbnet_resume (struct usb_interface *intf)
1675 {
1676 	struct usbnet		*dev = usb_get_intfdata(intf);
1677 	struct sk_buff          *skb;
1678 	struct urb              *res;
1679 	int                     retval;
1680 
1681 	if (!--dev->suspend_count) {
1682 		/* resume interrupt URB if it was previously submitted */
1683 		__usbnet_status_start_force(dev, GFP_NOIO);
1684 
1685 		spin_lock_irq(&dev->txq.lock);
1686 		while ((res = usb_get_from_anchor(&dev->deferred))) {
1687 
1688 			skb = (struct sk_buff *)res->context;
1689 			retval = usb_submit_urb(res, GFP_ATOMIC);
1690 			if (retval < 0) {
1691 				dev_kfree_skb_any(skb);
1692 				usb_free_urb(res);
1693 				usb_autopm_put_interface_async(dev->intf);
1694 			} else {
1695 				dev->net->trans_start = jiffies;
1696 				__skb_queue_tail(&dev->txq, skb);
1697 			}
1698 		}
1699 
1700 		smp_mb();
1701 		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
1702 		spin_unlock_irq(&dev->txq.lock);
1703 
1704 		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
1705 			/* handle remote wakeup ASAP */
1706 			if (!dev->wait &&
1707 				netif_device_present(dev->net) &&
1708 				!timer_pending(&dev->delay) &&
1709 				!test_bit(EVENT_RX_HALT, &dev->flags))
1710 					rx_alloc_submit(dev, GFP_NOIO);
1711 
1712 			if (!(dev->txq.qlen >= TX_QLEN(dev)))
1713 				netif_tx_wake_all_queues(dev->net);
1714 			tasklet_schedule (&dev->bh);
1715 		}
1716 	}
1717 
1718 	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
1719 		usb_autopm_get_interface_no_resume(intf);
1720 
1721 	return 0;
1722 }
1723 EXPORT_SYMBOL_GPL(usbnet_resume);
1724 
1725 /*
1726  * Either a subdriver implements manage_power, then it is assumed to always
1727  * be ready to be suspended or it reports the readiness to be suspended
1728  * explicitly
1729  */
1730 void usbnet_device_suggests_idle(struct usbnet *dev)
1731 {
1732 	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
1733 		dev->intf->needs_remote_wakeup = 1;
1734 		usb_autopm_put_interface_async(dev->intf);
1735 	}
1736 }
1737 EXPORT_SYMBOL(usbnet_device_suggests_idle);
1738 
1739 /*
1740  * For devices that can do without special commands
1741  */
1742 int usbnet_manage_power(struct usbnet *dev, int on)
1743 {
1744 	dev->intf->needs_remote_wakeup = on;
1745 	return 0;
1746 }
1747 EXPORT_SYMBOL(usbnet_manage_power);
1748 
1749 void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
1750 {
1751 	/* update link after link is reseted */
1752 	if (link && !need_reset)
1753 		netif_carrier_on(dev->net);
1754 	else
1755 		netif_carrier_off(dev->net);
1756 
1757 	if (need_reset && link)
1758 		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
1759 	else
1760 		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
1761 }
1762 EXPORT_SYMBOL(usbnet_link_change);
1763 
1764 /*-------------------------------------------------------------------------*/
1765 static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1766 			     u16 value, u16 index, void *data, u16 size)
1767 {
1768 	void *buf = NULL;
1769 	int err = -ENOMEM;
1770 
1771 	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
1772 		   " value=0x%04x index=0x%04x size=%d\n",
1773 		   cmd, reqtype, value, index, size);
1774 
1775 	if (data) {
1776 		buf = kmalloc(size, GFP_KERNEL);
1777 		if (!buf)
1778 			goto out;
1779 	}
1780 
1781 	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
1782 			      cmd, reqtype, value, index, buf, size,
1783 			      USB_CTRL_GET_TIMEOUT);
1784 	if (err > 0 && err <= size)
1785 		memcpy(data, buf, err);
1786 	kfree(buf);
1787 out:
1788 	return err;
1789 }
1790 
1791 static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1792 			      u16 value, u16 index, const void *data,
1793 			      u16 size)
1794 {
1795 	void *buf = NULL;
1796 	int err = -ENOMEM;
1797 
1798 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
1799 		   " value=0x%04x index=0x%04x size=%d\n",
1800 		   cmd, reqtype, value, index, size);
1801 
1802 	if (data) {
1803 		buf = kmemdup(data, size, GFP_KERNEL);
1804 		if (!buf)
1805 			goto out;
1806 	}
1807 
1808 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
1809 			      cmd, reqtype, value, index, buf, size,
1810 			      USB_CTRL_SET_TIMEOUT);
1811 	kfree(buf);
1812 
1813 out:
1814 	return err;
1815 }
1816 
1817 /*
1818  * The function can't be called inside suspend/resume callback,
1819  * otherwise deadlock will be caused.
1820  */
1821 int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1822 		    u16 value, u16 index, void *data, u16 size)
1823 {
1824 	int ret;
1825 
1826 	if (usb_autopm_get_interface(dev->intf) < 0)
1827 		return -ENODEV;
1828 	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
1829 				data, size);
1830 	usb_autopm_put_interface(dev->intf);
1831 	return ret;
1832 }
1833 EXPORT_SYMBOL_GPL(usbnet_read_cmd);
1834 
1835 /*
1836  * The function can't be called inside suspend/resume callback,
1837  * otherwise deadlock will be caused.
1838  */
1839 int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1840 		     u16 value, u16 index, const void *data, u16 size)
1841 {
1842 	int ret;
1843 
1844 	if (usb_autopm_get_interface(dev->intf) < 0)
1845 		return -ENODEV;
1846 	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
1847 				 data, size);
1848 	usb_autopm_put_interface(dev->intf);
1849 	return ret;
1850 }
1851 EXPORT_SYMBOL_GPL(usbnet_write_cmd);
1852 
1853 /*
1854  * The function can be called inside suspend/resume callback safely
1855  * and should only be called by suspend/resume callback generally.
1856  */
1857 int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
1858 			  u16 value, u16 index, void *data, u16 size)
1859 {
1860 	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
1861 				 data, size);
1862 }
1863 EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
1864 
1865 /*
1866  * The function can be called inside suspend/resume callback safely
1867  * and should only be called by suspend/resume callback generally.
1868  */
1869 int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
1870 			  u16 value, u16 index, const void *data,
1871 			  u16 size)
1872 {
1873 	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
1874 				  data, size);
1875 }
1876 EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
1877 
1878 static void usbnet_async_cmd_cb(struct urb *urb)
1879 {
1880 	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
1881 	int status = urb->status;
1882 
1883 	if (status < 0)
1884 		dev_dbg(&urb->dev->dev, "%s failed with %d",
1885 			__func__, status);
1886 
1887 	kfree(req);
1888 	usb_free_urb(urb);
1889 }
1890 
1891 /*
1892  * The caller must make sure that device can't be put into suspend
1893  * state until the control URB completes.
1894  */
1895 int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
1896 			   u16 value, u16 index, const void *data, u16 size)
1897 {
1898 	struct usb_ctrlrequest *req = NULL;
1899 	struct urb *urb;
1900 	int err = -ENOMEM;
1901 	void *buf = NULL;
1902 
1903 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
1904 		   " value=0x%04x index=0x%04x size=%d\n",
1905 		   cmd, reqtype, value, index, size);
1906 
1907 	urb = usb_alloc_urb(0, GFP_ATOMIC);
1908 	if (!urb) {
1909 		netdev_err(dev->net, "Error allocating URB in"
1910 			   " %s!\n", __func__);
1911 		goto fail;
1912 	}
1913 
1914 	if (data) {
1915 		buf = kmemdup(data, size, GFP_ATOMIC);
1916 		if (!buf) {
1917 			netdev_err(dev->net, "Error allocating buffer"
1918 				   " in %s!\n", __func__);
1919 			goto fail_free;
1920 		}
1921 	}
1922 
1923 	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
1924 	if (!req)
1925 		goto fail_free_buf;
1926 
1927 	req->bRequestType = reqtype;
1928 	req->bRequest = cmd;
1929 	req->wValue = cpu_to_le16(value);
1930 	req->wIndex = cpu_to_le16(index);
1931 	req->wLength = cpu_to_le16(size);
1932 
1933 	usb_fill_control_urb(urb, dev->udev,
1934 			     usb_sndctrlpipe(dev->udev, 0),
1935 			     (void *)req, buf, size,
1936 			     usbnet_async_cmd_cb, req);
1937 	urb->transfer_flags |= URB_FREE_BUFFER;
1938 
1939 	err = usb_submit_urb(urb, GFP_ATOMIC);
1940 	if (err < 0) {
1941 		netdev_err(dev->net, "Error submitting the control"
1942 			   " message: status=%d\n", err);
1943 		goto fail_free;
1944 	}
1945 	return 0;
1946 
1947 fail_free_buf:
1948 	kfree(buf);
1949 fail_free:
1950 	kfree(req);
1951 	usb_free_urb(urb);
1952 fail:
1953 	return err;
1954 
1955 }
1956 EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
1957 /*-------------------------------------------------------------------------*/
1958 
1959 static int __init usbnet_init(void)
1960 {
1961 	/* Compiler should optimize this out. */
1962 	BUILD_BUG_ON(
1963 		FIELD_SIZEOF(struct sk_buff, cb) < sizeof(struct skb_data));
1964 
1965 	eth_random_addr(node_id);
1966 	return 0;
1967 }
1968 module_init(usbnet_init);
1969 
1970 static void __exit usbnet_exit(void)
1971 {
1972 }
1973 module_exit(usbnet_exit);
1974 
1975 MODULE_AUTHOR("David Brownell");
1976 MODULE_DESCRIPTION("USB network driver framework");
1977 MODULE_LICENSE("GPL");
1978