xref: /linux/drivers/net/usb/usbnet.c (revision b7019ac550eb3916f34d79db583e9b7ea2524afa)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * USB Network driver infrastructure
4  * Copyright (C) 2000-2005 by David Brownell
5  * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
6  */
7 
8 /*
9  * This is a generic "USB networking" framework that works with several
10  * kinds of full and high speed networking devices:  host-to-host cables,
11  * smart usb peripherals, and actual Ethernet adapters.
12  *
13  * These devices usually differ in terms of control protocols (if they
14  * even have one!) and sometimes they define new framing to wrap or batch
15  * Ethernet packets.  Otherwise, they talk to USB pretty much the same,
16  * so interface (un)binding, endpoint I/O queues, fault handling, and other
17  * issues can usefully be addressed by this framework.
18  */
19 
20 // #define	DEBUG			// error path messages, extra info
21 // #define	VERBOSE			// more; success messages
22 
23 #include <linux/module.h>
24 #include <linux/init.h>
25 #include <linux/netdevice.h>
26 #include <linux/etherdevice.h>
27 #include <linux/ctype.h>
28 #include <linux/ethtool.h>
29 #include <linux/workqueue.h>
30 #include <linux/mii.h>
31 #include <linux/usb.h>
32 #include <linux/usb/usbnet.h>
33 #include <linux/slab.h>
34 #include <linux/kernel.h>
35 #include <linux/pm_runtime.h>
36 
37 #define DRIVER_VERSION		"22-Aug-2005"
38 
39 
40 /*-------------------------------------------------------------------------*/
41 
42 /*
43  * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
44  * Several dozen bytes of IPv4 data can fit in two such transactions.
45  * One maximum size Ethernet packet takes twenty four of them.
46  * For high speed, each frame comfortably fits almost 36 max size
47  * Ethernet packets (so queues should be bigger).
48  *
49  * The goal is to let the USB host controller be busy for 5msec or
50  * more before an irq is required, under load.  Jumbograms change
51  * the equation.
52  */
53 #define	MAX_QUEUE_MEMORY	(60 * 1518)
54 #define	RX_QLEN(dev)		((dev)->rx_qlen)
55 #define	TX_QLEN(dev)		((dev)->tx_qlen)
56 
57 // reawaken network queue this soon after stopping; else watchdog barks
58 #define TX_TIMEOUT_JIFFIES	(5*HZ)
59 
60 /* throttle rx/tx briefly after some faults, so hub_wq might disconnect()
61  * us (it polls at HZ/4 usually) before we report too many false errors.
62  */
63 #define THROTTLE_JIFFIES	(HZ/8)
64 
65 // between wakeups
66 #define UNLINK_TIMEOUT_MS	3
67 
68 /*-------------------------------------------------------------------------*/
69 
70 // randomly generated ethernet address
71 static u8	node_id [ETH_ALEN];
72 
73 /* use ethtool to change the level for any given device */
74 static int msg_level = -1;
75 module_param (msg_level, int, 0);
76 MODULE_PARM_DESC (msg_level, "Override default message level");
77 
78 /*-------------------------------------------------------------------------*/
79 
80 /* handles CDC Ethernet and many other network "bulk data" interfaces */
81 int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
82 {
83 	int				tmp;
84 	struct usb_host_interface	*alt = NULL;
85 	struct usb_host_endpoint	*in = NULL, *out = NULL;
86 	struct usb_host_endpoint	*status = NULL;
87 
88 	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
89 		unsigned	ep;
90 
91 		in = out = status = NULL;
92 		alt = intf->altsetting + tmp;
93 
94 		/* take the first altsetting with in-bulk + out-bulk;
95 		 * remember any status endpoint, just in case;
96 		 * ignore other endpoints and altsettings.
97 		 */
98 		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
99 			struct usb_host_endpoint	*e;
100 			int				intr = 0;
101 
102 			e = alt->endpoint + ep;
103 			switch (e->desc.bmAttributes) {
104 			case USB_ENDPOINT_XFER_INT:
105 				if (!usb_endpoint_dir_in(&e->desc))
106 					continue;
107 				intr = 1;
108 				/* FALLTHROUGH */
109 			case USB_ENDPOINT_XFER_BULK:
110 				break;
111 			default:
112 				continue;
113 			}
114 			if (usb_endpoint_dir_in(&e->desc)) {
115 				if (!intr && !in)
116 					in = e;
117 				else if (intr && !status)
118 					status = e;
119 			} else {
120 				if (!out)
121 					out = e;
122 			}
123 		}
124 		if (in && out)
125 			break;
126 	}
127 	if (!alt || !in || !out)
128 		return -EINVAL;
129 
130 	if (alt->desc.bAlternateSetting != 0 ||
131 	    !(dev->driver_info->flags & FLAG_NO_SETINT)) {
132 		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
133 				alt->desc.bAlternateSetting);
134 		if (tmp < 0)
135 			return tmp;
136 	}
137 
138 	dev->in = usb_rcvbulkpipe (dev->udev,
139 			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
140 	dev->out = usb_sndbulkpipe (dev->udev,
141 			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
142 	dev->status = status;
143 	return 0;
144 }
145 EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
146 
147 int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
148 {
149 	int 		tmp = -1, ret;
150 	unsigned char	buf [13];
151 
152 	ret = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
153 	if (ret == 12)
154 		tmp = hex2bin(dev->net->dev_addr, buf, 6);
155 	if (tmp < 0) {
156 		dev_dbg(&dev->udev->dev,
157 			"bad MAC string %d fetch, %d\n", iMACAddress, tmp);
158 		if (ret >= 0)
159 			ret = -EINVAL;
160 		return ret;
161 	}
162 	return 0;
163 }
164 EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
165 
166 static void intr_complete (struct urb *urb)
167 {
168 	struct usbnet	*dev = urb->context;
169 	int		status = urb->status;
170 
171 	switch (status) {
172 	/* success */
173 	case 0:
174 		dev->driver_info->status(dev, urb);
175 		break;
176 
177 	/* software-driven interface shutdown */
178 	case -ENOENT:		/* urb killed */
179 	case -ESHUTDOWN:	/* hardware gone */
180 		netif_dbg(dev, ifdown, dev->net,
181 			  "intr shutdown, code %d\n", status);
182 		return;
183 
184 	/* NOTE:  not throttling like RX/TX, since this endpoint
185 	 * already polls infrequently
186 	 */
187 	default:
188 		netdev_dbg(dev->net, "intr status %d\n", status);
189 		break;
190 	}
191 
192 	status = usb_submit_urb (urb, GFP_ATOMIC);
193 	if (status != 0)
194 		netif_err(dev, timer, dev->net,
195 			  "intr resubmit --> %d\n", status);
196 }
197 
198 static int init_status (struct usbnet *dev, struct usb_interface *intf)
199 {
200 	char		*buf = NULL;
201 	unsigned	pipe = 0;
202 	unsigned	maxp;
203 	unsigned	period;
204 
205 	if (!dev->driver_info->status)
206 		return 0;
207 
208 	pipe = usb_rcvintpipe (dev->udev,
209 			dev->status->desc.bEndpointAddress
210 				& USB_ENDPOINT_NUMBER_MASK);
211 	maxp = usb_maxpacket (dev->udev, pipe, 0);
212 
213 	/* avoid 1 msec chatter:  min 8 msec poll rate */
214 	period = max ((int) dev->status->desc.bInterval,
215 		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
216 
217 	buf = kmalloc (maxp, GFP_KERNEL);
218 	if (buf) {
219 		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
220 		if (!dev->interrupt) {
221 			kfree (buf);
222 			return -ENOMEM;
223 		} else {
224 			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
225 				buf, maxp, intr_complete, dev, period);
226 			dev->interrupt->transfer_flags |= URB_FREE_BUFFER;
227 			dev_dbg(&intf->dev,
228 				"status ep%din, %d bytes period %d\n",
229 				usb_pipeendpoint(pipe), maxp, period);
230 		}
231 	}
232 	return 0;
233 }
234 
235 /* Submit the interrupt URB if not previously submitted, increasing refcount */
236 int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
237 {
238 	int ret = 0;
239 
240 	WARN_ON_ONCE(dev->interrupt == NULL);
241 	if (dev->interrupt) {
242 		mutex_lock(&dev->interrupt_mutex);
243 
244 		if (++dev->interrupt_count == 1)
245 			ret = usb_submit_urb(dev->interrupt, mem_flags);
246 
247 		dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d\n",
248 			dev->interrupt_count);
249 		mutex_unlock(&dev->interrupt_mutex);
250 	}
251 	return ret;
252 }
253 EXPORT_SYMBOL_GPL(usbnet_status_start);
254 
255 /* For resume; submit interrupt URB if previously submitted */
256 static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
257 {
258 	int ret = 0;
259 
260 	mutex_lock(&dev->interrupt_mutex);
261 	if (dev->interrupt_count) {
262 		ret = usb_submit_urb(dev->interrupt, mem_flags);
263 		dev_dbg(&dev->udev->dev,
264 			"submitted interrupt URB for resume\n");
265 	}
266 	mutex_unlock(&dev->interrupt_mutex);
267 	return ret;
268 }
269 
270 /* Kill the interrupt URB if all submitters want it killed */
271 void usbnet_status_stop(struct usbnet *dev)
272 {
273 	if (dev->interrupt) {
274 		mutex_lock(&dev->interrupt_mutex);
275 		WARN_ON(dev->interrupt_count == 0);
276 
277 		if (dev->interrupt_count && --dev->interrupt_count == 0)
278 			usb_kill_urb(dev->interrupt);
279 
280 		dev_dbg(&dev->udev->dev,
281 			"decremented interrupt URB count to %d\n",
282 			dev->interrupt_count);
283 		mutex_unlock(&dev->interrupt_mutex);
284 	}
285 }
286 EXPORT_SYMBOL_GPL(usbnet_status_stop);
287 
288 /* For suspend; always kill interrupt URB */
289 static void __usbnet_status_stop_force(struct usbnet *dev)
290 {
291 	if (dev->interrupt) {
292 		mutex_lock(&dev->interrupt_mutex);
293 		usb_kill_urb(dev->interrupt);
294 		dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend\n");
295 		mutex_unlock(&dev->interrupt_mutex);
296 	}
297 }
298 
299 /* Passes this packet up the stack, updating its accounting.
300  * Some link protocols batch packets, so their rx_fixup paths
301  * can return clones as well as just modify the original skb.
302  */
303 void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
304 {
305 	struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->stats64);
306 	unsigned long flags;
307 	int	status;
308 
309 	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
310 		skb_queue_tail(&dev->rxq_pause, skb);
311 		return;
312 	}
313 
314 	/* only update if unset to allow minidriver rx_fixup override */
315 	if (skb->protocol == 0)
316 		skb->protocol = eth_type_trans (skb, dev->net);
317 
318 	flags = u64_stats_update_begin_irqsave(&stats64->syncp);
319 	stats64->rx_packets++;
320 	stats64->rx_bytes += skb->len;
321 	u64_stats_update_end_irqrestore(&stats64->syncp, flags);
322 
323 	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
324 		  skb->len + sizeof (struct ethhdr), skb->protocol);
325 	memset (skb->cb, 0, sizeof (struct skb_data));
326 
327 	if (skb_defer_rx_timestamp(skb))
328 		return;
329 
330 	status = netif_rx (skb);
331 	if (status != NET_RX_SUCCESS)
332 		netif_dbg(dev, rx_err, dev->net,
333 			  "netif_rx status %d\n", status);
334 }
335 EXPORT_SYMBOL_GPL(usbnet_skb_return);
336 
337 /* must be called if hard_mtu or rx_urb_size changed */
338 void usbnet_update_max_qlen(struct usbnet *dev)
339 {
340 	enum usb_device_speed speed = dev->udev->speed;
341 
342 	switch (speed) {
343 	case USB_SPEED_HIGH:
344 		dev->rx_qlen = MAX_QUEUE_MEMORY / dev->rx_urb_size;
345 		dev->tx_qlen = MAX_QUEUE_MEMORY / dev->hard_mtu;
346 		break;
347 	case USB_SPEED_SUPER:
348 	case USB_SPEED_SUPER_PLUS:
349 		/*
350 		 * Not take default 5ms qlen for super speed HC to
351 		 * save memory, and iperf tests show 2.5ms qlen can
352 		 * work well
353 		 */
354 		dev->rx_qlen = 5 * MAX_QUEUE_MEMORY / dev->rx_urb_size;
355 		dev->tx_qlen = 5 * MAX_QUEUE_MEMORY / dev->hard_mtu;
356 		break;
357 	default:
358 		dev->rx_qlen = dev->tx_qlen = 4;
359 	}
360 }
361 EXPORT_SYMBOL_GPL(usbnet_update_max_qlen);
362 
363 
364 /*-------------------------------------------------------------------------
365  *
366  * Network Device Driver (peer link to "Host Device", from USB host)
367  *
368  *-------------------------------------------------------------------------*/
369 
370 int usbnet_change_mtu (struct net_device *net, int new_mtu)
371 {
372 	struct usbnet	*dev = netdev_priv(net);
373 	int		ll_mtu = new_mtu + net->hard_header_len;
374 	int		old_hard_mtu = dev->hard_mtu;
375 	int		old_rx_urb_size = dev->rx_urb_size;
376 
377 	// no second zero-length packet read wanted after mtu-sized packets
378 	if ((ll_mtu % dev->maxpacket) == 0)
379 		return -EDOM;
380 	net->mtu = new_mtu;
381 
382 	dev->hard_mtu = net->mtu + net->hard_header_len;
383 	if (dev->rx_urb_size == old_hard_mtu) {
384 		dev->rx_urb_size = dev->hard_mtu;
385 		if (dev->rx_urb_size > old_rx_urb_size) {
386 			usbnet_pause_rx(dev);
387 			usbnet_unlink_rx_urbs(dev);
388 			usbnet_resume_rx(dev);
389 		}
390 	}
391 
392 	/* max qlen depend on hard_mtu and rx_urb_size */
393 	usbnet_update_max_qlen(dev);
394 
395 	return 0;
396 }
397 EXPORT_SYMBOL_GPL(usbnet_change_mtu);
398 
399 /* The caller must hold list->lock */
400 static void __usbnet_queue_skb(struct sk_buff_head *list,
401 			struct sk_buff *newsk, enum skb_state state)
402 {
403 	struct skb_data *entry = (struct skb_data *) newsk->cb;
404 
405 	__skb_queue_tail(list, newsk);
406 	entry->state = state;
407 }
408 
409 /*-------------------------------------------------------------------------*/
410 
411 /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
412  * completion callbacks.  2.5 should have fixed those bugs...
413  */
414 
415 static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
416 		struct sk_buff_head *list, enum skb_state state)
417 {
418 	unsigned long		flags;
419 	enum skb_state 		old_state;
420 	struct skb_data *entry = (struct skb_data *) skb->cb;
421 
422 	spin_lock_irqsave(&list->lock, flags);
423 	old_state = entry->state;
424 	entry->state = state;
425 	__skb_unlink(skb, list);
426 
427 	/* defer_bh() is never called with list == &dev->done.
428 	 * spin_lock_nested() tells lockdep that it is OK to take
429 	 * dev->done.lock here with list->lock held.
430 	 */
431 	spin_lock_nested(&dev->done.lock, SINGLE_DEPTH_NESTING);
432 
433 	__skb_queue_tail(&dev->done, skb);
434 	if (dev->done.qlen == 1)
435 		tasklet_schedule(&dev->bh);
436 	spin_unlock(&dev->done.lock);
437 	spin_unlock_irqrestore(&list->lock, flags);
438 	return old_state;
439 }
440 
441 /* some work can't be done in tasklets, so we use keventd
442  *
443  * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
444  * but tasklet_schedule() doesn't.  hope the failure is rare.
445  */
446 void usbnet_defer_kevent (struct usbnet *dev, int work)
447 {
448 	set_bit (work, &dev->flags);
449 	if (!schedule_work (&dev->kevent))
450 		netdev_dbg(dev->net, "kevent %d may have been dropped\n", work);
451 	else
452 		netdev_dbg(dev->net, "kevent %d scheduled\n", work);
453 }
454 EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
455 
456 /*-------------------------------------------------------------------------*/
457 
458 static void rx_complete (struct urb *urb);
459 
460 static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
461 {
462 	struct sk_buff		*skb;
463 	struct skb_data		*entry;
464 	int			retval = 0;
465 	unsigned long		lockflags;
466 	size_t			size = dev->rx_urb_size;
467 
468 	/* prevent rx skb allocation when error ratio is high */
469 	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
470 		usb_free_urb(urb);
471 		return -ENOLINK;
472 	}
473 
474 	if (test_bit(EVENT_NO_IP_ALIGN, &dev->flags))
475 		skb = __netdev_alloc_skb(dev->net, size, flags);
476 	else
477 		skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
478 	if (!skb) {
479 		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
480 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
481 		usb_free_urb (urb);
482 		return -ENOMEM;
483 	}
484 
485 	entry = (struct skb_data *) skb->cb;
486 	entry->urb = urb;
487 	entry->dev = dev;
488 	entry->length = 0;
489 
490 	usb_fill_bulk_urb (urb, dev->udev, dev->in,
491 		skb->data, size, rx_complete, skb);
492 
493 	spin_lock_irqsave (&dev->rxq.lock, lockflags);
494 
495 	if (netif_running (dev->net) &&
496 	    netif_device_present (dev->net) &&
497 	    test_bit(EVENT_DEV_OPEN, &dev->flags) &&
498 	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
499 	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
500 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
501 		case -EPIPE:
502 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
503 			break;
504 		case -ENOMEM:
505 			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
506 			break;
507 		case -ENODEV:
508 			netif_dbg(dev, ifdown, dev->net, "device gone\n");
509 			netif_device_detach (dev->net);
510 			break;
511 		case -EHOSTUNREACH:
512 			retval = -ENOLINK;
513 			break;
514 		default:
515 			netif_dbg(dev, rx_err, dev->net,
516 				  "rx submit, %d\n", retval);
517 			tasklet_schedule (&dev->bh);
518 			break;
519 		case 0:
520 			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
521 		}
522 	} else {
523 		netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
524 		retval = -ENOLINK;
525 	}
526 	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
527 	if (retval) {
528 		dev_kfree_skb_any (skb);
529 		usb_free_urb (urb);
530 	}
531 	return retval;
532 }
533 
534 
535 /*-------------------------------------------------------------------------*/
536 
537 static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
538 {
539 	if (dev->driver_info->rx_fixup &&
540 	    !dev->driver_info->rx_fixup (dev, skb)) {
541 		/* With RX_ASSEMBLE, rx_fixup() must update counters */
542 		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
543 			dev->net->stats.rx_errors++;
544 		goto done;
545 	}
546 	// else network stack removes extra byte if we forced a short packet
547 
548 	/* all data was already cloned from skb inside the driver */
549 	if (dev->driver_info->flags & FLAG_MULTI_PACKET)
550 		goto done;
551 
552 	if (skb->len < ETH_HLEN) {
553 		dev->net->stats.rx_errors++;
554 		dev->net->stats.rx_length_errors++;
555 		netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len);
556 	} else {
557 		usbnet_skb_return(dev, skb);
558 		return;
559 	}
560 
561 done:
562 	skb_queue_tail(&dev->done, skb);
563 }
564 
565 /*-------------------------------------------------------------------------*/
566 
567 static void rx_complete (struct urb *urb)
568 {
569 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
570 	struct skb_data		*entry = (struct skb_data *) skb->cb;
571 	struct usbnet		*dev = entry->dev;
572 	int			urb_status = urb->status;
573 	enum skb_state		state;
574 
575 	skb_put (skb, urb->actual_length);
576 	state = rx_done;
577 	entry->urb = NULL;
578 
579 	switch (urb_status) {
580 	/* success */
581 	case 0:
582 		break;
583 
584 	/* stalls need manual reset. this is rare ... except that
585 	 * when going through USB 2.0 TTs, unplug appears this way.
586 	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
587 	 * storm, recovering as needed.
588 	 */
589 	case -EPIPE:
590 		dev->net->stats.rx_errors++;
591 		usbnet_defer_kevent (dev, EVENT_RX_HALT);
592 		// FALLTHROUGH
593 
594 	/* software-driven interface shutdown */
595 	case -ECONNRESET:		/* async unlink */
596 	case -ESHUTDOWN:		/* hardware gone */
597 		netif_dbg(dev, ifdown, dev->net,
598 			  "rx shutdown, code %d\n", urb_status);
599 		goto block;
600 
601 	/* we get controller i/o faults during hub_wq disconnect() delays.
602 	 * throttle down resubmits, to avoid log floods; just temporarily,
603 	 * so we still recover when the fault isn't a hub_wq delay.
604 	 */
605 	case -EPROTO:
606 	case -ETIME:
607 	case -EILSEQ:
608 		dev->net->stats.rx_errors++;
609 		if (!timer_pending (&dev->delay)) {
610 			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
611 			netif_dbg(dev, link, dev->net,
612 				  "rx throttle %d\n", urb_status);
613 		}
614 block:
615 		state = rx_cleanup;
616 		entry->urb = urb;
617 		urb = NULL;
618 		break;
619 
620 	/* data overrun ... flush fifo? */
621 	case -EOVERFLOW:
622 		dev->net->stats.rx_over_errors++;
623 		// FALLTHROUGH
624 
625 	default:
626 		state = rx_cleanup;
627 		dev->net->stats.rx_errors++;
628 		netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
629 		break;
630 	}
631 
632 	/* stop rx if packet error rate is high */
633 	if (++dev->pkt_cnt > 30) {
634 		dev->pkt_cnt = 0;
635 		dev->pkt_err = 0;
636 	} else {
637 		if (state == rx_cleanup)
638 			dev->pkt_err++;
639 		if (dev->pkt_err > 20)
640 			set_bit(EVENT_RX_KILL, &dev->flags);
641 	}
642 
643 	state = defer_bh(dev, skb, &dev->rxq, state);
644 
645 	if (urb) {
646 		if (netif_running (dev->net) &&
647 		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
648 		    state != unlink_start) {
649 			rx_submit (dev, urb, GFP_ATOMIC);
650 			usb_mark_last_busy(dev->udev);
651 			return;
652 		}
653 		usb_free_urb (urb);
654 	}
655 	netif_dbg(dev, rx_err, dev->net, "no read resubmitted\n");
656 }
657 
658 /*-------------------------------------------------------------------------*/
659 void usbnet_pause_rx(struct usbnet *dev)
660 {
661 	set_bit(EVENT_RX_PAUSED, &dev->flags);
662 
663 	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled\n");
664 }
665 EXPORT_SYMBOL_GPL(usbnet_pause_rx);
666 
667 void usbnet_resume_rx(struct usbnet *dev)
668 {
669 	struct sk_buff *skb;
670 	int num = 0;
671 
672 	clear_bit(EVENT_RX_PAUSED, &dev->flags);
673 
674 	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
675 		usbnet_skb_return(dev, skb);
676 		num++;
677 	}
678 
679 	tasklet_schedule(&dev->bh);
680 
681 	netif_dbg(dev, rx_status, dev->net,
682 		  "paused rx queue disabled, %d skbs requeued\n", num);
683 }
684 EXPORT_SYMBOL_GPL(usbnet_resume_rx);
685 
686 void usbnet_purge_paused_rxq(struct usbnet *dev)
687 {
688 	skb_queue_purge(&dev->rxq_pause);
689 }
690 EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
691 
692 /*-------------------------------------------------------------------------*/
693 
694 // unlink pending rx/tx; completion handlers do all other cleanup
695 
696 static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
697 {
698 	unsigned long		flags;
699 	struct sk_buff		*skb;
700 	int			count = 0;
701 
702 	spin_lock_irqsave (&q->lock, flags);
703 	while (!skb_queue_empty(q)) {
704 		struct skb_data		*entry;
705 		struct urb		*urb;
706 		int			retval;
707 
708 		skb_queue_walk(q, skb) {
709 			entry = (struct skb_data *) skb->cb;
710 			if (entry->state != unlink_start)
711 				goto found;
712 		}
713 		break;
714 found:
715 		entry->state = unlink_start;
716 		urb = entry->urb;
717 
718 		/*
719 		 * Get reference count of the URB to avoid it to be
720 		 * freed during usb_unlink_urb, which may trigger
721 		 * use-after-free problem inside usb_unlink_urb since
722 		 * usb_unlink_urb is always racing with .complete
723 		 * handler(include defer_bh).
724 		 */
725 		usb_get_urb(urb);
726 		spin_unlock_irqrestore(&q->lock, flags);
727 		// during some PM-driven resume scenarios,
728 		// these (async) unlinks complete immediately
729 		retval = usb_unlink_urb (urb);
730 		if (retval != -EINPROGRESS && retval != 0)
731 			netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
732 		else
733 			count++;
734 		usb_put_urb(urb);
735 		spin_lock_irqsave(&q->lock, flags);
736 	}
737 	spin_unlock_irqrestore (&q->lock, flags);
738 	return count;
739 }
740 
741 // Flush all pending rx urbs
742 // minidrivers may need to do this when the MTU changes
743 
744 void usbnet_unlink_rx_urbs(struct usbnet *dev)
745 {
746 	if (netif_running(dev->net)) {
747 		(void) unlink_urbs (dev, &dev->rxq);
748 		tasklet_schedule(&dev->bh);
749 	}
750 }
751 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
752 
753 /*-------------------------------------------------------------------------*/
754 
755 static void wait_skb_queue_empty(struct sk_buff_head *q)
756 {
757 	unsigned long flags;
758 
759 	spin_lock_irqsave(&q->lock, flags);
760 	while (!skb_queue_empty(q)) {
761 		spin_unlock_irqrestore(&q->lock, flags);
762 		schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
763 		set_current_state(TASK_UNINTERRUPTIBLE);
764 		spin_lock_irqsave(&q->lock, flags);
765 	}
766 	spin_unlock_irqrestore(&q->lock, flags);
767 }
768 
769 // precondition: never called in_interrupt
770 static void usbnet_terminate_urbs(struct usbnet *dev)
771 {
772 	DECLARE_WAITQUEUE(wait, current);
773 	int temp;
774 
775 	/* ensure there are no more active urbs */
776 	add_wait_queue(&dev->wait, &wait);
777 	set_current_state(TASK_UNINTERRUPTIBLE);
778 	temp = unlink_urbs(dev, &dev->txq) +
779 		unlink_urbs(dev, &dev->rxq);
780 
781 	/* maybe wait for deletions to finish. */
782 	wait_skb_queue_empty(&dev->rxq);
783 	wait_skb_queue_empty(&dev->txq);
784 	wait_skb_queue_empty(&dev->done);
785 	netif_dbg(dev, ifdown, dev->net,
786 		  "waited for %d urb completions\n", temp);
787 	set_current_state(TASK_RUNNING);
788 	remove_wait_queue(&dev->wait, &wait);
789 }
790 
791 int usbnet_stop (struct net_device *net)
792 {
793 	struct usbnet		*dev = netdev_priv(net);
794 	const struct driver_info *info = dev->driver_info;
795 	int			retval, pm, mpn;
796 
797 	clear_bit(EVENT_DEV_OPEN, &dev->flags);
798 	netif_stop_queue (net);
799 
800 	netif_info(dev, ifdown, dev->net,
801 		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu\n",
802 		   net->stats.rx_packets, net->stats.tx_packets,
803 		   net->stats.rx_errors, net->stats.tx_errors);
804 
805 	/* to not race resume */
806 	pm = usb_autopm_get_interface(dev->intf);
807 	/* allow minidriver to stop correctly (wireless devices to turn off
808 	 * radio etc) */
809 	if (info->stop) {
810 		retval = info->stop(dev);
811 		if (retval < 0)
812 			netif_info(dev, ifdown, dev->net,
813 				   "stop fail (%d) usbnet usb-%s-%s, %s\n",
814 				   retval,
815 				   dev->udev->bus->bus_name, dev->udev->devpath,
816 				   info->description);
817 	}
818 
819 	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
820 		usbnet_terminate_urbs(dev);
821 
822 	usbnet_status_stop(dev);
823 
824 	usbnet_purge_paused_rxq(dev);
825 
826 	mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
827 
828 	/* deferred work (task, timer, softirq) must also stop.
829 	 * can't flush_scheduled_work() until we drop rtnl (later),
830 	 * else workers could deadlock; so make workers a NOP.
831 	 */
832 	dev->flags = 0;
833 	del_timer_sync (&dev->delay);
834 	tasklet_kill (&dev->bh);
835 	if (!pm)
836 		usb_autopm_put_interface(dev->intf);
837 
838 	if (info->manage_power && mpn)
839 		info->manage_power(dev, 0);
840 	else
841 		usb_autopm_put_interface(dev->intf);
842 
843 	return 0;
844 }
845 EXPORT_SYMBOL_GPL(usbnet_stop);
846 
847 /*-------------------------------------------------------------------------*/
848 
849 // posts reads, and enables write queuing
850 
851 // precondition: never called in_interrupt
852 
853 int usbnet_open (struct net_device *net)
854 {
855 	struct usbnet		*dev = netdev_priv(net);
856 	int			retval;
857 	const struct driver_info *info = dev->driver_info;
858 
859 	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
860 		netif_info(dev, ifup, dev->net,
861 			   "resumption fail (%d) usbnet usb-%s-%s, %s\n",
862 			   retval,
863 			   dev->udev->bus->bus_name,
864 			   dev->udev->devpath,
865 			   info->description);
866 		goto done_nopm;
867 	}
868 
869 	// put into "known safe" state
870 	if (info->reset && (retval = info->reset (dev)) < 0) {
871 		netif_info(dev, ifup, dev->net,
872 			   "open reset fail (%d) usbnet usb-%s-%s, %s\n",
873 			   retval,
874 			   dev->udev->bus->bus_name,
875 			   dev->udev->devpath,
876 			   info->description);
877 		goto done;
878 	}
879 
880 	/* hard_mtu or rx_urb_size may change in reset() */
881 	usbnet_update_max_qlen(dev);
882 
883 	// insist peer be connected
884 	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
885 		netif_dbg(dev, ifup, dev->net, "can't open; %d\n", retval);
886 		goto done;
887 	}
888 
889 	/* start any status interrupt transfer */
890 	if (dev->interrupt) {
891 		retval = usbnet_status_start(dev, GFP_KERNEL);
892 		if (retval < 0) {
893 			netif_err(dev, ifup, dev->net,
894 				  "intr submit %d\n", retval);
895 			goto done;
896 		}
897 	}
898 
899 	set_bit(EVENT_DEV_OPEN, &dev->flags);
900 	netif_start_queue (net);
901 	netif_info(dev, ifup, dev->net,
902 		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing\n",
903 		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
904 		   dev->net->mtu,
905 		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
906 		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
907 		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
908 		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
909 		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
910 		   "simple");
911 
912 	/* reset rx error state */
913 	dev->pkt_cnt = 0;
914 	dev->pkt_err = 0;
915 	clear_bit(EVENT_RX_KILL, &dev->flags);
916 
917 	// delay posting reads until we're fully open
918 	tasklet_schedule (&dev->bh);
919 	if (info->manage_power) {
920 		retval = info->manage_power(dev, 1);
921 		if (retval < 0) {
922 			retval = 0;
923 			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
924 		} else {
925 			usb_autopm_put_interface(dev->intf);
926 		}
927 	}
928 	return retval;
929 done:
930 	usb_autopm_put_interface(dev->intf);
931 done_nopm:
932 	return retval;
933 }
934 EXPORT_SYMBOL_GPL(usbnet_open);
935 
936 /*-------------------------------------------------------------------------*/
937 
938 /* ethtool methods; minidrivers may need to add some more, but
939  * they'll probably want to use this base set.
940  */
941 
942 int usbnet_get_link_ksettings(struct net_device *net,
943 			      struct ethtool_link_ksettings *cmd)
944 {
945 	struct usbnet *dev = netdev_priv(net);
946 
947 	if (!dev->mii.mdio_read)
948 		return -EOPNOTSUPP;
949 
950 	mii_ethtool_get_link_ksettings(&dev->mii, cmd);
951 
952 	return 0;
953 }
954 EXPORT_SYMBOL_GPL(usbnet_get_link_ksettings);
955 
956 int usbnet_set_link_ksettings(struct net_device *net,
957 			      const struct ethtool_link_ksettings *cmd)
958 {
959 	struct usbnet *dev = netdev_priv(net);
960 	int retval;
961 
962 	if (!dev->mii.mdio_write)
963 		return -EOPNOTSUPP;
964 
965 	retval = mii_ethtool_set_link_ksettings(&dev->mii, cmd);
966 
967 	/* link speed/duplex might have changed */
968 	if (dev->driver_info->link_reset)
969 		dev->driver_info->link_reset(dev);
970 
971 	/* hard_mtu or rx_urb_size may change in link_reset() */
972 	usbnet_update_max_qlen(dev);
973 
974 	return retval;
975 }
976 EXPORT_SYMBOL_GPL(usbnet_set_link_ksettings);
977 
978 void usbnet_get_stats64(struct net_device *net, struct rtnl_link_stats64 *stats)
979 {
980 	struct usbnet *dev = netdev_priv(net);
981 	unsigned int start;
982 	int cpu;
983 
984 	netdev_stats_to_stats64(stats, &net->stats);
985 
986 	for_each_possible_cpu(cpu) {
987 		struct pcpu_sw_netstats *stats64;
988 		u64 rx_packets, rx_bytes;
989 		u64 tx_packets, tx_bytes;
990 
991 		stats64 = per_cpu_ptr(dev->stats64, cpu);
992 
993 		do {
994 			start = u64_stats_fetch_begin_irq(&stats64->syncp);
995 			rx_packets = stats64->rx_packets;
996 			rx_bytes = stats64->rx_bytes;
997 			tx_packets = stats64->tx_packets;
998 			tx_bytes = stats64->tx_bytes;
999 		} while (u64_stats_fetch_retry_irq(&stats64->syncp, start));
1000 
1001 		stats->rx_packets += rx_packets;
1002 		stats->rx_bytes += rx_bytes;
1003 		stats->tx_packets += tx_packets;
1004 		stats->tx_bytes += tx_bytes;
1005 	}
1006 }
1007 EXPORT_SYMBOL_GPL(usbnet_get_stats64);
1008 
1009 u32 usbnet_get_link (struct net_device *net)
1010 {
1011 	struct usbnet *dev = netdev_priv(net);
1012 
1013 	/* If a check_connect is defined, return its result */
1014 	if (dev->driver_info->check_connect)
1015 		return dev->driver_info->check_connect (dev) == 0;
1016 
1017 	/* if the device has mii operations, use those */
1018 	if (dev->mii.mdio_read)
1019 		return mii_link_ok(&dev->mii);
1020 
1021 	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
1022 	return ethtool_op_get_link(net);
1023 }
1024 EXPORT_SYMBOL_GPL(usbnet_get_link);
1025 
1026 int usbnet_nway_reset(struct net_device *net)
1027 {
1028 	struct usbnet *dev = netdev_priv(net);
1029 
1030 	if (!dev->mii.mdio_write)
1031 		return -EOPNOTSUPP;
1032 
1033 	return mii_nway_restart(&dev->mii);
1034 }
1035 EXPORT_SYMBOL_GPL(usbnet_nway_reset);
1036 
1037 void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
1038 {
1039 	struct usbnet *dev = netdev_priv(net);
1040 
1041 	strlcpy (info->driver, dev->driver_name, sizeof info->driver);
1042 	strlcpy (info->version, DRIVER_VERSION, sizeof info->version);
1043 	strlcpy (info->fw_version, dev->driver_info->description,
1044 		sizeof info->fw_version);
1045 	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
1046 }
1047 EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
1048 
1049 u32 usbnet_get_msglevel (struct net_device *net)
1050 {
1051 	struct usbnet *dev = netdev_priv(net);
1052 
1053 	return dev->msg_enable;
1054 }
1055 EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
1056 
1057 void usbnet_set_msglevel (struct net_device *net, u32 level)
1058 {
1059 	struct usbnet *dev = netdev_priv(net);
1060 
1061 	dev->msg_enable = level;
1062 }
1063 EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
1064 
1065 /* drivers may override default ethtool_ops in their bind() routine */
1066 static const struct ethtool_ops usbnet_ethtool_ops = {
1067 	.get_link		= usbnet_get_link,
1068 	.nway_reset		= usbnet_nway_reset,
1069 	.get_drvinfo		= usbnet_get_drvinfo,
1070 	.get_msglevel		= usbnet_get_msglevel,
1071 	.set_msglevel		= usbnet_set_msglevel,
1072 	.get_ts_info		= ethtool_op_get_ts_info,
1073 	.get_link_ksettings	= usbnet_get_link_ksettings,
1074 	.set_link_ksettings	= usbnet_set_link_ksettings,
1075 };
1076 
1077 /*-------------------------------------------------------------------------*/
1078 
1079 static void __handle_link_change(struct usbnet *dev)
1080 {
1081 	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
1082 		return;
1083 
1084 	if (!netif_carrier_ok(dev->net)) {
1085 		/* kill URBs for reading packets to save bus bandwidth */
1086 		unlink_urbs(dev, &dev->rxq);
1087 
1088 		/*
1089 		 * tx_timeout will unlink URBs for sending packets and
1090 		 * tx queue is stopped by netcore after link becomes off
1091 		 */
1092 	} else {
1093 		/* submitting URBs for reading packets */
1094 		tasklet_schedule(&dev->bh);
1095 	}
1096 
1097 	/* hard_mtu or rx_urb_size may change during link change */
1098 	usbnet_update_max_qlen(dev);
1099 
1100 	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
1101 }
1102 
1103 static void usbnet_set_rx_mode(struct net_device *net)
1104 {
1105 	struct usbnet		*dev = netdev_priv(net);
1106 
1107 	usbnet_defer_kevent(dev, EVENT_SET_RX_MODE);
1108 }
1109 
1110 static void __handle_set_rx_mode(struct usbnet *dev)
1111 {
1112 	if (dev->driver_info->set_rx_mode)
1113 		(dev->driver_info->set_rx_mode)(dev);
1114 
1115 	clear_bit(EVENT_SET_RX_MODE, &dev->flags);
1116 }
1117 
1118 /* work that cannot be done in interrupt context uses keventd.
1119  *
1120  * NOTE:  with 2.5 we could do more of this using completion callbacks,
1121  * especially now that control transfers can be queued.
1122  */
1123 static void
1124 usbnet_deferred_kevent (struct work_struct *work)
1125 {
1126 	struct usbnet		*dev =
1127 		container_of(work, struct usbnet, kevent);
1128 	int			status;
1129 
1130 	/* usb_clear_halt() needs a thread context */
1131 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
1132 		unlink_urbs (dev, &dev->txq);
1133 		status = usb_autopm_get_interface(dev->intf);
1134 		if (status < 0)
1135 			goto fail_pipe;
1136 		status = usb_clear_halt (dev->udev, dev->out);
1137 		usb_autopm_put_interface(dev->intf);
1138 		if (status < 0 &&
1139 		    status != -EPIPE &&
1140 		    status != -ESHUTDOWN) {
1141 			if (netif_msg_tx_err (dev))
1142 fail_pipe:
1143 				netdev_err(dev->net, "can't clear tx halt, status %d\n",
1144 					   status);
1145 		} else {
1146 			clear_bit (EVENT_TX_HALT, &dev->flags);
1147 			if (status != -ESHUTDOWN)
1148 				netif_wake_queue (dev->net);
1149 		}
1150 	}
1151 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
1152 		unlink_urbs (dev, &dev->rxq);
1153 		status = usb_autopm_get_interface(dev->intf);
1154 		if (status < 0)
1155 			goto fail_halt;
1156 		status = usb_clear_halt (dev->udev, dev->in);
1157 		usb_autopm_put_interface(dev->intf);
1158 		if (status < 0 &&
1159 		    status != -EPIPE &&
1160 		    status != -ESHUTDOWN) {
1161 			if (netif_msg_rx_err (dev))
1162 fail_halt:
1163 				netdev_err(dev->net, "can't clear rx halt, status %d\n",
1164 					   status);
1165 		} else {
1166 			clear_bit (EVENT_RX_HALT, &dev->flags);
1167 			tasklet_schedule (&dev->bh);
1168 		}
1169 	}
1170 
1171 	/* tasklet could resubmit itself forever if memory is tight */
1172 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
1173 		struct urb	*urb = NULL;
1174 		int resched = 1;
1175 
1176 		if (netif_running (dev->net))
1177 			urb = usb_alloc_urb (0, GFP_KERNEL);
1178 		else
1179 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1180 		if (urb != NULL) {
1181 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1182 			status = usb_autopm_get_interface(dev->intf);
1183 			if (status < 0) {
1184 				usb_free_urb(urb);
1185 				goto fail_lowmem;
1186 			}
1187 			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
1188 				resched = 0;
1189 			usb_autopm_put_interface(dev->intf);
1190 fail_lowmem:
1191 			if (resched)
1192 				tasklet_schedule (&dev->bh);
1193 		}
1194 	}
1195 
1196 	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
1197 		const struct driver_info *info = dev->driver_info;
1198 		int			retval = 0;
1199 
1200 		clear_bit (EVENT_LINK_RESET, &dev->flags);
1201 		status = usb_autopm_get_interface(dev->intf);
1202 		if (status < 0)
1203 			goto skip_reset;
1204 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
1205 			usb_autopm_put_interface(dev->intf);
1206 skip_reset:
1207 			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s\n",
1208 				    retval,
1209 				    dev->udev->bus->bus_name,
1210 				    dev->udev->devpath,
1211 				    info->description);
1212 		} else {
1213 			usb_autopm_put_interface(dev->intf);
1214 		}
1215 
1216 		/* handle link change from link resetting */
1217 		__handle_link_change(dev);
1218 	}
1219 
1220 	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
1221 		__handle_link_change(dev);
1222 
1223 	if (test_bit (EVENT_SET_RX_MODE, &dev->flags))
1224 		__handle_set_rx_mode(dev);
1225 
1226 
1227 	if (dev->flags)
1228 		netdev_dbg(dev->net, "kevent done, flags = 0x%lx\n", dev->flags);
1229 }
1230 
1231 /*-------------------------------------------------------------------------*/
1232 
1233 static void tx_complete (struct urb *urb)
1234 {
1235 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
1236 	struct skb_data		*entry = (struct skb_data *) skb->cb;
1237 	struct usbnet		*dev = entry->dev;
1238 
1239 	if (urb->status == 0) {
1240 		struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->stats64);
1241 		unsigned long flags;
1242 
1243 		flags = u64_stats_update_begin_irqsave(&stats64->syncp);
1244 		stats64->tx_packets += entry->packets;
1245 		stats64->tx_bytes += entry->length;
1246 		u64_stats_update_end_irqrestore(&stats64->syncp, flags);
1247 	} else {
1248 		dev->net->stats.tx_errors++;
1249 
1250 		switch (urb->status) {
1251 		case -EPIPE:
1252 			usbnet_defer_kevent (dev, EVENT_TX_HALT);
1253 			break;
1254 
1255 		/* software-driven interface shutdown */
1256 		case -ECONNRESET:		// async unlink
1257 		case -ESHUTDOWN:		// hardware gone
1258 			break;
1259 
1260 		/* like rx, tx gets controller i/o faults during hub_wq
1261 		 * delays and so it uses the same throttling mechanism.
1262 		 */
1263 		case -EPROTO:
1264 		case -ETIME:
1265 		case -EILSEQ:
1266 			usb_mark_last_busy(dev->udev);
1267 			if (!timer_pending (&dev->delay)) {
1268 				mod_timer (&dev->delay,
1269 					jiffies + THROTTLE_JIFFIES);
1270 				netif_dbg(dev, link, dev->net,
1271 					  "tx throttle %d\n", urb->status);
1272 			}
1273 			netif_stop_queue (dev->net);
1274 			break;
1275 		default:
1276 			netif_dbg(dev, tx_err, dev->net,
1277 				  "tx err %d\n", entry->urb->status);
1278 			break;
1279 		}
1280 	}
1281 
1282 	usb_autopm_put_interface_async(dev->intf);
1283 	(void) defer_bh(dev, skb, &dev->txq, tx_done);
1284 }
1285 
1286 /*-------------------------------------------------------------------------*/
1287 
1288 void usbnet_tx_timeout (struct net_device *net)
1289 {
1290 	struct usbnet		*dev = netdev_priv(net);
1291 
1292 	unlink_urbs (dev, &dev->txq);
1293 	tasklet_schedule (&dev->bh);
1294 	/* this needs to be handled individually because the generic layer
1295 	 * doesn't know what is sufficient and could not restore private
1296 	 * information if a remedy of an unconditional reset were used.
1297 	 */
1298 	if (dev->driver_info->recover)
1299 		(dev->driver_info->recover)(dev);
1300 }
1301 EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
1302 
1303 /*-------------------------------------------------------------------------*/
1304 
1305 static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
1306 {
1307 	unsigned num_sgs, total_len = 0;
1308 	int i, s = 0;
1309 
1310 	num_sgs = skb_shinfo(skb)->nr_frags + 1;
1311 	if (num_sgs == 1)
1312 		return 0;
1313 
1314 	/* reserve one for zero packet */
1315 	urb->sg = kmalloc_array(num_sgs + 1, sizeof(struct scatterlist),
1316 				GFP_ATOMIC);
1317 	if (!urb->sg)
1318 		return -ENOMEM;
1319 
1320 	urb->num_sgs = num_sgs;
1321 	sg_init_table(urb->sg, urb->num_sgs + 1);
1322 
1323 	sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb));
1324 	total_len += skb_headlen(skb);
1325 
1326 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1327 		struct skb_frag_struct *f = &skb_shinfo(skb)->frags[i];
1328 
1329 		total_len += skb_frag_size(f);
1330 		sg_set_page(&urb->sg[i + s], f->page.p, f->size,
1331 				f->page_offset);
1332 	}
1333 	urb->transfer_buffer_length = total_len;
1334 
1335 	return 1;
1336 }
1337 
1338 netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
1339 				     struct net_device *net)
1340 {
1341 	struct usbnet		*dev = netdev_priv(net);
1342 	unsigned int			length;
1343 	struct urb		*urb = NULL;
1344 	struct skb_data		*entry;
1345 	const struct driver_info *info = dev->driver_info;
1346 	unsigned long		flags;
1347 	int retval;
1348 
1349 	if (skb)
1350 		skb_tx_timestamp(skb);
1351 
1352 	// some devices want funky USB-level framing, for
1353 	// win32 driver (usually) and/or hardware quirks
1354 	if (info->tx_fixup) {
1355 		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
1356 		if (!skb) {
1357 			/* packet collected; minidriver waiting for more */
1358 			if (info->flags & FLAG_MULTI_PACKET)
1359 				goto not_drop;
1360 			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
1361 			goto drop;
1362 		}
1363 	}
1364 
1365 	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
1366 		netif_dbg(dev, tx_err, dev->net, "no urb\n");
1367 		goto drop;
1368 	}
1369 
1370 	entry = (struct skb_data *) skb->cb;
1371 	entry->urb = urb;
1372 	entry->dev = dev;
1373 
1374 	usb_fill_bulk_urb (urb, dev->udev, dev->out,
1375 			skb->data, skb->len, tx_complete, skb);
1376 	if (dev->can_dma_sg) {
1377 		if (build_dma_sg(skb, urb) < 0)
1378 			goto drop;
1379 	}
1380 	length = urb->transfer_buffer_length;
1381 
1382 	/* don't assume the hardware handles USB_ZERO_PACKET
1383 	 * NOTE:  strictly conforming cdc-ether devices should expect
1384 	 * the ZLP here, but ignore the one-byte packet.
1385 	 * NOTE2: CDC NCM specification is different from CDC ECM when
1386 	 * handling ZLP/short packets, so cdc_ncm driver will make short
1387 	 * packet itself if needed.
1388 	 */
1389 	if (length % dev->maxpacket == 0) {
1390 		if (!(info->flags & FLAG_SEND_ZLP)) {
1391 			if (!(info->flags & FLAG_MULTI_PACKET)) {
1392 				length++;
1393 				if (skb_tailroom(skb) && !urb->num_sgs) {
1394 					skb->data[skb->len] = 0;
1395 					__skb_put(skb, 1);
1396 				} else if (urb->num_sgs)
1397 					sg_set_buf(&urb->sg[urb->num_sgs++],
1398 							dev->padding_pkt, 1);
1399 			}
1400 		} else
1401 			urb->transfer_flags |= URB_ZERO_PACKET;
1402 	}
1403 	urb->transfer_buffer_length = length;
1404 
1405 	if (info->flags & FLAG_MULTI_PACKET) {
1406 		/* Driver has set number of packets and a length delta.
1407 		 * Calculate the complete length and ensure that it's
1408 		 * positive.
1409 		 */
1410 		entry->length += length;
1411 		if (WARN_ON_ONCE(entry->length <= 0))
1412 			entry->length = length;
1413 	} else {
1414 		usbnet_set_skb_tx_stats(skb, 1, length);
1415 	}
1416 
1417 	spin_lock_irqsave(&dev->txq.lock, flags);
1418 	retval = usb_autopm_get_interface_async(dev->intf);
1419 	if (retval < 0) {
1420 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1421 		goto drop;
1422 	}
1423 	if (netif_queue_stopped(net)) {
1424 		usb_autopm_put_interface_async(dev->intf);
1425 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1426 		goto drop;
1427 	}
1428 
1429 #ifdef CONFIG_PM
1430 	/* if this triggers the device is still a sleep */
1431 	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
1432 		/* transmission will be done in resume */
1433 		usb_anchor_urb(urb, &dev->deferred);
1434 		/* no use to process more packets */
1435 		netif_stop_queue(net);
1436 		usb_put_urb(urb);
1437 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1438 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
1439 		goto deferred;
1440 	}
1441 #endif
1442 
1443 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
1444 	case -EPIPE:
1445 		netif_stop_queue (net);
1446 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
1447 		usb_autopm_put_interface_async(dev->intf);
1448 		break;
1449 	default:
1450 		usb_autopm_put_interface_async(dev->intf);
1451 		netif_dbg(dev, tx_err, dev->net,
1452 			  "tx: submit urb err %d\n", retval);
1453 		break;
1454 	case 0:
1455 		netif_trans_update(net);
1456 		__usbnet_queue_skb(&dev->txq, skb, tx_start);
1457 		if (dev->txq.qlen >= TX_QLEN (dev))
1458 			netif_stop_queue (net);
1459 	}
1460 	spin_unlock_irqrestore (&dev->txq.lock, flags);
1461 
1462 	if (retval) {
1463 		netif_dbg(dev, tx_err, dev->net, "drop, code %d\n", retval);
1464 drop:
1465 		dev->net->stats.tx_dropped++;
1466 not_drop:
1467 		if (skb)
1468 			dev_kfree_skb_any (skb);
1469 		if (urb) {
1470 			kfree(urb->sg);
1471 			usb_free_urb(urb);
1472 		}
1473 	} else
1474 		netif_dbg(dev, tx_queued, dev->net,
1475 			  "> tx, len %u, type 0x%x\n", length, skb->protocol);
1476 #ifdef CONFIG_PM
1477 deferred:
1478 #endif
1479 	return NETDEV_TX_OK;
1480 }
1481 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
1482 
1483 static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
1484 {
1485 	struct urb	*urb;
1486 	int		i;
1487 	int		ret = 0;
1488 
1489 	/* don't refill the queue all at once */
1490 	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
1491 		urb = usb_alloc_urb(0, flags);
1492 		if (urb != NULL) {
1493 			ret = rx_submit(dev, urb, flags);
1494 			if (ret)
1495 				goto err;
1496 		} else {
1497 			ret = -ENOMEM;
1498 			goto err;
1499 		}
1500 	}
1501 err:
1502 	return ret;
1503 }
1504 
1505 /*-------------------------------------------------------------------------*/
1506 
1507 // tasklet (work deferred from completions, in_irq) or timer
1508 
1509 static void usbnet_bh (struct timer_list *t)
1510 {
1511 	struct usbnet		*dev = from_timer(dev, t, delay);
1512 	struct sk_buff		*skb;
1513 	struct skb_data		*entry;
1514 
1515 	while ((skb = skb_dequeue (&dev->done))) {
1516 		entry = (struct skb_data *) skb->cb;
1517 		switch (entry->state) {
1518 		case rx_done:
1519 			entry->state = rx_cleanup;
1520 			rx_process (dev, skb);
1521 			continue;
1522 		case tx_done:
1523 			kfree(entry->urb->sg);
1524 			/* fall through */
1525 		case rx_cleanup:
1526 			usb_free_urb (entry->urb);
1527 			dev_kfree_skb (skb);
1528 			continue;
1529 		default:
1530 			netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
1531 		}
1532 	}
1533 
1534 	/* restart RX again after disabling due to high error rate */
1535 	clear_bit(EVENT_RX_KILL, &dev->flags);
1536 
1537 	/* waiting for all pending urbs to complete?
1538 	 * only then can we forgo submitting anew
1539 	 */
1540 	if (waitqueue_active(&dev->wait)) {
1541 		if (dev->txq.qlen + dev->rxq.qlen + dev->done.qlen == 0)
1542 			wake_up_all(&dev->wait);
1543 
1544 	// or are we maybe short a few urbs?
1545 	} else if (netif_running (dev->net) &&
1546 		   netif_device_present (dev->net) &&
1547 		   netif_carrier_ok(dev->net) &&
1548 		   !timer_pending(&dev->delay) &&
1549 		   !test_bit(EVENT_RX_PAUSED, &dev->flags) &&
1550 		   !test_bit(EVENT_RX_HALT, &dev->flags)) {
1551 		int	temp = dev->rxq.qlen;
1552 
1553 		if (temp < RX_QLEN(dev)) {
1554 			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
1555 				return;
1556 			if (temp != dev->rxq.qlen)
1557 				netif_dbg(dev, link, dev->net,
1558 					  "rxqlen %d --> %d\n",
1559 					  temp, dev->rxq.qlen);
1560 			if (dev->rxq.qlen < RX_QLEN(dev))
1561 				tasklet_schedule (&dev->bh);
1562 		}
1563 		if (dev->txq.qlen < TX_QLEN (dev))
1564 			netif_wake_queue (dev->net);
1565 	}
1566 }
1567 
1568 
1569 /*-------------------------------------------------------------------------
1570  *
1571  * USB Device Driver support
1572  *
1573  *-------------------------------------------------------------------------*/
1574 
1575 // precondition: never called in_interrupt
1576 
1577 void usbnet_disconnect (struct usb_interface *intf)
1578 {
1579 	struct usbnet		*dev;
1580 	struct usb_device	*xdev;
1581 	struct net_device	*net;
1582 
1583 	dev = usb_get_intfdata(intf);
1584 	usb_set_intfdata(intf, NULL);
1585 	if (!dev)
1586 		return;
1587 
1588 	xdev = interface_to_usbdev (intf);
1589 
1590 	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s\n",
1591 		   intf->dev.driver->name,
1592 		   xdev->bus->bus_name, xdev->devpath,
1593 		   dev->driver_info->description);
1594 
1595 	net = dev->net;
1596 	unregister_netdev (net);
1597 
1598 	cancel_work_sync(&dev->kevent);
1599 
1600 	usb_scuttle_anchored_urbs(&dev->deferred);
1601 
1602 	if (dev->driver_info->unbind)
1603 		dev->driver_info->unbind (dev, intf);
1604 
1605 	usb_kill_urb(dev->interrupt);
1606 	usb_free_urb(dev->interrupt);
1607 	kfree(dev->padding_pkt);
1608 
1609 	free_percpu(dev->stats64);
1610 	free_netdev(net);
1611 }
1612 EXPORT_SYMBOL_GPL(usbnet_disconnect);
1613 
1614 static const struct net_device_ops usbnet_netdev_ops = {
1615 	.ndo_open		= usbnet_open,
1616 	.ndo_stop		= usbnet_stop,
1617 	.ndo_start_xmit		= usbnet_start_xmit,
1618 	.ndo_tx_timeout		= usbnet_tx_timeout,
1619 	.ndo_set_rx_mode	= usbnet_set_rx_mode,
1620 	.ndo_change_mtu		= usbnet_change_mtu,
1621 	.ndo_get_stats64	= usbnet_get_stats64,
1622 	.ndo_set_mac_address 	= eth_mac_addr,
1623 	.ndo_validate_addr	= eth_validate_addr,
1624 };
1625 
1626 /*-------------------------------------------------------------------------*/
1627 
1628 // precondition: never called in_interrupt
1629 
1630 static struct device_type wlan_type = {
1631 	.name	= "wlan",
1632 };
1633 
1634 static struct device_type wwan_type = {
1635 	.name	= "wwan",
1636 };
1637 
1638 int
1639 usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
1640 {
1641 	struct usbnet			*dev;
1642 	struct net_device		*net;
1643 	struct usb_host_interface	*interface;
1644 	const struct driver_info	*info;
1645 	struct usb_device		*xdev;
1646 	int				status;
1647 	const char			*name;
1648 	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
1649 
1650 	/* usbnet already took usb runtime pm, so have to enable the feature
1651 	 * for usb interface, otherwise usb_autopm_get_interface may return
1652 	 * failure if RUNTIME_PM is enabled.
1653 	 */
1654 	if (!driver->supports_autosuspend) {
1655 		driver->supports_autosuspend = 1;
1656 		pm_runtime_enable(&udev->dev);
1657 	}
1658 
1659 	name = udev->dev.driver->name;
1660 	info = (const struct driver_info *) prod->driver_info;
1661 	if (!info) {
1662 		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
1663 		return -ENODEV;
1664 	}
1665 	xdev = interface_to_usbdev (udev);
1666 	interface = udev->cur_altsetting;
1667 
1668 	status = -ENOMEM;
1669 
1670 	// set up our own records
1671 	net = alloc_etherdev(sizeof(*dev));
1672 	if (!net)
1673 		goto out;
1674 
1675 	/* netdev_printk() needs this so do it as early as possible */
1676 	SET_NETDEV_DEV(net, &udev->dev);
1677 
1678 	dev = netdev_priv(net);
1679 	dev->udev = xdev;
1680 	dev->intf = udev;
1681 	dev->driver_info = info;
1682 	dev->driver_name = name;
1683 
1684 	dev->stats64 = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
1685 	if (!dev->stats64)
1686 		goto out0;
1687 
1688 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
1689 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
1690 	init_waitqueue_head(&dev->wait);
1691 	skb_queue_head_init (&dev->rxq);
1692 	skb_queue_head_init (&dev->txq);
1693 	skb_queue_head_init (&dev->done);
1694 	skb_queue_head_init(&dev->rxq_pause);
1695 	dev->bh.func = (void (*)(unsigned long))usbnet_bh;
1696 	dev->bh.data = (unsigned long)&dev->delay;
1697 	INIT_WORK (&dev->kevent, usbnet_deferred_kevent);
1698 	init_usb_anchor(&dev->deferred);
1699 	timer_setup(&dev->delay, usbnet_bh, 0);
1700 	mutex_init (&dev->phy_mutex);
1701 	mutex_init(&dev->interrupt_mutex);
1702 	dev->interrupt_count = 0;
1703 
1704 	dev->net = net;
1705 	strcpy (net->name, "usb%d");
1706 	memcpy (net->dev_addr, node_id, sizeof node_id);
1707 
1708 	/* rx and tx sides can use different message sizes;
1709 	 * bind() should set rx_urb_size in that case.
1710 	 */
1711 	dev->hard_mtu = net->mtu + net->hard_header_len;
1712 	net->min_mtu = 0;
1713 	net->max_mtu = ETH_MAX_MTU;
1714 
1715 	net->netdev_ops = &usbnet_netdev_ops;
1716 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
1717 	net->ethtool_ops = &usbnet_ethtool_ops;
1718 
1719 	// allow device-specific bind/init procedures
1720 	// NOTE net->name still not usable ...
1721 	if (info->bind) {
1722 		status = info->bind (dev, udev);
1723 		if (status < 0)
1724 			goto out1;
1725 
1726 		// heuristic:  "usb%d" for links we know are two-host,
1727 		// else "eth%d" when there's reasonable doubt.  userspace
1728 		// can rename the link if it knows better.
1729 		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
1730 		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
1731 		     (net->dev_addr [0] & 0x02) == 0))
1732 			strcpy (net->name, "eth%d");
1733 		/* WLAN devices should always be named "wlan%d" */
1734 		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1735 			strcpy(net->name, "wlan%d");
1736 		/* WWAN devices should always be named "wwan%d" */
1737 		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1738 			strcpy(net->name, "wwan%d");
1739 
1740 		/* devices that cannot do ARP */
1741 		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
1742 			net->flags |= IFF_NOARP;
1743 
1744 		/* maybe the remote can't receive an Ethernet MTU */
1745 		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
1746 			net->mtu = dev->hard_mtu - net->hard_header_len;
1747 	} else if (!info->in || !info->out)
1748 		status = usbnet_get_endpoints (dev, udev);
1749 	else {
1750 		dev->in = usb_rcvbulkpipe (xdev, info->in);
1751 		dev->out = usb_sndbulkpipe (xdev, info->out);
1752 		if (!(info->flags & FLAG_NO_SETINT))
1753 			status = usb_set_interface (xdev,
1754 				interface->desc.bInterfaceNumber,
1755 				interface->desc.bAlternateSetting);
1756 		else
1757 			status = 0;
1758 
1759 	}
1760 	if (status >= 0 && dev->status)
1761 		status = init_status (dev, udev);
1762 	if (status < 0)
1763 		goto out3;
1764 
1765 	if (!dev->rx_urb_size)
1766 		dev->rx_urb_size = dev->hard_mtu;
1767 	dev->maxpacket = usb_maxpacket (dev->udev, dev->out, 1);
1768 
1769 	/* let userspace know we have a random address */
1770 	if (ether_addr_equal(net->dev_addr, node_id))
1771 		net->addr_assign_type = NET_ADDR_RANDOM;
1772 
1773 	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1774 		SET_NETDEV_DEVTYPE(net, &wlan_type);
1775 	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1776 		SET_NETDEV_DEVTYPE(net, &wwan_type);
1777 
1778 	/* initialize max rx_qlen and tx_qlen */
1779 	usbnet_update_max_qlen(dev);
1780 
1781 	if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
1782 		!(info->flags & FLAG_MULTI_PACKET)) {
1783 		dev->padding_pkt = kzalloc(1, GFP_KERNEL);
1784 		if (!dev->padding_pkt) {
1785 			status = -ENOMEM;
1786 			goto out4;
1787 		}
1788 	}
1789 
1790 	status = register_netdev (net);
1791 	if (status)
1792 		goto out5;
1793 	netif_info(dev, probe, dev->net,
1794 		   "register '%s' at usb-%s-%s, %s, %pM\n",
1795 		   udev->dev.driver->name,
1796 		   xdev->bus->bus_name, xdev->devpath,
1797 		   dev->driver_info->description,
1798 		   net->dev_addr);
1799 
1800 	// ok, it's ready to go.
1801 	usb_set_intfdata (udev, dev);
1802 
1803 	netif_device_attach (net);
1804 
1805 	if (dev->driver_info->flags & FLAG_LINK_INTR)
1806 		usbnet_link_change(dev, 0, 0);
1807 
1808 	return 0;
1809 
1810 out5:
1811 	kfree(dev->padding_pkt);
1812 out4:
1813 	usb_free_urb(dev->interrupt);
1814 out3:
1815 	if (info->unbind)
1816 		info->unbind (dev, udev);
1817 out1:
1818 	/* subdrivers must undo all they did in bind() if they
1819 	 * fail it, but we may fail later and a deferred kevent
1820 	 * may trigger an error resubmitting itself and, worse,
1821 	 * schedule a timer. So we kill it all just in case.
1822 	 */
1823 	cancel_work_sync(&dev->kevent);
1824 	del_timer_sync(&dev->delay);
1825 	free_percpu(dev->stats64);
1826 out0:
1827 	free_netdev(net);
1828 out:
1829 	return status;
1830 }
1831 EXPORT_SYMBOL_GPL(usbnet_probe);
1832 
1833 /*-------------------------------------------------------------------------*/
1834 
1835 /*
1836  * suspend the whole driver as soon as the first interface is suspended
1837  * resume only when the last interface is resumed
1838  */
1839 
1840 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
1841 {
1842 	struct usbnet		*dev = usb_get_intfdata(intf);
1843 
1844 	if (!dev->suspend_count++) {
1845 		spin_lock_irq(&dev->txq.lock);
1846 		/* don't autosuspend while transmitting */
1847 		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
1848 			dev->suspend_count--;
1849 			spin_unlock_irq(&dev->txq.lock);
1850 			return -EBUSY;
1851 		} else {
1852 			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
1853 			spin_unlock_irq(&dev->txq.lock);
1854 		}
1855 		/*
1856 		 * accelerate emptying of the rx and queues, to avoid
1857 		 * having everything error out.
1858 		 */
1859 		netif_device_detach (dev->net);
1860 		usbnet_terminate_urbs(dev);
1861 		__usbnet_status_stop_force(dev);
1862 
1863 		/*
1864 		 * reattach so runtime management can use and
1865 		 * wake the device
1866 		 */
1867 		netif_device_attach (dev->net);
1868 	}
1869 	return 0;
1870 }
1871 EXPORT_SYMBOL_GPL(usbnet_suspend);
1872 
1873 int usbnet_resume (struct usb_interface *intf)
1874 {
1875 	struct usbnet		*dev = usb_get_intfdata(intf);
1876 	struct sk_buff          *skb;
1877 	struct urb              *res;
1878 	int                     retval;
1879 
1880 	if (!--dev->suspend_count) {
1881 		/* resume interrupt URB if it was previously submitted */
1882 		__usbnet_status_start_force(dev, GFP_NOIO);
1883 
1884 		spin_lock_irq(&dev->txq.lock);
1885 		while ((res = usb_get_from_anchor(&dev->deferred))) {
1886 
1887 			skb = (struct sk_buff *)res->context;
1888 			retval = usb_submit_urb(res, GFP_ATOMIC);
1889 			if (retval < 0) {
1890 				dev_kfree_skb_any(skb);
1891 				kfree(res->sg);
1892 				usb_free_urb(res);
1893 				usb_autopm_put_interface_async(dev->intf);
1894 			} else {
1895 				netif_trans_update(dev->net);
1896 				__skb_queue_tail(&dev->txq, skb);
1897 			}
1898 		}
1899 
1900 		smp_mb();
1901 		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
1902 		spin_unlock_irq(&dev->txq.lock);
1903 
1904 		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
1905 			/* handle remote wakeup ASAP
1906 			 * we cannot race against stop
1907 			 */
1908 			if (netif_device_present(dev->net) &&
1909 				!timer_pending(&dev->delay) &&
1910 				!test_bit(EVENT_RX_HALT, &dev->flags))
1911 					rx_alloc_submit(dev, GFP_NOIO);
1912 
1913 			if (!(dev->txq.qlen >= TX_QLEN(dev)))
1914 				netif_tx_wake_all_queues(dev->net);
1915 			tasklet_schedule (&dev->bh);
1916 		}
1917 	}
1918 
1919 	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
1920 		usb_autopm_get_interface_no_resume(intf);
1921 
1922 	return 0;
1923 }
1924 EXPORT_SYMBOL_GPL(usbnet_resume);
1925 
1926 /*
1927  * Either a subdriver implements manage_power, then it is assumed to always
1928  * be ready to be suspended or it reports the readiness to be suspended
1929  * explicitly
1930  */
1931 void usbnet_device_suggests_idle(struct usbnet *dev)
1932 {
1933 	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
1934 		dev->intf->needs_remote_wakeup = 1;
1935 		usb_autopm_put_interface_async(dev->intf);
1936 	}
1937 }
1938 EXPORT_SYMBOL(usbnet_device_suggests_idle);
1939 
1940 /*
1941  * For devices that can do without special commands
1942  */
1943 int usbnet_manage_power(struct usbnet *dev, int on)
1944 {
1945 	dev->intf->needs_remote_wakeup = on;
1946 	return 0;
1947 }
1948 EXPORT_SYMBOL(usbnet_manage_power);
1949 
1950 void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
1951 {
1952 	/* update link after link is reseted */
1953 	if (link && !need_reset)
1954 		netif_carrier_on(dev->net);
1955 	else
1956 		netif_carrier_off(dev->net);
1957 
1958 	if (need_reset && link)
1959 		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
1960 	else
1961 		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
1962 }
1963 EXPORT_SYMBOL(usbnet_link_change);
1964 
1965 /*-------------------------------------------------------------------------*/
1966 static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1967 			     u16 value, u16 index, void *data, u16 size)
1968 {
1969 	void *buf = NULL;
1970 	int err = -ENOMEM;
1971 
1972 	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
1973 		   " value=0x%04x index=0x%04x size=%d\n",
1974 		   cmd, reqtype, value, index, size);
1975 
1976 	if (size) {
1977 		buf = kmalloc(size, GFP_KERNEL);
1978 		if (!buf)
1979 			goto out;
1980 	}
1981 
1982 	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
1983 			      cmd, reqtype, value, index, buf, size,
1984 			      USB_CTRL_GET_TIMEOUT);
1985 	if (err > 0 && err <= size) {
1986         if (data)
1987             memcpy(data, buf, err);
1988         else
1989             netdev_dbg(dev->net,
1990                 "Huh? Data requested but thrown away.\n");
1991     }
1992 	kfree(buf);
1993 out:
1994 	return err;
1995 }
1996 
1997 static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1998 			      u16 value, u16 index, const void *data,
1999 			      u16 size)
2000 {
2001 	void *buf = NULL;
2002 	int err = -ENOMEM;
2003 
2004 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
2005 		   " value=0x%04x index=0x%04x size=%d\n",
2006 		   cmd, reqtype, value, index, size);
2007 
2008 	if (data) {
2009 		buf = kmemdup(data, size, GFP_KERNEL);
2010 		if (!buf)
2011 			goto out;
2012 	} else {
2013         if (size) {
2014             WARN_ON_ONCE(1);
2015             err = -EINVAL;
2016             goto out;
2017         }
2018     }
2019 
2020 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
2021 			      cmd, reqtype, value, index, buf, size,
2022 			      USB_CTRL_SET_TIMEOUT);
2023 	kfree(buf);
2024 
2025 out:
2026 	return err;
2027 }
2028 
2029 /*
2030  * The function can't be called inside suspend/resume callback,
2031  * otherwise deadlock will be caused.
2032  */
2033 int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
2034 		    u16 value, u16 index, void *data, u16 size)
2035 {
2036 	int ret;
2037 
2038 	if (usb_autopm_get_interface(dev->intf) < 0)
2039 		return -ENODEV;
2040 	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
2041 				data, size);
2042 	usb_autopm_put_interface(dev->intf);
2043 	return ret;
2044 }
2045 EXPORT_SYMBOL_GPL(usbnet_read_cmd);
2046 
2047 /*
2048  * The function can't be called inside suspend/resume callback,
2049  * otherwise deadlock will be caused.
2050  */
2051 int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
2052 		     u16 value, u16 index, const void *data, u16 size)
2053 {
2054 	int ret;
2055 
2056 	if (usb_autopm_get_interface(dev->intf) < 0)
2057 		return -ENODEV;
2058 	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
2059 				 data, size);
2060 	usb_autopm_put_interface(dev->intf);
2061 	return ret;
2062 }
2063 EXPORT_SYMBOL_GPL(usbnet_write_cmd);
2064 
2065 /*
2066  * The function can be called inside suspend/resume callback safely
2067  * and should only be called by suspend/resume callback generally.
2068  */
2069 int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
2070 			  u16 value, u16 index, void *data, u16 size)
2071 {
2072 	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
2073 				 data, size);
2074 }
2075 EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
2076 
2077 /*
2078  * The function can be called inside suspend/resume callback safely
2079  * and should only be called by suspend/resume callback generally.
2080  */
2081 int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
2082 			  u16 value, u16 index, const void *data,
2083 			  u16 size)
2084 {
2085 	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
2086 				  data, size);
2087 }
2088 EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
2089 
2090 static void usbnet_async_cmd_cb(struct urb *urb)
2091 {
2092 	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
2093 	int status = urb->status;
2094 
2095 	if (status < 0)
2096 		dev_dbg(&urb->dev->dev, "%s failed with %d",
2097 			__func__, status);
2098 
2099 	kfree(req);
2100 	usb_free_urb(urb);
2101 }
2102 
2103 /*
2104  * The caller must make sure that device can't be put into suspend
2105  * state until the control URB completes.
2106  */
2107 int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
2108 			   u16 value, u16 index, const void *data, u16 size)
2109 {
2110 	struct usb_ctrlrequest *req = NULL;
2111 	struct urb *urb;
2112 	int err = -ENOMEM;
2113 	void *buf = NULL;
2114 
2115 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
2116 		   " value=0x%04x index=0x%04x size=%d\n",
2117 		   cmd, reqtype, value, index, size);
2118 
2119 	urb = usb_alloc_urb(0, GFP_ATOMIC);
2120 	if (!urb)
2121 		goto fail;
2122 
2123 	if (data) {
2124 		buf = kmemdup(data, size, GFP_ATOMIC);
2125 		if (!buf) {
2126 			netdev_err(dev->net, "Error allocating buffer"
2127 				   " in %s!\n", __func__);
2128 			goto fail_free;
2129 		}
2130 	}
2131 
2132 	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
2133 	if (!req)
2134 		goto fail_free_buf;
2135 
2136 	req->bRequestType = reqtype;
2137 	req->bRequest = cmd;
2138 	req->wValue = cpu_to_le16(value);
2139 	req->wIndex = cpu_to_le16(index);
2140 	req->wLength = cpu_to_le16(size);
2141 
2142 	usb_fill_control_urb(urb, dev->udev,
2143 			     usb_sndctrlpipe(dev->udev, 0),
2144 			     (void *)req, buf, size,
2145 			     usbnet_async_cmd_cb, req);
2146 	urb->transfer_flags |= URB_FREE_BUFFER;
2147 
2148 	err = usb_submit_urb(urb, GFP_ATOMIC);
2149 	if (err < 0) {
2150 		netdev_err(dev->net, "Error submitting the control"
2151 			   " message: status=%d\n", err);
2152 		goto fail_free;
2153 	}
2154 	return 0;
2155 
2156 fail_free_buf:
2157 	kfree(buf);
2158 fail_free:
2159 	kfree(req);
2160 	usb_free_urb(urb);
2161 fail:
2162 	return err;
2163 
2164 }
2165 EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
2166 /*-------------------------------------------------------------------------*/
2167 
2168 static int __init usbnet_init(void)
2169 {
2170 	/* Compiler should optimize this out. */
2171 	BUILD_BUG_ON(
2172 		FIELD_SIZEOF(struct sk_buff, cb) < sizeof(struct skb_data));
2173 
2174 	eth_random_addr(node_id);
2175 	return 0;
2176 }
2177 module_init(usbnet_init);
2178 
2179 static void __exit usbnet_exit(void)
2180 {
2181 }
2182 module_exit(usbnet_exit);
2183 
2184 MODULE_AUTHOR("David Brownell");
2185 MODULE_DESCRIPTION("USB network driver framework");
2186 MODULE_LICENSE("GPL");
2187