xref: /openbmc/linux/drivers/net/usb/usbnet.c (revision e5242c5f)
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 #include <linux/module.h>
21 #include <linux/init.h>
22 #include <linux/netdevice.h>
23 #include <linux/etherdevice.h>
24 #include <linux/ctype.h>
25 #include <linux/ethtool.h>
26 #include <linux/workqueue.h>
27 #include <linux/mii.h>
28 #include <linux/usb.h>
29 #include <linux/usb/usbnet.h>
30 #include <linux/slab.h>
31 #include <linux/kernel.h>
32 #include <linux/pm_runtime.h>
33 
34 /*-------------------------------------------------------------------------*/
35 
36 /*
37  * Nineteen USB 1.1 max size bulk transactions per frame (ms), max.
38  * Several dozen bytes of IPv4 data can fit in two such transactions.
39  * One maximum size Ethernet packet takes twenty four of them.
40  * For high speed, each frame comfortably fits almost 36 max size
41  * Ethernet packets (so queues should be bigger).
42  *
43  * The goal is to let the USB host controller be busy for 5msec or
44  * more before an irq is required, under load.  Jumbograms change
45  * the equation.
46  */
47 #define	MAX_QUEUE_MEMORY	(60 * 1518)
48 #define	RX_QLEN(dev)		((dev)->rx_qlen)
49 #define	TX_QLEN(dev)		((dev)->tx_qlen)
50 
51 // reawaken network queue this soon after stopping; else watchdog barks
52 #define TX_TIMEOUT_JIFFIES	(5*HZ)
53 
54 /* throttle rx/tx briefly after some faults, so hub_wq might disconnect()
55  * us (it polls at HZ/4 usually) before we report too many false errors.
56  */
57 #define THROTTLE_JIFFIES	(HZ/8)
58 
59 // between wakeups
60 #define UNLINK_TIMEOUT_MS	3
61 
62 /*-------------------------------------------------------------------------*/
63 
64 /* use ethtool to change the level for any given device */
65 static int msg_level = -1;
66 module_param (msg_level, int, 0);
67 MODULE_PARM_DESC (msg_level, "Override default message level");
68 
69 /*-------------------------------------------------------------------------*/
70 
71 static const char * const usbnet_event_names[] = {
72 	[EVENT_TX_HALT]		   = "EVENT_TX_HALT",
73 	[EVENT_RX_HALT]		   = "EVENT_RX_HALT",
74 	[EVENT_RX_MEMORY]	   = "EVENT_RX_MEMORY",
75 	[EVENT_STS_SPLIT]	   = "EVENT_STS_SPLIT",
76 	[EVENT_LINK_RESET]	   = "EVENT_LINK_RESET",
77 	[EVENT_RX_PAUSED]	   = "EVENT_RX_PAUSED",
78 	[EVENT_DEV_ASLEEP]	   = "EVENT_DEV_ASLEEP",
79 	[EVENT_DEV_OPEN]	   = "EVENT_DEV_OPEN",
80 	[EVENT_DEVICE_REPORT_IDLE] = "EVENT_DEVICE_REPORT_IDLE",
81 	[EVENT_NO_RUNTIME_PM]	   = "EVENT_NO_RUNTIME_PM",
82 	[EVENT_RX_KILL]		   = "EVENT_RX_KILL",
83 	[EVENT_LINK_CHANGE]	   = "EVENT_LINK_CHANGE",
84 	[EVENT_SET_RX_MODE]	   = "EVENT_SET_RX_MODE",
85 	[EVENT_NO_IP_ALIGN]	   = "EVENT_NO_IP_ALIGN",
86 };
87 
88 /* handles CDC Ethernet and many other network "bulk data" interfaces */
89 int usbnet_get_endpoints(struct usbnet *dev, struct usb_interface *intf)
90 {
91 	int				tmp;
92 	struct usb_host_interface	*alt = NULL;
93 	struct usb_host_endpoint	*in = NULL, *out = NULL;
94 	struct usb_host_endpoint	*status = NULL;
95 
96 	for (tmp = 0; tmp < intf->num_altsetting; tmp++) {
97 		unsigned	ep;
98 
99 		in = out = status = NULL;
100 		alt = intf->altsetting + tmp;
101 
102 		/* take the first altsetting with in-bulk + out-bulk;
103 		 * remember any status endpoint, just in case;
104 		 * ignore other endpoints and altsettings.
105 		 */
106 		for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
107 			struct usb_host_endpoint	*e;
108 			int				intr = 0;
109 
110 			e = alt->endpoint + ep;
111 
112 			/* ignore endpoints which cannot transfer data */
113 			if (!usb_endpoint_maxp(&e->desc))
114 				continue;
115 
116 			switch (e->desc.bmAttributes) {
117 			case USB_ENDPOINT_XFER_INT:
118 				if (!usb_endpoint_dir_in(&e->desc))
119 					continue;
120 				intr = 1;
121 				fallthrough;
122 			case USB_ENDPOINT_XFER_BULK:
123 				break;
124 			default:
125 				continue;
126 			}
127 			if (usb_endpoint_dir_in(&e->desc)) {
128 				if (!intr && !in)
129 					in = e;
130 				else if (intr && !status)
131 					status = e;
132 			} else {
133 				if (!out)
134 					out = e;
135 			}
136 		}
137 		if (in && out)
138 			break;
139 	}
140 	if (!alt || !in || !out)
141 		return -EINVAL;
142 
143 	if (alt->desc.bAlternateSetting != 0 ||
144 	    !(dev->driver_info->flags & FLAG_NO_SETINT)) {
145 		tmp = usb_set_interface (dev->udev, alt->desc.bInterfaceNumber,
146 				alt->desc.bAlternateSetting);
147 		if (tmp < 0)
148 			return tmp;
149 	}
150 
151 	dev->in = usb_rcvbulkpipe (dev->udev,
152 			in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
153 	dev->out = usb_sndbulkpipe (dev->udev,
154 			out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
155 	dev->status = status;
156 	return 0;
157 }
158 EXPORT_SYMBOL_GPL(usbnet_get_endpoints);
159 
160 int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
161 {
162 	u8		addr[ETH_ALEN];
163 	int 		tmp = -1, ret;
164 	unsigned char	buf [13];
165 
166 	ret = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
167 	if (ret == 12)
168 		tmp = hex2bin(addr, buf, 6);
169 	if (tmp < 0) {
170 		dev_dbg(&dev->udev->dev,
171 			"bad MAC string %d fetch, %d\n", iMACAddress, tmp);
172 		if (ret >= 0)
173 			ret = -EINVAL;
174 		return ret;
175 	}
176 	eth_hw_addr_set(dev->net, addr);
177 	return 0;
178 }
179 EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
180 
181 static void intr_complete (struct urb *urb)
182 {
183 	struct usbnet	*dev = urb->context;
184 	int		status = urb->status;
185 
186 	switch (status) {
187 	/* success */
188 	case 0:
189 		dev->driver_info->status(dev, urb);
190 		break;
191 
192 	/* software-driven interface shutdown */
193 	case -ENOENT:		/* urb killed */
194 	case -ESHUTDOWN:	/* hardware gone */
195 		netif_dbg(dev, ifdown, dev->net,
196 			  "intr shutdown, code %d\n", status);
197 		return;
198 
199 	/* NOTE:  not throttling like RX/TX, since this endpoint
200 	 * already polls infrequently
201 	 */
202 	default:
203 		netdev_dbg(dev->net, "intr status %d\n", status);
204 		break;
205 	}
206 
207 	status = usb_submit_urb (urb, GFP_ATOMIC);
208 	if (status != 0)
209 		netif_err(dev, timer, dev->net,
210 			  "intr resubmit --> %d\n", status);
211 }
212 
213 static int init_status (struct usbnet *dev, struct usb_interface *intf)
214 {
215 	char		*buf = NULL;
216 	unsigned	pipe = 0;
217 	unsigned	maxp;
218 	unsigned	period;
219 
220 	if (!dev->driver_info->status)
221 		return 0;
222 
223 	pipe = usb_rcvintpipe (dev->udev,
224 			dev->status->desc.bEndpointAddress
225 				& USB_ENDPOINT_NUMBER_MASK);
226 	maxp = usb_maxpacket(dev->udev, pipe);
227 
228 	/* avoid 1 msec chatter:  min 8 msec poll rate */
229 	period = max ((int) dev->status->desc.bInterval,
230 		(dev->udev->speed == USB_SPEED_HIGH) ? 7 : 3);
231 
232 	buf = kmalloc (maxp, GFP_KERNEL);
233 	if (buf) {
234 		dev->interrupt = usb_alloc_urb (0, GFP_KERNEL);
235 		if (!dev->interrupt) {
236 			kfree (buf);
237 			return -ENOMEM;
238 		} else {
239 			usb_fill_int_urb(dev->interrupt, dev->udev, pipe,
240 				buf, maxp, intr_complete, dev, period);
241 			dev->interrupt->transfer_flags |= URB_FREE_BUFFER;
242 			dev_dbg(&intf->dev,
243 				"status ep%din, %d bytes period %d\n",
244 				usb_pipeendpoint(pipe), maxp, period);
245 		}
246 	}
247 	return 0;
248 }
249 
250 /* Submit the interrupt URB if not previously submitted, increasing refcount */
251 int usbnet_status_start(struct usbnet *dev, gfp_t mem_flags)
252 {
253 	int ret = 0;
254 
255 	WARN_ON_ONCE(dev->interrupt == NULL);
256 	if (dev->interrupt) {
257 		mutex_lock(&dev->interrupt_mutex);
258 
259 		if (++dev->interrupt_count == 1)
260 			ret = usb_submit_urb(dev->interrupt, mem_flags);
261 
262 		dev_dbg(&dev->udev->dev, "incremented interrupt URB count to %d\n",
263 			dev->interrupt_count);
264 		mutex_unlock(&dev->interrupt_mutex);
265 	}
266 	return ret;
267 }
268 EXPORT_SYMBOL_GPL(usbnet_status_start);
269 
270 /* For resume; submit interrupt URB if previously submitted */
271 static int __usbnet_status_start_force(struct usbnet *dev, gfp_t mem_flags)
272 {
273 	int ret = 0;
274 
275 	mutex_lock(&dev->interrupt_mutex);
276 	if (dev->interrupt_count) {
277 		ret = usb_submit_urb(dev->interrupt, mem_flags);
278 		dev_dbg(&dev->udev->dev,
279 			"submitted interrupt URB for resume\n");
280 	}
281 	mutex_unlock(&dev->interrupt_mutex);
282 	return ret;
283 }
284 
285 /* Kill the interrupt URB if all submitters want it killed */
286 void usbnet_status_stop(struct usbnet *dev)
287 {
288 	if (dev->interrupt) {
289 		mutex_lock(&dev->interrupt_mutex);
290 		WARN_ON(dev->interrupt_count == 0);
291 
292 		if (dev->interrupt_count && --dev->interrupt_count == 0)
293 			usb_kill_urb(dev->interrupt);
294 
295 		dev_dbg(&dev->udev->dev,
296 			"decremented interrupt URB count to %d\n",
297 			dev->interrupt_count);
298 		mutex_unlock(&dev->interrupt_mutex);
299 	}
300 }
301 EXPORT_SYMBOL_GPL(usbnet_status_stop);
302 
303 /* For suspend; always kill interrupt URB */
304 static void __usbnet_status_stop_force(struct usbnet *dev)
305 {
306 	if (dev->interrupt) {
307 		mutex_lock(&dev->interrupt_mutex);
308 		usb_kill_urb(dev->interrupt);
309 		dev_dbg(&dev->udev->dev, "killed interrupt URB for suspend\n");
310 		mutex_unlock(&dev->interrupt_mutex);
311 	}
312 }
313 
314 /* Passes this packet up the stack, updating its accounting.
315  * Some link protocols batch packets, so their rx_fixup paths
316  * can return clones as well as just modify the original skb.
317  */
318 void usbnet_skb_return (struct usbnet *dev, struct sk_buff *skb)
319 {
320 	struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->net->tstats);
321 	unsigned long flags;
322 	int	status;
323 
324 	if (test_bit(EVENT_RX_PAUSED, &dev->flags)) {
325 		skb_queue_tail(&dev->rxq_pause, skb);
326 		return;
327 	}
328 
329 	/* only update if unset to allow minidriver rx_fixup override */
330 	if (skb->protocol == 0)
331 		skb->protocol = eth_type_trans (skb, dev->net);
332 
333 	flags = u64_stats_update_begin_irqsave(&stats64->syncp);
334 	u64_stats_inc(&stats64->rx_packets);
335 	u64_stats_add(&stats64->rx_bytes, skb->len);
336 	u64_stats_update_end_irqrestore(&stats64->syncp, flags);
337 
338 	netif_dbg(dev, rx_status, dev->net, "< rx, len %zu, type 0x%x\n",
339 		  skb->len + sizeof (struct ethhdr), skb->protocol);
340 	memset (skb->cb, 0, sizeof (struct skb_data));
341 
342 	if (skb_defer_rx_timestamp(skb))
343 		return;
344 
345 	status = netif_rx (skb);
346 	if (status != NET_RX_SUCCESS)
347 		netif_dbg(dev, rx_err, dev->net,
348 			  "netif_rx status %d\n", status);
349 }
350 EXPORT_SYMBOL_GPL(usbnet_skb_return);
351 
352 /* must be called if hard_mtu or rx_urb_size changed */
353 void usbnet_update_max_qlen(struct usbnet *dev)
354 {
355 	enum usb_device_speed speed = dev->udev->speed;
356 
357 	if (!dev->rx_urb_size || !dev->hard_mtu)
358 		goto insanity;
359 	switch (speed) {
360 	case USB_SPEED_HIGH:
361 		dev->rx_qlen = MAX_QUEUE_MEMORY / dev->rx_urb_size;
362 		dev->tx_qlen = MAX_QUEUE_MEMORY / dev->hard_mtu;
363 		break;
364 	case USB_SPEED_SUPER:
365 	case USB_SPEED_SUPER_PLUS:
366 		/*
367 		 * Not take default 5ms qlen for super speed HC to
368 		 * save memory, and iperf tests show 2.5ms qlen can
369 		 * work well
370 		 */
371 		dev->rx_qlen = 5 * MAX_QUEUE_MEMORY / dev->rx_urb_size;
372 		dev->tx_qlen = 5 * MAX_QUEUE_MEMORY / dev->hard_mtu;
373 		break;
374 	default:
375 insanity:
376 		dev->rx_qlen = dev->tx_qlen = 4;
377 	}
378 }
379 EXPORT_SYMBOL_GPL(usbnet_update_max_qlen);
380 
381 
382 /*-------------------------------------------------------------------------
383  *
384  * Network Device Driver (peer link to "Host Device", from USB host)
385  *
386  *-------------------------------------------------------------------------*/
387 
388 int usbnet_change_mtu (struct net_device *net, int new_mtu)
389 {
390 	struct usbnet	*dev = netdev_priv(net);
391 	int		ll_mtu = new_mtu + net->hard_header_len;
392 	int		old_hard_mtu = dev->hard_mtu;
393 	int		old_rx_urb_size = dev->rx_urb_size;
394 
395 	// no second zero-length packet read wanted after mtu-sized packets
396 	if ((ll_mtu % dev->maxpacket) == 0)
397 		return -EDOM;
398 	net->mtu = new_mtu;
399 
400 	dev->hard_mtu = net->mtu + net->hard_header_len;
401 	if (dev->rx_urb_size == old_hard_mtu) {
402 		dev->rx_urb_size = dev->hard_mtu;
403 		if (dev->rx_urb_size > old_rx_urb_size) {
404 			usbnet_pause_rx(dev);
405 			usbnet_unlink_rx_urbs(dev);
406 			usbnet_resume_rx(dev);
407 		}
408 	}
409 
410 	/* max qlen depend on hard_mtu and rx_urb_size */
411 	usbnet_update_max_qlen(dev);
412 
413 	return 0;
414 }
415 EXPORT_SYMBOL_GPL(usbnet_change_mtu);
416 
417 /* The caller must hold list->lock */
418 static void __usbnet_queue_skb(struct sk_buff_head *list,
419 			struct sk_buff *newsk, enum skb_state state)
420 {
421 	struct skb_data *entry = (struct skb_data *) newsk->cb;
422 
423 	__skb_queue_tail(list, newsk);
424 	entry->state = state;
425 }
426 
427 /*-------------------------------------------------------------------------*/
428 
429 /* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
430  * completion callbacks.  2.5 should have fixed those bugs...
431  */
432 
433 static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
434 		struct sk_buff_head *list, enum skb_state state)
435 {
436 	unsigned long		flags;
437 	enum skb_state 		old_state;
438 	struct skb_data *entry = (struct skb_data *) skb->cb;
439 
440 	spin_lock_irqsave(&list->lock, flags);
441 	old_state = entry->state;
442 	entry->state = state;
443 	__skb_unlink(skb, list);
444 
445 	/* defer_bh() is never called with list == &dev->done.
446 	 * spin_lock_nested() tells lockdep that it is OK to take
447 	 * dev->done.lock here with list->lock held.
448 	 */
449 	spin_lock_nested(&dev->done.lock, SINGLE_DEPTH_NESTING);
450 
451 	__skb_queue_tail(&dev->done, skb);
452 	if (dev->done.qlen == 1)
453 		tasklet_schedule(&dev->bh);
454 	spin_unlock(&dev->done.lock);
455 	spin_unlock_irqrestore(&list->lock, flags);
456 	return old_state;
457 }
458 
459 /* some work can't be done in tasklets, so we use keventd
460  *
461  * NOTE:  annoying asymmetry:  if it's active, schedule_work() fails,
462  * but tasklet_schedule() doesn't.  hope the failure is rare.
463  */
464 void usbnet_defer_kevent (struct usbnet *dev, int work)
465 {
466 	set_bit (work, &dev->flags);
467 	if (!usbnet_going_away(dev)) {
468 		if (!schedule_work(&dev->kevent))
469 			netdev_dbg(dev->net,
470 				   "kevent %s may have been dropped\n",
471 				   usbnet_event_names[work]);
472 		else
473 			netdev_dbg(dev->net,
474 				   "kevent %s scheduled\n", usbnet_event_names[work]);
475 	}
476 }
477 EXPORT_SYMBOL_GPL(usbnet_defer_kevent);
478 
479 /*-------------------------------------------------------------------------*/
480 
481 static void rx_complete (struct urb *urb);
482 
483 static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
484 {
485 	struct sk_buff		*skb;
486 	struct skb_data		*entry;
487 	int			retval = 0;
488 	unsigned long		lockflags;
489 	size_t			size = dev->rx_urb_size;
490 
491 	/* prevent rx skb allocation when error ratio is high */
492 	if (test_bit(EVENT_RX_KILL, &dev->flags)) {
493 		usb_free_urb(urb);
494 		return -ENOLINK;
495 	}
496 
497 	if (test_bit(EVENT_NO_IP_ALIGN, &dev->flags))
498 		skb = __netdev_alloc_skb(dev->net, size, flags);
499 	else
500 		skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
501 	if (!skb) {
502 		netif_dbg(dev, rx_err, dev->net, "no rx skb\n");
503 		usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
504 		usb_free_urb (urb);
505 		return -ENOMEM;
506 	}
507 
508 	entry = (struct skb_data *) skb->cb;
509 	entry->urb = urb;
510 	entry->dev = dev;
511 	entry->length = 0;
512 
513 	usb_fill_bulk_urb (urb, dev->udev, dev->in,
514 		skb->data, size, rx_complete, skb);
515 
516 	spin_lock_irqsave (&dev->rxq.lock, lockflags);
517 
518 	if (netif_running (dev->net) &&
519 	    netif_device_present (dev->net) &&
520 	    test_bit(EVENT_DEV_OPEN, &dev->flags) &&
521 	    !test_bit (EVENT_RX_HALT, &dev->flags) &&
522 	    !test_bit (EVENT_DEV_ASLEEP, &dev->flags)) {
523 		switch (retval = usb_submit_urb (urb, GFP_ATOMIC)) {
524 		case -EPIPE:
525 			usbnet_defer_kevent (dev, EVENT_RX_HALT);
526 			break;
527 		case -ENOMEM:
528 			usbnet_defer_kevent (dev, EVENT_RX_MEMORY);
529 			break;
530 		case -ENODEV:
531 			netif_dbg(dev, ifdown, dev->net, "device gone\n");
532 			netif_device_detach (dev->net);
533 			break;
534 		case -EHOSTUNREACH:
535 			retval = -ENOLINK;
536 			break;
537 		default:
538 			netif_dbg(dev, rx_err, dev->net,
539 				  "rx submit, %d\n", retval);
540 			tasklet_schedule (&dev->bh);
541 			break;
542 		case 0:
543 			if (!usbnet_going_away(dev))
544 				__usbnet_queue_skb(&dev->rxq, skb, rx_start);
545 		}
546 	} else {
547 		netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
548 		retval = -ENOLINK;
549 	}
550 	spin_unlock_irqrestore (&dev->rxq.lock, lockflags);
551 	if (retval) {
552 		dev_kfree_skb_any (skb);
553 		usb_free_urb (urb);
554 	}
555 	return retval;
556 }
557 
558 
559 /*-------------------------------------------------------------------------*/
560 
561 static inline int rx_process(struct usbnet *dev, struct sk_buff *skb)
562 {
563 	if (dev->driver_info->rx_fixup &&
564 	    !dev->driver_info->rx_fixup (dev, skb)) {
565 		/* With RX_ASSEMBLE, rx_fixup() must update counters */
566 		if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
567 			dev->net->stats.rx_errors++;
568 		return -EPROTO;
569 	}
570 	// else network stack removes extra byte if we forced a short packet
571 
572 	/* all data was already cloned from skb inside the driver */
573 	if (dev->driver_info->flags & FLAG_MULTI_PACKET)
574 		return -EALREADY;
575 
576 	if (skb->len < ETH_HLEN) {
577 		dev->net->stats.rx_errors++;
578 		dev->net->stats.rx_length_errors++;
579 		netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len);
580 		return -EPROTO;
581 	}
582 
583 	usbnet_skb_return(dev, skb);
584 	return 0;
585 }
586 
587 /*-------------------------------------------------------------------------*/
588 
589 static void rx_complete (struct urb *urb)
590 {
591 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
592 	struct skb_data		*entry = (struct skb_data *) skb->cb;
593 	struct usbnet		*dev = entry->dev;
594 	int			urb_status = urb->status;
595 	enum skb_state		state;
596 
597 	skb_put (skb, urb->actual_length);
598 	state = rx_done;
599 	entry->urb = NULL;
600 
601 	switch (urb_status) {
602 	/* success */
603 	case 0:
604 		break;
605 
606 	/* stalls need manual reset. this is rare ... except that
607 	 * when going through USB 2.0 TTs, unplug appears this way.
608 	 * we avoid the highspeed version of the ETIMEDOUT/EILSEQ
609 	 * storm, recovering as needed.
610 	 */
611 	case -EPIPE:
612 		dev->net->stats.rx_errors++;
613 		usbnet_defer_kevent (dev, EVENT_RX_HALT);
614 		fallthrough;
615 
616 	/* software-driven interface shutdown */
617 	case -ECONNRESET:		/* async unlink */
618 	case -ESHUTDOWN:		/* hardware gone */
619 		netif_dbg(dev, ifdown, dev->net,
620 			  "rx shutdown, code %d\n", urb_status);
621 		goto block;
622 
623 	/* we get controller i/o faults during hub_wq disconnect() delays.
624 	 * throttle down resubmits, to avoid log floods; just temporarily,
625 	 * so we still recover when the fault isn't a hub_wq delay.
626 	 */
627 	case -EPROTO:
628 	case -ETIME:
629 	case -EILSEQ:
630 		dev->net->stats.rx_errors++;
631 		if (!timer_pending (&dev->delay)) {
632 			mod_timer (&dev->delay, jiffies + THROTTLE_JIFFIES);
633 			netif_dbg(dev, link, dev->net,
634 				  "rx throttle %d\n", urb_status);
635 		}
636 block:
637 		state = rx_cleanup;
638 		entry->urb = urb;
639 		urb = NULL;
640 		break;
641 
642 	/* data overrun ... flush fifo? */
643 	case -EOVERFLOW:
644 		dev->net->stats.rx_over_errors++;
645 		fallthrough;
646 
647 	default:
648 		state = rx_cleanup;
649 		dev->net->stats.rx_errors++;
650 		netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
651 		break;
652 	}
653 
654 	/* stop rx if packet error rate is high */
655 	if (++dev->pkt_cnt > 30) {
656 		dev->pkt_cnt = 0;
657 		dev->pkt_err = 0;
658 	} else {
659 		if (state == rx_cleanup)
660 			dev->pkt_err++;
661 		if (dev->pkt_err > 20)
662 			set_bit(EVENT_RX_KILL, &dev->flags);
663 	}
664 
665 	state = defer_bh(dev, skb, &dev->rxq, state);
666 
667 	if (urb) {
668 		if (netif_running (dev->net) &&
669 		    !test_bit (EVENT_RX_HALT, &dev->flags) &&
670 		    state != unlink_start) {
671 			rx_submit (dev, urb, GFP_ATOMIC);
672 			usb_mark_last_busy(dev->udev);
673 			return;
674 		}
675 		usb_free_urb (urb);
676 	}
677 	netif_dbg(dev, rx_err, dev->net, "no read resubmitted\n");
678 }
679 
680 /*-------------------------------------------------------------------------*/
681 void usbnet_pause_rx(struct usbnet *dev)
682 {
683 	set_bit(EVENT_RX_PAUSED, &dev->flags);
684 
685 	netif_dbg(dev, rx_status, dev->net, "paused rx queue enabled\n");
686 }
687 EXPORT_SYMBOL_GPL(usbnet_pause_rx);
688 
689 void usbnet_resume_rx(struct usbnet *dev)
690 {
691 	struct sk_buff *skb;
692 	int num = 0;
693 
694 	clear_bit(EVENT_RX_PAUSED, &dev->flags);
695 
696 	while ((skb = skb_dequeue(&dev->rxq_pause)) != NULL) {
697 		usbnet_skb_return(dev, skb);
698 		num++;
699 	}
700 
701 	tasklet_schedule(&dev->bh);
702 
703 	netif_dbg(dev, rx_status, dev->net,
704 		  "paused rx queue disabled, %d skbs requeued\n", num);
705 }
706 EXPORT_SYMBOL_GPL(usbnet_resume_rx);
707 
708 void usbnet_purge_paused_rxq(struct usbnet *dev)
709 {
710 	skb_queue_purge(&dev->rxq_pause);
711 }
712 EXPORT_SYMBOL_GPL(usbnet_purge_paused_rxq);
713 
714 /*-------------------------------------------------------------------------*/
715 
716 // unlink pending rx/tx; completion handlers do all other cleanup
717 
718 static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
719 {
720 	unsigned long		flags;
721 	struct sk_buff		*skb;
722 	int			count = 0;
723 
724 	spin_lock_irqsave (&q->lock, flags);
725 	while (!skb_queue_empty(q)) {
726 		struct skb_data		*entry;
727 		struct urb		*urb;
728 		int			retval;
729 
730 		skb_queue_walk(q, skb) {
731 			entry = (struct skb_data *) skb->cb;
732 			if (entry->state != unlink_start)
733 				goto found;
734 		}
735 		break;
736 found:
737 		entry->state = unlink_start;
738 		urb = entry->urb;
739 
740 		/*
741 		 * Get reference count of the URB to avoid it to be
742 		 * freed during usb_unlink_urb, which may trigger
743 		 * use-after-free problem inside usb_unlink_urb since
744 		 * usb_unlink_urb is always racing with .complete
745 		 * handler(include defer_bh).
746 		 */
747 		usb_get_urb(urb);
748 		spin_unlock_irqrestore(&q->lock, flags);
749 		// during some PM-driven resume scenarios,
750 		// these (async) unlinks complete immediately
751 		retval = usb_unlink_urb (urb);
752 		if (retval != -EINPROGRESS && retval != 0)
753 			netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
754 		else
755 			count++;
756 		usb_put_urb(urb);
757 		spin_lock_irqsave(&q->lock, flags);
758 	}
759 	spin_unlock_irqrestore (&q->lock, flags);
760 	return count;
761 }
762 
763 // Flush all pending rx urbs
764 // minidrivers may need to do this when the MTU changes
765 
766 void usbnet_unlink_rx_urbs(struct usbnet *dev)
767 {
768 	if (netif_running(dev->net)) {
769 		(void) unlink_urbs (dev, &dev->rxq);
770 		tasklet_schedule(&dev->bh);
771 	}
772 }
773 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
774 
775 /*-------------------------------------------------------------------------*/
776 
777 static void wait_skb_queue_empty(struct sk_buff_head *q)
778 {
779 	unsigned long flags;
780 
781 	spin_lock_irqsave(&q->lock, flags);
782 	while (!skb_queue_empty(q)) {
783 		spin_unlock_irqrestore(&q->lock, flags);
784 		schedule_timeout(msecs_to_jiffies(UNLINK_TIMEOUT_MS));
785 		set_current_state(TASK_UNINTERRUPTIBLE);
786 		spin_lock_irqsave(&q->lock, flags);
787 	}
788 	spin_unlock_irqrestore(&q->lock, flags);
789 }
790 
791 // precondition: never called in_interrupt
792 static void usbnet_terminate_urbs(struct usbnet *dev)
793 {
794 	DECLARE_WAITQUEUE(wait, current);
795 	int temp;
796 
797 	/* ensure there are no more active urbs */
798 	add_wait_queue(&dev->wait, &wait);
799 	set_current_state(TASK_UNINTERRUPTIBLE);
800 	temp = unlink_urbs(dev, &dev->txq) +
801 		unlink_urbs(dev, &dev->rxq);
802 
803 	/* maybe wait for deletions to finish. */
804 	wait_skb_queue_empty(&dev->rxq);
805 	wait_skb_queue_empty(&dev->txq);
806 	wait_skb_queue_empty(&dev->done);
807 	netif_dbg(dev, ifdown, dev->net,
808 		  "waited for %d urb completions\n", temp);
809 	set_current_state(TASK_RUNNING);
810 	remove_wait_queue(&dev->wait, &wait);
811 }
812 
813 int usbnet_stop (struct net_device *net)
814 {
815 	struct usbnet		*dev = netdev_priv(net);
816 	const struct driver_info *info = dev->driver_info;
817 	int			retval, pm, mpn;
818 
819 	clear_bit(EVENT_DEV_OPEN, &dev->flags);
820 	netif_stop_queue (net);
821 
822 	netif_info(dev, ifdown, dev->net,
823 		   "stop stats: rx/tx %lu/%lu, errs %lu/%lu\n",
824 		   net->stats.rx_packets, net->stats.tx_packets,
825 		   net->stats.rx_errors, net->stats.tx_errors);
826 
827 	/* to not race resume */
828 	pm = usb_autopm_get_interface(dev->intf);
829 	/* allow minidriver to stop correctly (wireless devices to turn off
830 	 * radio etc) */
831 	if (info->stop) {
832 		retval = info->stop(dev);
833 		if (retval < 0)
834 			netif_info(dev, ifdown, dev->net,
835 				   "stop fail (%d) usbnet usb-%s-%s, %s\n",
836 				   retval,
837 				   dev->udev->bus->bus_name, dev->udev->devpath,
838 				   info->description);
839 	}
840 
841 	if (!(info->flags & FLAG_AVOID_UNLINK_URBS))
842 		usbnet_terminate_urbs(dev);
843 
844 	usbnet_status_stop(dev);
845 
846 	usbnet_purge_paused_rxq(dev);
847 
848 	mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
849 
850 	/* deferred work (timer, softirq, task) must also stop */
851 	dev->flags = 0;
852 	del_timer_sync(&dev->delay);
853 	tasklet_kill(&dev->bh);
854 	cancel_work_sync(&dev->kevent);
855 
856 	/* We have cyclic dependencies. Those calls are needed
857 	 * to break a cycle. We cannot fall into the gaps because
858 	 * we have a flag
859 	 */
860 	tasklet_kill(&dev->bh);
861 	del_timer_sync(&dev->delay);
862 	cancel_work_sync(&dev->kevent);
863 
864 	if (!pm)
865 		usb_autopm_put_interface(dev->intf);
866 
867 	if (info->manage_power && mpn)
868 		info->manage_power(dev, 0);
869 	else
870 		usb_autopm_put_interface(dev->intf);
871 
872 	return 0;
873 }
874 EXPORT_SYMBOL_GPL(usbnet_stop);
875 
876 /*-------------------------------------------------------------------------*/
877 
878 // posts reads, and enables write queuing
879 
880 // precondition: never called in_interrupt
881 
882 int usbnet_open (struct net_device *net)
883 {
884 	struct usbnet		*dev = netdev_priv(net);
885 	int			retval;
886 	const struct driver_info *info = dev->driver_info;
887 
888 	if ((retval = usb_autopm_get_interface(dev->intf)) < 0) {
889 		netif_info(dev, ifup, dev->net,
890 			   "resumption fail (%d) usbnet usb-%s-%s, %s\n",
891 			   retval,
892 			   dev->udev->bus->bus_name,
893 			   dev->udev->devpath,
894 			   info->description);
895 		goto done_nopm;
896 	}
897 
898 	// put into "known safe" state
899 	if (info->reset && (retval = info->reset (dev)) < 0) {
900 		netif_info(dev, ifup, dev->net,
901 			   "open reset fail (%d) usbnet usb-%s-%s, %s\n",
902 			   retval,
903 			   dev->udev->bus->bus_name,
904 			   dev->udev->devpath,
905 			   info->description);
906 		goto done;
907 	}
908 
909 	/* hard_mtu or rx_urb_size may change in reset() */
910 	usbnet_update_max_qlen(dev);
911 
912 	// insist peer be connected
913 	if (info->check_connect && (retval = info->check_connect (dev)) < 0) {
914 		netif_err(dev, ifup, dev->net, "can't open; %d\n", retval);
915 		goto done;
916 	}
917 
918 	/* start any status interrupt transfer */
919 	if (dev->interrupt) {
920 		retval = usbnet_status_start(dev, GFP_KERNEL);
921 		if (retval < 0) {
922 			netif_err(dev, ifup, dev->net,
923 				  "intr submit %d\n", retval);
924 			goto done;
925 		}
926 	}
927 
928 	set_bit(EVENT_DEV_OPEN, &dev->flags);
929 	netif_start_queue (net);
930 	netif_info(dev, ifup, dev->net,
931 		   "open: enable queueing (rx %d, tx %d) mtu %d %s framing\n",
932 		   (int)RX_QLEN(dev), (int)TX_QLEN(dev),
933 		   dev->net->mtu,
934 		   (dev->driver_info->flags & FLAG_FRAMING_NC) ? "NetChip" :
935 		   (dev->driver_info->flags & FLAG_FRAMING_GL) ? "GeneSys" :
936 		   (dev->driver_info->flags & FLAG_FRAMING_Z) ? "Zaurus" :
937 		   (dev->driver_info->flags & FLAG_FRAMING_RN) ? "RNDIS" :
938 		   (dev->driver_info->flags & FLAG_FRAMING_AX) ? "ASIX" :
939 		   "simple");
940 
941 	/* reset rx error state */
942 	dev->pkt_cnt = 0;
943 	dev->pkt_err = 0;
944 	clear_bit(EVENT_RX_KILL, &dev->flags);
945 
946 	// delay posting reads until we're fully open
947 	tasklet_schedule (&dev->bh);
948 	if (info->manage_power) {
949 		retval = info->manage_power(dev, 1);
950 		if (retval < 0) {
951 			retval = 0;
952 			set_bit(EVENT_NO_RUNTIME_PM, &dev->flags);
953 		} else {
954 			usb_autopm_put_interface(dev->intf);
955 		}
956 	}
957 	return retval;
958 done:
959 	usb_autopm_put_interface(dev->intf);
960 done_nopm:
961 	return retval;
962 }
963 EXPORT_SYMBOL_GPL(usbnet_open);
964 
965 /*-------------------------------------------------------------------------*/
966 
967 /* ethtool methods; minidrivers may need to add some more, but
968  * they'll probably want to use this base set.
969  */
970 
971 /* These methods are written on the assumption that the device
972  * uses MII
973  */
974 int usbnet_get_link_ksettings_mii(struct net_device *net,
975 			      struct ethtool_link_ksettings *cmd)
976 {
977 	struct usbnet *dev = netdev_priv(net);
978 
979 	if (!dev->mii.mdio_read)
980 		return -EOPNOTSUPP;
981 
982 	mii_ethtool_get_link_ksettings(&dev->mii, cmd);
983 
984 	return 0;
985 }
986 EXPORT_SYMBOL_GPL(usbnet_get_link_ksettings_mii);
987 
988 int usbnet_get_link_ksettings_internal(struct net_device *net,
989 					struct ethtool_link_ksettings *cmd)
990 {
991 	struct usbnet *dev = netdev_priv(net);
992 
993 	/* the assumption that speed is equal on tx and rx
994 	 * is deeply engrained into the networking layer.
995 	 * For wireless stuff it is not true.
996 	 * We assume that rx_speed matters more.
997 	 */
998 	if (dev->rx_speed != SPEED_UNSET)
999 		cmd->base.speed = dev->rx_speed / 1000000;
1000 	else if (dev->tx_speed != SPEED_UNSET)
1001 		cmd->base.speed = dev->tx_speed / 1000000;
1002 	else
1003 		cmd->base.speed = SPEED_UNKNOWN;
1004 
1005 	return 0;
1006 }
1007 EXPORT_SYMBOL_GPL(usbnet_get_link_ksettings_internal);
1008 
1009 int usbnet_set_link_ksettings_mii(struct net_device *net,
1010 			      const struct ethtool_link_ksettings *cmd)
1011 {
1012 	struct usbnet *dev = netdev_priv(net);
1013 	int retval;
1014 
1015 	if (!dev->mii.mdio_write)
1016 		return -EOPNOTSUPP;
1017 
1018 	retval = mii_ethtool_set_link_ksettings(&dev->mii, cmd);
1019 
1020 	/* link speed/duplex might have changed */
1021 	if (dev->driver_info->link_reset)
1022 		dev->driver_info->link_reset(dev);
1023 
1024 	/* hard_mtu or rx_urb_size may change in link_reset() */
1025 	usbnet_update_max_qlen(dev);
1026 
1027 	return retval;
1028 }
1029 EXPORT_SYMBOL_GPL(usbnet_set_link_ksettings_mii);
1030 
1031 u32 usbnet_get_link (struct net_device *net)
1032 {
1033 	struct usbnet *dev = netdev_priv(net);
1034 
1035 	/* If a check_connect is defined, return its result */
1036 	if (dev->driver_info->check_connect)
1037 		return dev->driver_info->check_connect (dev) == 0;
1038 
1039 	/* if the device has mii operations, use those */
1040 	if (dev->mii.mdio_read)
1041 		return mii_link_ok(&dev->mii);
1042 
1043 	/* Otherwise, dtrt for drivers calling netif_carrier_{on,off} */
1044 	return ethtool_op_get_link(net);
1045 }
1046 EXPORT_SYMBOL_GPL(usbnet_get_link);
1047 
1048 int usbnet_nway_reset(struct net_device *net)
1049 {
1050 	struct usbnet *dev = netdev_priv(net);
1051 
1052 	if (!dev->mii.mdio_write)
1053 		return -EOPNOTSUPP;
1054 
1055 	return mii_nway_restart(&dev->mii);
1056 }
1057 EXPORT_SYMBOL_GPL(usbnet_nway_reset);
1058 
1059 void usbnet_get_drvinfo (struct net_device *net, struct ethtool_drvinfo *info)
1060 {
1061 	struct usbnet *dev = netdev_priv(net);
1062 
1063 	strscpy(info->driver, dev->driver_name, sizeof(info->driver));
1064 	strscpy(info->fw_version, dev->driver_info->description,
1065 		sizeof(info->fw_version));
1066 	usb_make_path (dev->udev, info->bus_info, sizeof info->bus_info);
1067 }
1068 EXPORT_SYMBOL_GPL(usbnet_get_drvinfo);
1069 
1070 u32 usbnet_get_msglevel (struct net_device *net)
1071 {
1072 	struct usbnet *dev = netdev_priv(net);
1073 
1074 	return dev->msg_enable;
1075 }
1076 EXPORT_SYMBOL_GPL(usbnet_get_msglevel);
1077 
1078 void usbnet_set_msglevel (struct net_device *net, u32 level)
1079 {
1080 	struct usbnet *dev = netdev_priv(net);
1081 
1082 	dev->msg_enable = level;
1083 }
1084 EXPORT_SYMBOL_GPL(usbnet_set_msglevel);
1085 
1086 /* drivers may override default ethtool_ops in their bind() routine */
1087 static const struct ethtool_ops usbnet_ethtool_ops = {
1088 	.get_link		= usbnet_get_link,
1089 	.nway_reset		= usbnet_nway_reset,
1090 	.get_drvinfo		= usbnet_get_drvinfo,
1091 	.get_msglevel		= usbnet_get_msglevel,
1092 	.set_msglevel		= usbnet_set_msglevel,
1093 	.get_ts_info		= ethtool_op_get_ts_info,
1094 	.get_link_ksettings	= usbnet_get_link_ksettings_mii,
1095 	.set_link_ksettings	= usbnet_set_link_ksettings_mii,
1096 };
1097 
1098 /*-------------------------------------------------------------------------*/
1099 
1100 static void __handle_link_change(struct usbnet *dev)
1101 {
1102 	if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
1103 		return;
1104 
1105 	if (!netif_carrier_ok(dev->net)) {
1106 		/* kill URBs for reading packets to save bus bandwidth */
1107 		unlink_urbs(dev, &dev->rxq);
1108 
1109 		/*
1110 		 * tx_timeout will unlink URBs for sending packets and
1111 		 * tx queue is stopped by netcore after link becomes off
1112 		 */
1113 	} else {
1114 		/* submitting URBs for reading packets */
1115 		tasklet_schedule(&dev->bh);
1116 	}
1117 
1118 	/* hard_mtu or rx_urb_size may change during link change */
1119 	usbnet_update_max_qlen(dev);
1120 
1121 	clear_bit(EVENT_LINK_CHANGE, &dev->flags);
1122 }
1123 
1124 void usbnet_set_rx_mode(struct net_device *net)
1125 {
1126 	struct usbnet		*dev = netdev_priv(net);
1127 
1128 	usbnet_defer_kevent(dev, EVENT_SET_RX_MODE);
1129 }
1130 EXPORT_SYMBOL_GPL(usbnet_set_rx_mode);
1131 
1132 static void __handle_set_rx_mode(struct usbnet *dev)
1133 {
1134 	if (dev->driver_info->set_rx_mode)
1135 		(dev->driver_info->set_rx_mode)(dev);
1136 
1137 	clear_bit(EVENT_SET_RX_MODE, &dev->flags);
1138 }
1139 
1140 /* work that cannot be done in interrupt context uses keventd.
1141  *
1142  * NOTE:  with 2.5 we could do more of this using completion callbacks,
1143  * especially now that control transfers can be queued.
1144  */
1145 static void
1146 usbnet_deferred_kevent (struct work_struct *work)
1147 {
1148 	struct usbnet		*dev =
1149 		container_of(work, struct usbnet, kevent);
1150 	int			status;
1151 
1152 	/* usb_clear_halt() needs a thread context */
1153 	if (test_bit (EVENT_TX_HALT, &dev->flags)) {
1154 		unlink_urbs (dev, &dev->txq);
1155 		status = usb_autopm_get_interface(dev->intf);
1156 		if (status < 0)
1157 			goto fail_pipe;
1158 		status = usb_clear_halt (dev->udev, dev->out);
1159 		usb_autopm_put_interface(dev->intf);
1160 		if (status < 0 &&
1161 		    status != -EPIPE &&
1162 		    status != -ESHUTDOWN) {
1163 			if (netif_msg_tx_err (dev))
1164 fail_pipe:
1165 				netdev_err(dev->net, "can't clear tx halt, status %d\n",
1166 					   status);
1167 		} else {
1168 			clear_bit (EVENT_TX_HALT, &dev->flags);
1169 			if (status != -ESHUTDOWN)
1170 				netif_wake_queue (dev->net);
1171 		}
1172 	}
1173 	if (test_bit (EVENT_RX_HALT, &dev->flags)) {
1174 		unlink_urbs (dev, &dev->rxq);
1175 		status = usb_autopm_get_interface(dev->intf);
1176 		if (status < 0)
1177 			goto fail_halt;
1178 		status = usb_clear_halt (dev->udev, dev->in);
1179 		usb_autopm_put_interface(dev->intf);
1180 		if (status < 0 &&
1181 		    status != -EPIPE &&
1182 		    status != -ESHUTDOWN) {
1183 			if (netif_msg_rx_err (dev))
1184 fail_halt:
1185 				netdev_err(dev->net, "can't clear rx halt, status %d\n",
1186 					   status);
1187 		} else {
1188 			clear_bit (EVENT_RX_HALT, &dev->flags);
1189 			if (!usbnet_going_away(dev))
1190 				tasklet_schedule(&dev->bh);
1191 		}
1192 	}
1193 
1194 	/* tasklet could resubmit itself forever if memory is tight */
1195 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
1196 		struct urb	*urb = NULL;
1197 		int resched = 1;
1198 
1199 		if (netif_running (dev->net))
1200 			urb = usb_alloc_urb (0, GFP_KERNEL);
1201 		else
1202 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1203 		if (urb != NULL) {
1204 			clear_bit (EVENT_RX_MEMORY, &dev->flags);
1205 			status = usb_autopm_get_interface(dev->intf);
1206 			if (status < 0) {
1207 				usb_free_urb(urb);
1208 				goto fail_lowmem;
1209 			}
1210 			if (rx_submit (dev, urb, GFP_KERNEL) == -ENOLINK)
1211 				resched = 0;
1212 			usb_autopm_put_interface(dev->intf);
1213 fail_lowmem:
1214 			if (resched)
1215 				if (!usbnet_going_away(dev))
1216 					tasklet_schedule(&dev->bh);
1217 		}
1218 	}
1219 
1220 	if (test_bit (EVENT_LINK_RESET, &dev->flags)) {
1221 		const struct driver_info *info = dev->driver_info;
1222 		int			retval = 0;
1223 
1224 		clear_bit (EVENT_LINK_RESET, &dev->flags);
1225 		status = usb_autopm_get_interface(dev->intf);
1226 		if (status < 0)
1227 			goto skip_reset;
1228 		if(info->link_reset && (retval = info->link_reset(dev)) < 0) {
1229 			usb_autopm_put_interface(dev->intf);
1230 skip_reset:
1231 			netdev_info(dev->net, "link reset failed (%d) usbnet usb-%s-%s, %s\n",
1232 				    retval,
1233 				    dev->udev->bus->bus_name,
1234 				    dev->udev->devpath,
1235 				    info->description);
1236 		} else {
1237 			usb_autopm_put_interface(dev->intf);
1238 		}
1239 
1240 		/* handle link change from link resetting */
1241 		__handle_link_change(dev);
1242 	}
1243 
1244 	if (test_bit (EVENT_LINK_CHANGE, &dev->flags))
1245 		__handle_link_change(dev);
1246 
1247 	if (test_bit (EVENT_SET_RX_MODE, &dev->flags))
1248 		__handle_set_rx_mode(dev);
1249 
1250 
1251 	if (dev->flags)
1252 		netdev_dbg(dev->net, "kevent done, flags = 0x%lx\n", dev->flags);
1253 }
1254 
1255 /*-------------------------------------------------------------------------*/
1256 
1257 static void tx_complete (struct urb *urb)
1258 {
1259 	struct sk_buff		*skb = (struct sk_buff *) urb->context;
1260 	struct skb_data		*entry = (struct skb_data *) skb->cb;
1261 	struct usbnet		*dev = entry->dev;
1262 
1263 	if (urb->status == 0) {
1264 		struct pcpu_sw_netstats *stats64 = this_cpu_ptr(dev->net->tstats);
1265 		unsigned long flags;
1266 
1267 		flags = u64_stats_update_begin_irqsave(&stats64->syncp);
1268 		u64_stats_add(&stats64->tx_packets, entry->packets);
1269 		u64_stats_add(&stats64->tx_bytes, entry->length);
1270 		u64_stats_update_end_irqrestore(&stats64->syncp, flags);
1271 	} else {
1272 		dev->net->stats.tx_errors++;
1273 
1274 		switch (urb->status) {
1275 		case -EPIPE:
1276 			usbnet_defer_kevent (dev, EVENT_TX_HALT);
1277 			break;
1278 
1279 		/* software-driven interface shutdown */
1280 		case -ECONNRESET:		// async unlink
1281 		case -ESHUTDOWN:		// hardware gone
1282 			break;
1283 
1284 		/* like rx, tx gets controller i/o faults during hub_wq
1285 		 * delays and so it uses the same throttling mechanism.
1286 		 */
1287 		case -EPROTO:
1288 		case -ETIME:
1289 		case -EILSEQ:
1290 			usb_mark_last_busy(dev->udev);
1291 			if (!timer_pending (&dev->delay)) {
1292 				mod_timer (&dev->delay,
1293 					jiffies + THROTTLE_JIFFIES);
1294 				netif_dbg(dev, link, dev->net,
1295 					  "tx throttle %d\n", urb->status);
1296 			}
1297 			netif_stop_queue (dev->net);
1298 			break;
1299 		default:
1300 			netif_dbg(dev, tx_err, dev->net,
1301 				  "tx err %d\n", entry->urb->status);
1302 			break;
1303 		}
1304 	}
1305 
1306 	usb_autopm_put_interface_async(dev->intf);
1307 	(void) defer_bh(dev, skb, &dev->txq, tx_done);
1308 }
1309 
1310 /*-------------------------------------------------------------------------*/
1311 
1312 void usbnet_tx_timeout (struct net_device *net, unsigned int txqueue)
1313 {
1314 	struct usbnet		*dev = netdev_priv(net);
1315 
1316 	unlink_urbs (dev, &dev->txq);
1317 	tasklet_schedule (&dev->bh);
1318 	/* this needs to be handled individually because the generic layer
1319 	 * doesn't know what is sufficient and could not restore private
1320 	 * information if a remedy of an unconditional reset were used.
1321 	 */
1322 	if (dev->driver_info->recover)
1323 		(dev->driver_info->recover)(dev);
1324 }
1325 EXPORT_SYMBOL_GPL(usbnet_tx_timeout);
1326 
1327 /*-------------------------------------------------------------------------*/
1328 
1329 static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
1330 {
1331 	unsigned num_sgs, total_len = 0;
1332 	int i, s = 0;
1333 
1334 	num_sgs = skb_shinfo(skb)->nr_frags + 1;
1335 	if (num_sgs == 1)
1336 		return 0;
1337 
1338 	/* reserve one for zero packet */
1339 	urb->sg = kmalloc_array(num_sgs + 1, sizeof(struct scatterlist),
1340 				GFP_ATOMIC);
1341 	if (!urb->sg)
1342 		return -ENOMEM;
1343 
1344 	urb->num_sgs = num_sgs;
1345 	sg_init_table(urb->sg, urb->num_sgs + 1);
1346 
1347 	sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb));
1348 	total_len += skb_headlen(skb);
1349 
1350 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1351 		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1352 
1353 		total_len += skb_frag_size(f);
1354 		sg_set_page(&urb->sg[i + s], skb_frag_page(f), skb_frag_size(f),
1355 			    skb_frag_off(f));
1356 	}
1357 	urb->transfer_buffer_length = total_len;
1358 
1359 	return 1;
1360 }
1361 
1362 netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
1363 				     struct net_device *net)
1364 {
1365 	struct usbnet		*dev = netdev_priv(net);
1366 	unsigned int			length;
1367 	struct urb		*urb = NULL;
1368 	struct skb_data		*entry;
1369 	const struct driver_info *info = dev->driver_info;
1370 	unsigned long		flags;
1371 	int retval;
1372 
1373 	if (skb)
1374 		skb_tx_timestamp(skb);
1375 
1376 	// some devices want funky USB-level framing, for
1377 	// win32 driver (usually) and/or hardware quirks
1378 	if (info->tx_fixup) {
1379 		skb = info->tx_fixup (dev, skb, GFP_ATOMIC);
1380 		if (!skb) {
1381 			/* packet collected; minidriver waiting for more */
1382 			if (info->flags & FLAG_MULTI_PACKET)
1383 				goto not_drop;
1384 			netif_dbg(dev, tx_err, dev->net, "can't tx_fixup skb\n");
1385 			goto drop;
1386 		}
1387 	}
1388 
1389 	if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) {
1390 		netif_dbg(dev, tx_err, dev->net, "no urb\n");
1391 		goto drop;
1392 	}
1393 
1394 	entry = (struct skb_data *) skb->cb;
1395 	entry->urb = urb;
1396 	entry->dev = dev;
1397 
1398 	usb_fill_bulk_urb (urb, dev->udev, dev->out,
1399 			skb->data, skb->len, tx_complete, skb);
1400 	if (dev->can_dma_sg) {
1401 		if (build_dma_sg(skb, urb) < 0)
1402 			goto drop;
1403 	}
1404 	length = urb->transfer_buffer_length;
1405 
1406 	/* don't assume the hardware handles USB_ZERO_PACKET
1407 	 * NOTE:  strictly conforming cdc-ether devices should expect
1408 	 * the ZLP here, but ignore the one-byte packet.
1409 	 * NOTE2: CDC NCM specification is different from CDC ECM when
1410 	 * handling ZLP/short packets, so cdc_ncm driver will make short
1411 	 * packet itself if needed.
1412 	 */
1413 	if (length % dev->maxpacket == 0) {
1414 		if (!(info->flags & FLAG_SEND_ZLP)) {
1415 			if (!(info->flags & FLAG_MULTI_PACKET)) {
1416 				length++;
1417 				if (skb_tailroom(skb) && !urb->num_sgs) {
1418 					skb->data[skb->len] = 0;
1419 					__skb_put(skb, 1);
1420 				} else if (urb->num_sgs)
1421 					sg_set_buf(&urb->sg[urb->num_sgs++],
1422 							dev->padding_pkt, 1);
1423 			}
1424 		} else
1425 			urb->transfer_flags |= URB_ZERO_PACKET;
1426 	}
1427 	urb->transfer_buffer_length = length;
1428 
1429 	if (info->flags & FLAG_MULTI_PACKET) {
1430 		/* Driver has set number of packets and a length delta.
1431 		 * Calculate the complete length and ensure that it's
1432 		 * positive.
1433 		 */
1434 		entry->length += length;
1435 		if (WARN_ON_ONCE(entry->length <= 0))
1436 			entry->length = length;
1437 	} else {
1438 		usbnet_set_skb_tx_stats(skb, 1, length);
1439 	}
1440 
1441 	spin_lock_irqsave(&dev->txq.lock, flags);
1442 	retval = usb_autopm_get_interface_async(dev->intf);
1443 	if (retval < 0) {
1444 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1445 		goto drop;
1446 	}
1447 	if (netif_queue_stopped(net)) {
1448 		usb_autopm_put_interface_async(dev->intf);
1449 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1450 		goto drop;
1451 	}
1452 
1453 #ifdef CONFIG_PM
1454 	/* if this triggers the device is still a sleep */
1455 	if (test_bit(EVENT_DEV_ASLEEP, &dev->flags)) {
1456 		/* transmission will be done in resume */
1457 		usb_anchor_urb(urb, &dev->deferred);
1458 		/* no use to process more packets */
1459 		netif_stop_queue(net);
1460 		usb_put_urb(urb);
1461 		spin_unlock_irqrestore(&dev->txq.lock, flags);
1462 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
1463 		goto deferred;
1464 	}
1465 #endif
1466 
1467 	switch ((retval = usb_submit_urb (urb, GFP_ATOMIC))) {
1468 	case -EPIPE:
1469 		netif_stop_queue (net);
1470 		usbnet_defer_kevent (dev, EVENT_TX_HALT);
1471 		usb_autopm_put_interface_async(dev->intf);
1472 		break;
1473 	default:
1474 		usb_autopm_put_interface_async(dev->intf);
1475 		netif_dbg(dev, tx_err, dev->net,
1476 			  "tx: submit urb err %d\n", retval);
1477 		break;
1478 	case 0:
1479 		netif_trans_update(net);
1480 		__usbnet_queue_skb(&dev->txq, skb, tx_start);
1481 		if (dev->txq.qlen >= TX_QLEN (dev))
1482 			netif_stop_queue (net);
1483 	}
1484 	spin_unlock_irqrestore (&dev->txq.lock, flags);
1485 
1486 	if (retval) {
1487 		netif_dbg(dev, tx_err, dev->net, "drop, code %d\n", retval);
1488 drop:
1489 		dev->net->stats.tx_dropped++;
1490 not_drop:
1491 		if (skb)
1492 			dev_kfree_skb_any (skb);
1493 		if (urb) {
1494 			kfree(urb->sg);
1495 			usb_free_urb(urb);
1496 		}
1497 	} else
1498 		netif_dbg(dev, tx_queued, dev->net,
1499 			  "> tx, len %u, type 0x%x\n", length, skb->protocol);
1500 #ifdef CONFIG_PM
1501 deferred:
1502 #endif
1503 	return NETDEV_TX_OK;
1504 }
1505 EXPORT_SYMBOL_GPL(usbnet_start_xmit);
1506 
1507 static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
1508 {
1509 	struct urb	*urb;
1510 	int		i;
1511 	int		ret = 0;
1512 
1513 	/* don't refill the queue all at once */
1514 	for (i = 0; i < 10 && dev->rxq.qlen < RX_QLEN(dev); i++) {
1515 		urb = usb_alloc_urb(0, flags);
1516 		if (urb != NULL) {
1517 			ret = rx_submit(dev, urb, flags);
1518 			if (ret)
1519 				goto err;
1520 		} else {
1521 			ret = -ENOMEM;
1522 			goto err;
1523 		}
1524 	}
1525 err:
1526 	return ret;
1527 }
1528 
1529 static inline void usb_free_skb(struct sk_buff *skb)
1530 {
1531 	struct skb_data *entry = (struct skb_data *)skb->cb;
1532 
1533 	usb_free_urb(entry->urb);
1534 	dev_kfree_skb(skb);
1535 }
1536 
1537 /*-------------------------------------------------------------------------*/
1538 
1539 // tasklet (work deferred from completions, in_irq) or timer
1540 
1541 static void usbnet_bh (struct timer_list *t)
1542 {
1543 	struct usbnet		*dev = from_timer(dev, t, delay);
1544 	struct sk_buff		*skb;
1545 	struct skb_data		*entry;
1546 
1547 	while ((skb = skb_dequeue (&dev->done))) {
1548 		entry = (struct skb_data *) skb->cb;
1549 		switch (entry->state) {
1550 		case rx_done:
1551 			if (rx_process(dev, skb))
1552 				usb_free_skb(skb);
1553 			continue;
1554 		case tx_done:
1555 			kfree(entry->urb->sg);
1556 			fallthrough;
1557 		case rx_cleanup:
1558 			usb_free_skb(skb);
1559 			continue;
1560 		default:
1561 			netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
1562 		}
1563 	}
1564 
1565 	/* restart RX again after disabling due to high error rate */
1566 	clear_bit(EVENT_RX_KILL, &dev->flags);
1567 
1568 	/* waiting for all pending urbs to complete?
1569 	 * only then can we forgo submitting anew
1570 	 */
1571 	if (waitqueue_active(&dev->wait)) {
1572 		if (dev->txq.qlen + dev->rxq.qlen + dev->done.qlen == 0)
1573 			wake_up_all(&dev->wait);
1574 
1575 	// or are we maybe short a few urbs?
1576 	} else if (netif_running (dev->net) &&
1577 		   netif_device_present (dev->net) &&
1578 		   netif_carrier_ok(dev->net) &&
1579 		   !usbnet_going_away(dev) &&
1580 		   !timer_pending(&dev->delay) &&
1581 		   !test_bit(EVENT_RX_PAUSED, &dev->flags) &&
1582 		   !test_bit(EVENT_RX_HALT, &dev->flags)) {
1583 		int	temp = dev->rxq.qlen;
1584 
1585 		if (temp < RX_QLEN(dev)) {
1586 			if (rx_alloc_submit(dev, GFP_ATOMIC) == -ENOLINK)
1587 				return;
1588 			if (temp != dev->rxq.qlen)
1589 				netif_dbg(dev, link, dev->net,
1590 					  "rxqlen %d --> %d\n",
1591 					  temp, dev->rxq.qlen);
1592 			if (dev->rxq.qlen < RX_QLEN(dev))
1593 				tasklet_schedule (&dev->bh);
1594 		}
1595 		if (dev->txq.qlen < TX_QLEN (dev))
1596 			netif_wake_queue (dev->net);
1597 	}
1598 }
1599 
1600 static void usbnet_bh_tasklet(struct tasklet_struct *t)
1601 {
1602 	struct usbnet *dev = from_tasklet(dev, t, bh);
1603 
1604 	usbnet_bh(&dev->delay);
1605 }
1606 
1607 
1608 /*-------------------------------------------------------------------------
1609  *
1610  * USB Device Driver support
1611  *
1612  *-------------------------------------------------------------------------*/
1613 
1614 // precondition: never called in_interrupt
1615 
1616 void usbnet_disconnect (struct usb_interface *intf)
1617 {
1618 	struct usbnet		*dev;
1619 	struct usb_device	*xdev;
1620 	struct net_device	*net;
1621 	struct urb		*urb;
1622 
1623 	dev = usb_get_intfdata(intf);
1624 	usb_set_intfdata(intf, NULL);
1625 	if (!dev)
1626 		return;
1627 	usbnet_mark_going_away(dev);
1628 
1629 	xdev = interface_to_usbdev (intf);
1630 
1631 	netif_info(dev, probe, dev->net, "unregister '%s' usb-%s-%s, %s\n",
1632 		   intf->dev.driver->name,
1633 		   xdev->bus->bus_name, xdev->devpath,
1634 		   dev->driver_info->description);
1635 
1636 	net = dev->net;
1637 	unregister_netdev (net);
1638 
1639 	while ((urb = usb_get_from_anchor(&dev->deferred))) {
1640 		dev_kfree_skb(urb->context);
1641 		kfree(urb->sg);
1642 		usb_free_urb(urb);
1643 	}
1644 
1645 	if (dev->driver_info->unbind)
1646 		dev->driver_info->unbind(dev, intf);
1647 
1648 	usb_kill_urb(dev->interrupt);
1649 	usb_free_urb(dev->interrupt);
1650 	kfree(dev->padding_pkt);
1651 
1652 	free_percpu(net->tstats);
1653 	free_netdev(net);
1654 }
1655 EXPORT_SYMBOL_GPL(usbnet_disconnect);
1656 
1657 static const struct net_device_ops usbnet_netdev_ops = {
1658 	.ndo_open		= usbnet_open,
1659 	.ndo_stop		= usbnet_stop,
1660 	.ndo_start_xmit		= usbnet_start_xmit,
1661 	.ndo_tx_timeout		= usbnet_tx_timeout,
1662 	.ndo_set_rx_mode	= usbnet_set_rx_mode,
1663 	.ndo_change_mtu		= usbnet_change_mtu,
1664 	.ndo_get_stats64	= dev_get_tstats64,
1665 	.ndo_set_mac_address 	= eth_mac_addr,
1666 	.ndo_validate_addr	= eth_validate_addr,
1667 };
1668 
1669 /*-------------------------------------------------------------------------*/
1670 
1671 // precondition: never called in_interrupt
1672 
1673 static struct device_type wlan_type = {
1674 	.name	= "wlan",
1675 };
1676 
1677 static struct device_type wwan_type = {
1678 	.name	= "wwan",
1679 };
1680 
1681 int
1682 usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
1683 {
1684 	struct usbnet			*dev;
1685 	struct net_device		*net;
1686 	struct usb_host_interface	*interface;
1687 	const struct driver_info	*info;
1688 	struct usb_device		*xdev;
1689 	int				status;
1690 	const char			*name;
1691 	struct usb_driver 	*driver = to_usb_driver(udev->dev.driver);
1692 
1693 	/* usbnet already took usb runtime pm, so have to enable the feature
1694 	 * for usb interface, otherwise usb_autopm_get_interface may return
1695 	 * failure if RUNTIME_PM is enabled.
1696 	 */
1697 	if (!driver->supports_autosuspend) {
1698 		driver->supports_autosuspend = 1;
1699 		pm_runtime_enable(&udev->dev);
1700 	}
1701 
1702 	name = udev->dev.driver->name;
1703 	info = (const struct driver_info *) prod->driver_info;
1704 	if (!info) {
1705 		dev_dbg (&udev->dev, "blacklisted by %s\n", name);
1706 		return -ENODEV;
1707 	}
1708 	xdev = interface_to_usbdev (udev);
1709 	interface = udev->cur_altsetting;
1710 
1711 	status = -ENOMEM;
1712 
1713 	// set up our own records
1714 	net = alloc_etherdev(sizeof(*dev));
1715 	if (!net)
1716 		goto out;
1717 
1718 	/* netdev_printk() needs this so do it as early as possible */
1719 	SET_NETDEV_DEV(net, &udev->dev);
1720 
1721 	dev = netdev_priv(net);
1722 	dev->udev = xdev;
1723 	dev->intf = udev;
1724 	dev->driver_info = info;
1725 	dev->driver_name = name;
1726 	dev->rx_speed = SPEED_UNSET;
1727 	dev->tx_speed = SPEED_UNSET;
1728 
1729 	net->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
1730 	if (!net->tstats)
1731 		goto out0;
1732 
1733 	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV
1734 				| NETIF_MSG_PROBE | NETIF_MSG_LINK);
1735 	init_waitqueue_head(&dev->wait);
1736 	skb_queue_head_init (&dev->rxq);
1737 	skb_queue_head_init (&dev->txq);
1738 	skb_queue_head_init (&dev->done);
1739 	skb_queue_head_init(&dev->rxq_pause);
1740 	tasklet_setup(&dev->bh, usbnet_bh_tasklet);
1741 	INIT_WORK (&dev->kevent, usbnet_deferred_kevent);
1742 	init_usb_anchor(&dev->deferred);
1743 	timer_setup(&dev->delay, usbnet_bh, 0);
1744 	mutex_init (&dev->phy_mutex);
1745 	mutex_init(&dev->interrupt_mutex);
1746 	dev->interrupt_count = 0;
1747 
1748 	dev->net = net;
1749 	strscpy(net->name, "usb%d", sizeof(net->name));
1750 
1751 	/* rx and tx sides can use different message sizes;
1752 	 * bind() should set rx_urb_size in that case.
1753 	 */
1754 	dev->hard_mtu = net->mtu + net->hard_header_len;
1755 	net->min_mtu = 0;
1756 	net->max_mtu = ETH_MAX_MTU;
1757 
1758 	net->netdev_ops = &usbnet_netdev_ops;
1759 	net->watchdog_timeo = TX_TIMEOUT_JIFFIES;
1760 	net->ethtool_ops = &usbnet_ethtool_ops;
1761 
1762 	// allow device-specific bind/init procedures
1763 	// NOTE net->name still not usable ...
1764 	if (info->bind) {
1765 		status = info->bind (dev, udev);
1766 		if (status < 0)
1767 			goto out1;
1768 
1769 		// heuristic:  "usb%d" for links we know are two-host,
1770 		// else "eth%d" when there's reasonable doubt.  userspace
1771 		// can rename the link if it knows better.
1772 		if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
1773 		    ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
1774 		     /* somebody touched it*/
1775 		     !is_zero_ether_addr(net->dev_addr)))
1776 			strscpy(net->name, "eth%d", sizeof(net->name));
1777 		/* WLAN devices should always be named "wlan%d" */
1778 		if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1779 			strscpy(net->name, "wlan%d", sizeof(net->name));
1780 		/* WWAN devices should always be named "wwan%d" */
1781 		if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1782 			strscpy(net->name, "wwan%d", sizeof(net->name));
1783 
1784 		/* devices that cannot do ARP */
1785 		if ((dev->driver_info->flags & FLAG_NOARP) != 0)
1786 			net->flags |= IFF_NOARP;
1787 
1788 		/* maybe the remote can't receive an Ethernet MTU */
1789 		if (net->mtu > (dev->hard_mtu - net->hard_header_len))
1790 			net->mtu = dev->hard_mtu - net->hard_header_len;
1791 	} else if (!info->in || !info->out)
1792 		status = usbnet_get_endpoints (dev, udev);
1793 	else {
1794 		u8 ep_addrs[3] = {
1795 			info->in + USB_DIR_IN, info->out + USB_DIR_OUT, 0
1796 		};
1797 
1798 		dev->in = usb_rcvbulkpipe (xdev, info->in);
1799 		dev->out = usb_sndbulkpipe (xdev, info->out);
1800 		if (!(info->flags & FLAG_NO_SETINT))
1801 			status = usb_set_interface (xdev,
1802 				interface->desc.bInterfaceNumber,
1803 				interface->desc.bAlternateSetting);
1804 		else
1805 			status = 0;
1806 
1807 		if (status == 0 && !usb_check_bulk_endpoints(udev, ep_addrs))
1808 			status = -EINVAL;
1809 	}
1810 	if (status >= 0 && dev->status)
1811 		status = init_status (dev, udev);
1812 	if (status < 0)
1813 		goto out3;
1814 
1815 	if (!dev->rx_urb_size)
1816 		dev->rx_urb_size = dev->hard_mtu;
1817 	dev->maxpacket = usb_maxpacket(dev->udev, dev->out);
1818 	if (dev->maxpacket == 0) {
1819 		/* that is a broken device */
1820 		status = -ENODEV;
1821 		goto out4;
1822 	}
1823 
1824 	/* this flags the device for user space */
1825 	if (!is_valid_ether_addr(net->dev_addr))
1826 		eth_hw_addr_random(net);
1827 
1828 	if ((dev->driver_info->flags & FLAG_WLAN) != 0)
1829 		SET_NETDEV_DEVTYPE(net, &wlan_type);
1830 	if ((dev->driver_info->flags & FLAG_WWAN) != 0)
1831 		SET_NETDEV_DEVTYPE(net, &wwan_type);
1832 
1833 	/* initialize max rx_qlen and tx_qlen */
1834 	usbnet_update_max_qlen(dev);
1835 
1836 	if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
1837 		!(info->flags & FLAG_MULTI_PACKET)) {
1838 		dev->padding_pkt = kzalloc(1, GFP_KERNEL);
1839 		if (!dev->padding_pkt) {
1840 			status = -ENOMEM;
1841 			goto out4;
1842 		}
1843 	}
1844 
1845 	status = register_netdev (net);
1846 	if (status)
1847 		goto out5;
1848 	netif_info(dev, probe, dev->net,
1849 		   "register '%s' at usb-%s-%s, %s, %pM\n",
1850 		   udev->dev.driver->name,
1851 		   xdev->bus->bus_name, xdev->devpath,
1852 		   dev->driver_info->description,
1853 		   net->dev_addr);
1854 
1855 	// ok, it's ready to go.
1856 	usb_set_intfdata (udev, dev);
1857 
1858 	netif_device_attach (net);
1859 
1860 	if (dev->driver_info->flags & FLAG_LINK_INTR)
1861 		usbnet_link_change(dev, 0, 0);
1862 
1863 	return 0;
1864 
1865 out5:
1866 	kfree(dev->padding_pkt);
1867 out4:
1868 	usb_free_urb(dev->interrupt);
1869 out3:
1870 	if (info->unbind)
1871 		info->unbind (dev, udev);
1872 out1:
1873 	/* subdrivers must undo all they did in bind() if they
1874 	 * fail it, but we may fail later and a deferred kevent
1875 	 * may trigger an error resubmitting itself and, worse,
1876 	 * schedule a timer. So we kill it all just in case.
1877 	 */
1878 	usbnet_mark_going_away(dev);
1879 	cancel_work_sync(&dev->kevent);
1880 	del_timer_sync(&dev->delay);
1881 	free_percpu(net->tstats);
1882 out0:
1883 	free_netdev(net);
1884 out:
1885 	return status;
1886 }
1887 EXPORT_SYMBOL_GPL(usbnet_probe);
1888 
1889 /*-------------------------------------------------------------------------*/
1890 
1891 /*
1892  * suspend the whole driver as soon as the first interface is suspended
1893  * resume only when the last interface is resumed
1894  */
1895 
1896 int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
1897 {
1898 	struct usbnet		*dev = usb_get_intfdata(intf);
1899 
1900 	if (!dev->suspend_count++) {
1901 		spin_lock_irq(&dev->txq.lock);
1902 		/* don't autosuspend while transmitting */
1903 		if (dev->txq.qlen && PMSG_IS_AUTO(message)) {
1904 			dev->suspend_count--;
1905 			spin_unlock_irq(&dev->txq.lock);
1906 			return -EBUSY;
1907 		} else {
1908 			set_bit(EVENT_DEV_ASLEEP, &dev->flags);
1909 			spin_unlock_irq(&dev->txq.lock);
1910 		}
1911 		/*
1912 		 * accelerate emptying of the rx and queues, to avoid
1913 		 * having everything error out.
1914 		 */
1915 		netif_device_detach (dev->net);
1916 		usbnet_terminate_urbs(dev);
1917 		__usbnet_status_stop_force(dev);
1918 
1919 		/*
1920 		 * reattach so runtime management can use and
1921 		 * wake the device
1922 		 */
1923 		netif_device_attach (dev->net);
1924 	}
1925 	return 0;
1926 }
1927 EXPORT_SYMBOL_GPL(usbnet_suspend);
1928 
1929 int usbnet_resume (struct usb_interface *intf)
1930 {
1931 	struct usbnet		*dev = usb_get_intfdata(intf);
1932 	struct sk_buff          *skb;
1933 	struct urb              *res;
1934 	int                     retval;
1935 
1936 	if (!--dev->suspend_count) {
1937 		/* resume interrupt URB if it was previously submitted */
1938 		__usbnet_status_start_force(dev, GFP_NOIO);
1939 
1940 		spin_lock_irq(&dev->txq.lock);
1941 		while ((res = usb_get_from_anchor(&dev->deferred))) {
1942 
1943 			skb = (struct sk_buff *)res->context;
1944 			retval = usb_submit_urb(res, GFP_ATOMIC);
1945 			if (retval < 0) {
1946 				dev_kfree_skb_any(skb);
1947 				kfree(res->sg);
1948 				usb_free_urb(res);
1949 				usb_autopm_put_interface_async(dev->intf);
1950 			} else {
1951 				netif_trans_update(dev->net);
1952 				__skb_queue_tail(&dev->txq, skb);
1953 			}
1954 		}
1955 
1956 		smp_mb();
1957 		clear_bit(EVENT_DEV_ASLEEP, &dev->flags);
1958 		spin_unlock_irq(&dev->txq.lock);
1959 
1960 		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {
1961 			/* handle remote wakeup ASAP
1962 			 * we cannot race against stop
1963 			 */
1964 			if (netif_device_present(dev->net) &&
1965 				!timer_pending(&dev->delay) &&
1966 				!test_bit(EVENT_RX_HALT, &dev->flags))
1967 					rx_alloc_submit(dev, GFP_NOIO);
1968 
1969 			if (!(dev->txq.qlen >= TX_QLEN(dev)))
1970 				netif_tx_wake_all_queues(dev->net);
1971 			tasklet_schedule (&dev->bh);
1972 		}
1973 	}
1974 
1975 	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
1976 		usb_autopm_get_interface_no_resume(intf);
1977 
1978 	return 0;
1979 }
1980 EXPORT_SYMBOL_GPL(usbnet_resume);
1981 
1982 /*
1983  * Either a subdriver implements manage_power, then it is assumed to always
1984  * be ready to be suspended or it reports the readiness to be suspended
1985  * explicitly
1986  */
1987 void usbnet_device_suggests_idle(struct usbnet *dev)
1988 {
1989 	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
1990 		dev->intf->needs_remote_wakeup = 1;
1991 		usb_autopm_put_interface_async(dev->intf);
1992 	}
1993 }
1994 EXPORT_SYMBOL(usbnet_device_suggests_idle);
1995 
1996 /*
1997  * For devices that can do without special commands
1998  */
1999 int usbnet_manage_power(struct usbnet *dev, int on)
2000 {
2001 	dev->intf->needs_remote_wakeup = on;
2002 	return 0;
2003 }
2004 EXPORT_SYMBOL(usbnet_manage_power);
2005 
2006 void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
2007 {
2008 	/* update link after link is reseted */
2009 	if (link && !need_reset)
2010 		netif_carrier_on(dev->net);
2011 	else
2012 		netif_carrier_off(dev->net);
2013 
2014 	if (need_reset && link)
2015 		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
2016 	else
2017 		usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
2018 }
2019 EXPORT_SYMBOL(usbnet_link_change);
2020 
2021 /*-------------------------------------------------------------------------*/
2022 static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
2023 			     u16 value, u16 index, void *data, u16 size)
2024 {
2025 	void *buf = NULL;
2026 	int err = -ENOMEM;
2027 
2028 	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
2029 		   " value=0x%04x index=0x%04x size=%d\n",
2030 		   cmd, reqtype, value, index, size);
2031 
2032 	if (size) {
2033 		buf = kmalloc(size, GFP_NOIO);
2034 		if (!buf)
2035 			goto out;
2036 	}
2037 
2038 	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
2039 			      cmd, reqtype, value, index, buf, size,
2040 			      USB_CTRL_GET_TIMEOUT);
2041 	if (err > 0 && err <= size) {
2042 		if (data)
2043 			memcpy(data, buf, err);
2044 		else
2045 			netdev_dbg(dev->net,
2046 				   "Huh? Data requested but thrown away.\n");
2047 	}
2048 	kfree(buf);
2049 out:
2050 	return err;
2051 }
2052 
2053 static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
2054 			      u16 value, u16 index, const void *data,
2055 			      u16 size)
2056 {
2057 	void *buf = NULL;
2058 	int err = -ENOMEM;
2059 
2060 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
2061 		   " value=0x%04x index=0x%04x size=%d\n",
2062 		   cmd, reqtype, value, index, size);
2063 
2064 	if (data) {
2065 		buf = kmemdup(data, size, GFP_NOIO);
2066 		if (!buf)
2067 			goto out;
2068 	} else {
2069         if (size) {
2070             WARN_ON_ONCE(1);
2071             err = -EINVAL;
2072             goto out;
2073         }
2074     }
2075 
2076 	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
2077 			      cmd, reqtype, value, index, buf, size,
2078 			      USB_CTRL_SET_TIMEOUT);
2079 	kfree(buf);
2080 
2081 out:
2082 	return err;
2083 }
2084 
2085 /*
2086  * The function can't be called inside suspend/resume callback,
2087  * otherwise deadlock will be caused.
2088  */
2089 int usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
2090 		    u16 value, u16 index, void *data, u16 size)
2091 {
2092 	int ret;
2093 
2094 	if (usb_autopm_get_interface(dev->intf) < 0)
2095 		return -ENODEV;
2096 	ret = __usbnet_read_cmd(dev, cmd, reqtype, value, index,
2097 				data, size);
2098 	usb_autopm_put_interface(dev->intf);
2099 	return ret;
2100 }
2101 EXPORT_SYMBOL_GPL(usbnet_read_cmd);
2102 
2103 /*
2104  * The function can't be called inside suspend/resume callback,
2105  * otherwise deadlock will be caused.
2106  */
2107 int usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
2108 		     u16 value, u16 index, const void *data, u16 size)
2109 {
2110 	int ret;
2111 
2112 	if (usb_autopm_get_interface(dev->intf) < 0)
2113 		return -ENODEV;
2114 	ret = __usbnet_write_cmd(dev, cmd, reqtype, value, index,
2115 				 data, size);
2116 	usb_autopm_put_interface(dev->intf);
2117 	return ret;
2118 }
2119 EXPORT_SYMBOL_GPL(usbnet_write_cmd);
2120 
2121 /*
2122  * The function can be called inside suspend/resume callback safely
2123  * and should only be called by suspend/resume callback generally.
2124  */
2125 int usbnet_read_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
2126 			  u16 value, u16 index, void *data, u16 size)
2127 {
2128 	return __usbnet_read_cmd(dev, cmd, reqtype, value, index,
2129 				 data, size);
2130 }
2131 EXPORT_SYMBOL_GPL(usbnet_read_cmd_nopm);
2132 
2133 /*
2134  * The function can be called inside suspend/resume callback safely
2135  * and should only be called by suspend/resume callback generally.
2136  */
2137 int usbnet_write_cmd_nopm(struct usbnet *dev, u8 cmd, u8 reqtype,
2138 			  u16 value, u16 index, const void *data,
2139 			  u16 size)
2140 {
2141 	return __usbnet_write_cmd(dev, cmd, reqtype, value, index,
2142 				  data, size);
2143 }
2144 EXPORT_SYMBOL_GPL(usbnet_write_cmd_nopm);
2145 
2146 static void usbnet_async_cmd_cb(struct urb *urb)
2147 {
2148 	struct usb_ctrlrequest *req = (struct usb_ctrlrequest *)urb->context;
2149 	int status = urb->status;
2150 
2151 	if (status < 0)
2152 		dev_dbg(&urb->dev->dev, "%s failed with %d",
2153 			__func__, status);
2154 
2155 	kfree(req);
2156 	usb_free_urb(urb);
2157 }
2158 
2159 /*
2160  * The caller must make sure that device can't be put into suspend
2161  * state until the control URB completes.
2162  */
2163 int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
2164 			   u16 value, u16 index, const void *data, u16 size)
2165 {
2166 	struct usb_ctrlrequest *req;
2167 	struct urb *urb;
2168 	int err = -ENOMEM;
2169 	void *buf = NULL;
2170 
2171 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
2172 		   " value=0x%04x index=0x%04x size=%d\n",
2173 		   cmd, reqtype, value, index, size);
2174 
2175 	urb = usb_alloc_urb(0, GFP_ATOMIC);
2176 	if (!urb)
2177 		goto fail;
2178 
2179 	if (data) {
2180 		buf = kmemdup(data, size, GFP_ATOMIC);
2181 		if (!buf) {
2182 			netdev_err(dev->net, "Error allocating buffer"
2183 				   " in %s!\n", __func__);
2184 			goto fail_free_urb;
2185 		}
2186 	}
2187 
2188 	req = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
2189 	if (!req)
2190 		goto fail_free_buf;
2191 
2192 	req->bRequestType = reqtype;
2193 	req->bRequest = cmd;
2194 	req->wValue = cpu_to_le16(value);
2195 	req->wIndex = cpu_to_le16(index);
2196 	req->wLength = cpu_to_le16(size);
2197 
2198 	usb_fill_control_urb(urb, dev->udev,
2199 			     usb_sndctrlpipe(dev->udev, 0),
2200 			     (void *)req, buf, size,
2201 			     usbnet_async_cmd_cb, req);
2202 	urb->transfer_flags |= URB_FREE_BUFFER;
2203 
2204 	err = usb_submit_urb(urb, GFP_ATOMIC);
2205 	if (err < 0) {
2206 		netdev_err(dev->net, "Error submitting the control"
2207 			   " message: status=%d\n", err);
2208 		goto fail_free_all;
2209 	}
2210 	return 0;
2211 
2212 fail_free_all:
2213 	kfree(req);
2214 fail_free_buf:
2215 	kfree(buf);
2216 	/*
2217 	 * avoid a double free
2218 	 * needed because the flag can be set only
2219 	 * after filling the URB
2220 	 */
2221 	urb->transfer_flags = 0;
2222 fail_free_urb:
2223 	usb_free_urb(urb);
2224 fail:
2225 	return err;
2226 
2227 }
2228 EXPORT_SYMBOL_GPL(usbnet_write_cmd_async);
2229 /*-------------------------------------------------------------------------*/
2230 
2231 static int __init usbnet_init(void)
2232 {
2233 	/* Compiler should optimize this out. */
2234 	BUILD_BUG_ON(
2235 		sizeof_field(struct sk_buff, cb) < sizeof(struct skb_data));
2236 
2237 	return 0;
2238 }
2239 module_init(usbnet_init);
2240 
2241 static void __exit usbnet_exit(void)
2242 {
2243 }
2244 module_exit(usbnet_exit);
2245 
2246 MODULE_AUTHOR("David Brownell");
2247 MODULE_DESCRIPTION("USB network driver framework");
2248 MODULE_LICENSE("GPL");
2249