aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/net/sfc/rx.c
blob: 01f9432c31ef9f2c02ec3df3dce4159c2fda1bb4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
/****************************************************************************
 * Driver for Solarflare Solarstorm network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2005-2008 Solarflare Communications Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, incorporated herein by reference.
 */

#include <linux/socket.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <net/ip.h>
#include <net/checksum.h>
#include "net_driver.h"
#include "rx.h"
#include "efx.h"
#include "falcon.h"
#include "selftest.h"
#include "workarounds.h"

/* Number of RX descriptors pushed at once. */
#define EFX_RX_BATCH  8

/* Size of buffer allocated for skb header area. */
#define EFX_SKB_HEADERS  64u

/*
 * rx_alloc_method - RX buffer allocation method
 *
 * This driver supports two methods for allocating and using RX buffers:
 * each RX buffer may be backed by an skb or by an order-n page.
 *
 * When LRO is in use then the second method has a lower overhead,
 * since we don't have to allocate then free skbs on reassembled frames.
 *
 * Values:
 *   - RX_ALLOC_METHOD_AUTO = 0
 *   - RX_ALLOC_METHOD_SKB  = 1
 *   - RX_ALLOC_METHOD_PAGE = 2
 *
 * The heuristic for %RX_ALLOC_METHOD_AUTO is a simple hysteresis count
 * controlled by the parameters below.
 *
 *   - Since pushing and popping descriptors are separated by the rx_queue
 *     size, so the watermarks should be ~rxd_size.
 *   - The performance win by using page-based allocation for LRO is less
 *     than the performance hit of using page-based allocation of non-LRO,
 *     so the watermarks should reflect this.
 *
 * Per channel we maintain a single variable, updated by each channel:
 *
 *   rx_alloc_level += (lro_performed ? RX_ALLOC_FACTOR_LRO :
 *                      RX_ALLOC_FACTOR_SKB)
 * Per NAPI poll interval, we constrain rx_alloc_level to 0..MAX (which
 * limits the hysteresis), and update the allocation strategy:
 *
 *   rx_alloc_method = (rx_alloc_level > RX_ALLOC_LEVEL_LRO ?
 *                      RX_ALLOC_METHOD_PAGE : RX_ALLOC_METHOD_SKB)
 */
static int rx_alloc_method = RX_ALLOC_METHOD_PAGE;

#define RX_ALLOC_LEVEL_LRO 0x2000
#define RX_ALLOC_LEVEL_MAX 0x3000
#define RX_ALLOC_FACTOR_LRO 1
#define RX_ALLOC_FACTOR_SKB (-2)

/* This is the percentage fill level below which new RX descriptors
 * will be added to the RX descriptor ring.
 */
static unsigned int rx_refill_threshold = 90;

/* This is the percentage fill level to which an RX queue will be refilled
 * when the "RX refill threshold" is reached.
 */
static unsigned int rx_refill_limit = 95;

/*
 * RX maximum head room required.
 *
 * This must be at least 1 to prevent overflow and at least 2 to allow
 * pipelined receives.
 */
#define EFX_RXD_HEAD_ROOM 2

static inline unsigned int efx_rx_buf_offset(struct efx_rx_buffer *buf)
{
	/* Offset is always within one page, so we don't need to consider
	 * the page order.
	 */
	return (__force unsigned long) buf->data & (PAGE_SIZE - 1);
}
static inline unsigned int efx_rx_buf_size(struct efx_nic *efx)
{
	return PAGE_SIZE << efx->rx_buffer_order;
}


/**
 * efx_init_rx_buffer_skb - create new RX buffer using skb-based allocation
 *
 * @rx_queue:		Efx RX queue
 * @rx_buf:		RX buffer structure to populate
 *
 * This allocates memory for a new receive buffer, maps it for DMA,
 * and populates a struct efx_rx_buffer with the relevant
 * information.  Return a negative error code or 0 on success.
 */
static int efx_init_rx_buffer_skb(struct efx_rx_queue *rx_queue,
				  struct efx_rx_buffer *rx_buf)
{
	struct efx_nic *efx = rx_queue->efx;
	struct net_device *net_dev = efx->net_dev;
	int skb_len = efx->rx_buffer_len;

	rx_buf->skb = netdev_alloc_skb(net_dev, skb_len);
	if (unlikely(!rx_buf->skb))
		return -ENOMEM;

	/* Adjust the SKB for padding and checksum */
	skb_reserve(rx_buf->skb, NET_IP_ALIGN);
	rx_buf->len = skb_len - NET_IP_ALIGN;
	rx_buf->data = (char *)rx_buf->skb->data;
	rx_buf->skb->ip_summed = CHECKSUM_UNNECESSARY;

	rx_buf->dma_addr = pci_map_single(efx->pci_dev,
					  rx_buf->data, rx_buf->len,
					  PCI_DMA_FROMDEVICE);

	if (unlikely(pci_dma_mapping_error(efx->pci_dev, rx_buf->dma_addr))) {
		dev_kfree_skb_any(rx_buf->skb);
		rx_buf->skb = NULL;
		return -EIO;
	}

	return 0;
}

/**
 * efx_init_rx_buffer_page - create new RX buffer using page-based allocation
 *
 * @rx_queue:		Efx RX queue
 * @rx_buf:		RX buffer structure to populate
 *
 * This allocates memory for a new receive buffer, maps it for DMA,
 * and populates a struct efx_rx_buffer with the relevant
 * information.  Return a negative error code or 0 on success.
 */
static int efx_init_rx_buffer_page(struct efx_rx_queue *rx_queue,
				   struct efx_rx_buffer *rx_buf)
{
	struct efx_nic *efx = rx_queue->efx;
	int bytes, space, offset;

	bytes = efx->rx_buffer_len - EFX_PAGE_IP_ALIGN;

	/* If there is space left in the previously allocated page,
	 * then use it. Otherwise allocate a new one */
	rx_buf->page = rx_queue->buf_page;
	if (rx_buf->page == NULL) {
		dma_addr_t dma_addr;

		rx_buf->page = alloc_pages(__GFP_COLD | __GFP_COMP | GFP_ATOMIC,
					   efx->rx_buffer_order);
		if (unlikely(rx_buf->page == NULL))
			return -ENOMEM;

		dma_addr = pci_map_page(efx->pci_dev, rx_buf->page,
					0, efx_rx_buf_size(efx),
					PCI_DMA_FROMDEVICE);

		if (unlikely(pci_dma_mapping_error(efx->pci_dev, dma_addr))) {
			__free_pages(rx_buf->page, efx->rx_buffer_order);
			rx_buf->page = NULL;
			return -EIO;
		}

		rx_queue->buf_page = rx_buf->page;
		rx_queue->buf_dma_addr = dma_addr;
		rx_queue->buf_data = (page_address(rx_buf->page) +
				      EFX_PAGE_IP_ALIGN);
	}

	rx_buf->len = bytes;
	rx_buf->data = rx_queue->buf_data;
	offset = efx_rx_buf_offset(rx_buf);
	rx_buf->dma_addr = rx_queue->buf_dma_addr + offset;

	/* Try to pack multiple buffers per page */
	if (efx->rx_buffer_order == 0) {
		/* The next buffer starts on the next 512 byte boundary */
		rx_queue->buf_data += ((bytes + 0x1ff) & ~0x1ff);
		offset += ((bytes + 0x1ff) & ~0x1ff);

		space = efx_rx_buf_size(efx) - offset;
		if (space >= bytes) {
			/* Refs dropped on kernel releasing each skb */
			get_page(rx_queue->buf_page);
			goto out;
		}
	}

	/* This is the final RX buffer for this page, so mark it for
	 * unmapping */
	rx_queue->buf_page = NULL;
	rx_buf->unmap_addr = rx_queue->buf_dma_addr;

 out:
	return 0;
}

/* This allocates memory for a new receive buffer, maps it for DMA,
 * and populates a struct efx_rx_buffer with the relevant
 * information.
 */
static int efx_init_rx_buffer(struct efx_rx_queue *rx_queue,
			      struct efx_rx_buffer *new_rx_buf)
{
	int rc = 0;

	if (rx_queue->channel->rx_alloc_push_pages) {
		new_rx_buf->skb = NULL;
		rc = efx_init_rx_buffer_page(rx_queue, new_rx_buf);
		rx_queue->alloc_page_count++;
	} else {
		new_rx_buf->page = NULL;
		rc = efx_init_rx_buffer_skb(rx_queue, new_rx_buf);
		rx_queue->alloc_skb_count++;
	}

	if (unlikely(rc < 0))
		EFX_LOG_RL(rx_queue->efx, "%s RXQ[%d] =%d\n", __func__,
			   rx_queue->queue, rc);
	return rc;
}

static void efx_unmap_rx_buffer(struct efx_nic *efx,
				struct efx_rx_buffer *rx_buf)
{
	if (rx_buf->page) {
		EFX_BUG_ON_PARANOID(rx_buf->skb);
		if (rx_buf->unmap_addr) {
			pci_unmap_page(efx->pci_dev, rx_buf->unmap_addr,
				       efx_rx_buf_size(efx),
				       PCI_DMA_FROMDEVICE);
			rx_buf->unmap_addr = 0;
		}
	} else if (likely(rx_buf->skb)) {
		pci_unmap_single(efx->pci_dev, rx_buf->dma_addr,
				 rx_buf->len, PCI_DMA_FROMDEVICE);
	}
}

static void efx_free_rx_buffer(struct efx_nic *efx,
			       struct efx_rx_buffer *rx_buf)
{
	if (rx_buf->page) {
		__free_pages(rx_buf->page, efx->rx_buffer_order);
		rx_buf->page = NULL;
	} else if (likely(rx_buf->skb)) {
		dev_kfree_skb_any(rx_buf->skb);
		rx_buf->skb = NULL;
	}
}

static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue,
			       struct efx_rx_buffer *rx_buf)
{
	efx_unmap_rx_buffer(rx_queue->efx, rx_buf);
	efx_free_rx_buffer(rx_queue->efx, rx_buf);
}

/**
 * efx_fast_push_rx_descriptors - push new RX descriptors quickly
 * @rx_queue:		RX descriptor queue
 * @retry:              Recheck the fill level
 * This will aim to fill the RX descriptor queue up to
 * @rx_queue->@fast_fill_limit. If there is insufficient atomic
 * memory to do so, the caller should retry.
 */
static int __efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue,
					  int retry)
{
	struct efx_rx_buffer *rx_buf;
	unsigned fill_level, index;
	int i, space, rc = 0;

	/* Calculate current fill level.  Do this outside the lock,
	 * because most of the time we'll end up not wanting to do the
	 * fill anyway.
	 */
	fill_level = (rx_queue->added_count - rx_queue->removed_count);
	EFX_BUG_ON_PARANOID(fill_level >
			    rx_queue->efx->type->rxd_ring_mask + 1);

	/* Don't fill if we don't need to */
	if (fill_level >= rx_queue->fast_fill_trigger)
		return 0;

	/* Record minimum fill level */
	if (unlikely(fill_level < rx_queue->min_fill)) {
		if (fill_level)
			rx_queue->min_fill = fill_level;
	}

	/* Acquire RX add lock.  If this lock is contended, then a fast
	 * fill must already be in progress (e.g. in the refill
	 * tasklet), so we don't need to do anything
	 */
	if (!spin_trylock_bh(&rx_queue->add_lock))
		return -1;

 retry:
	/* Recalculate current fill level now that we have the lock */
	fill_level = (rx_queue->added_count - rx_queue->removed_count);
	EFX_BUG_ON_PARANOID(fill_level >
			    rx_queue->efx->type->rxd_ring_mask + 1);
	space = rx_queue->fast_fill_limit - fill_level;
	if (space < EFX_RX_BATCH)
		goto out_unlock;

	EFX_TRACE(rx_queue->efx, "RX queue %d fast-filling descriptor ring from"
		  " level %d to level %d using %s allocation\n",
		  rx_queue->queue, fill_level, rx_queue->fast_fill_limit,
		  rx_queue->channel->rx_alloc_push_pages ? "page" : "skb");

	do {
		for (i = 0; i < EFX_RX_BATCH; ++i) {
			index = (rx_queue->added_count &
				 rx_queue->efx->type->rxd_ring_mask);
			rx_buf = efx_rx_buffer(rx_queue, index);
			rc = efx_init_rx_buffer(rx_queue, rx_buf);
			if (unlikely(rc))
				goto out;
			++rx_queue->added_count;
		}
	} while ((space -= EFX_RX_BATCH) >= EFX_RX_BATCH);

	EFX_TRACE(rx_queue->efx, "RX queue %d fast-filled descriptor ring "
		  "to level %d\n", rx_queue->queue,
		  rx_queue->added_count - rx_queue->removed_count);

 out:
	/* Send write pointer to card. */
	falcon_notify_rx_desc(rx_queue);

	/* If the fast fill is running inside from the refill tasklet, then
	 * for SMP systems it may be running on a different CPU to
	 * RX event processing, which means that the fill level may now be
	 * out of date. */
	if (unlikely(retry && (rc == 0)))
		goto retry;

 out_unlock:
	spin_unlock_bh(&rx_queue->add_lock);

	return rc;
}

/**
 * efx_fast_push_rx_descriptors - push new RX descriptors quickly
 * @rx_queue:		RX descriptor queue
 *
 * This will aim to fill the RX descriptor queue up to
 * @rx_queue->@fast_fill_limit.  If there is insufficient memory to do so,
 * it will schedule a work item to immediately continue the fast fill
 */
void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
{
	int rc;

	rc = __efx_fast_push_rx_descriptors(rx_queue, 0);
	if (unlikely(rc)) {
		/* Schedule the work item to run immediately. The hope is
		 * that work is immediately pending to free some memory
		 * (e.g. an RX event or TX completion)
		 */
		efx_schedule_slow_fill(rx_queue, 0);
	}
}

void efx_rx_work(struct work_struct *data)
{
	struct efx_rx_queue *rx_queue;
	int rc;

	rx_queue = container_of(data, struct efx_rx_queue, work.work);

	if (unlikely(!rx_queue->channel->enabled))
		return;

	EFX_TRACE(rx_queue->efx, "RX queue %d worker thread executing on CPU "
		  "%d\n", rx_queue->queue, raw_smp_processor_id());

	++rx_queue->slow_fill_count;
	/* Push new RX descriptors, allowing at least 1 jiffy for
	 * the kernel to free some more memory. */
	rc = __efx_fast_push_rx_descriptors(rx_queue, 1);
	if (rc)
		efx_schedule_slow_fill(rx_queue, 1);
}

static void efx_rx_packet__check_len(struct efx_rx_queue *rx_queue,
				     struct efx_rx_buffer *rx_buf,
				     int len, bool *discard,
				     bool *leak_packet)
{
	struct efx_nic *efx = rx_queue->efx;
	unsigned max_len = rx_buf->len - efx->type->rx_buffer_padding;

	if (likely(len <= max_len))
		return;

	/* The packet must be discarded, but this is only a fatal error
	 * if the caller indicated it was
	 */
	*discard = true;

	if ((len > rx_buf->len) && EFX_WORKAROUND_8071(efx)) {
		EFX_ERR_RL(efx, " RX queue %d seriously overlength "
			   "RX event (0x%x > 0x%x+0x%x). Leaking\n",
			   rx_queue->queue, len, max_len,
			   efx->type->rx_buffer_padding);
		/* If this buffer was skb-allocated, then the meta
		 * data at the end of the skb will be trashed. So
		 * we have no choice but to leak the fragment.
		 */
		*leak_packet = (rx_buf->skb != NULL);
		efx_schedule_reset(efx, RESET_TYPE_RX_RECOVERY);
	} else {
		EFX_ERR_RL(efx, " RX queue %d overlength RX event "
			   "(0x%x > 0x%x)\n", rx_queue->queue, len, max_len);
	}

	rx_queue->channel->n_rx_overlength++;
}

/* Pass a received packet up through the generic LRO stack
 *
 * Handles driverlink veto, and passes the fragment up via
 * the appropriate LRO method
 */
static void efx_rx_packet_lro(struct efx_channel *channel,
			      struct efx_rx_buffer *rx_buf)
{
	struct napi_struct *napi = &channel->napi_str;

	/* Pass the skb/page into the LRO engine */
	if (rx_buf->page) {
		struct sk_buff *skb = napi_get_frags(napi);

		if (!skb) {
			put_page(rx_buf->page);
			goto out;
		}

		skb_shinfo(skb)->frags[0].page = rx_buf->page;
		skb_shinfo(skb)->frags[0].page_offset =
			efx_rx_buf_offset(rx_buf);
		skb_shinfo(skb)->frags[0].size = rx_buf->len;
		skb_shinfo(skb)->nr_frags = 1;

		skb->len = rx_buf->len;
		skb->data_len = rx_buf->len;
		skb->truesize += rx_buf->len;
		skb->ip_summed = CHECKSUM_UNNECESSARY;

		napi_gro_frags(napi);

out:
		EFX_BUG_ON_PARANOID(rx_buf->skb);
		rx_buf->page = NULL;
	} else {
		EFX_BUG_ON_PARANOID(!rx_buf->skb);

		napi_gro_receive(napi, rx_buf->skb);
		rx_buf->skb = NULL;
	}
}

void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
		   unsigned int len, bool checksummed, bool discard)
{
	struct efx_nic *efx = rx_queue->efx;
	struct efx_rx_buffer *rx_buf;
	bool leak_packet = false;

	rx_buf = efx_rx_buffer(rx_queue, index);
	EFX_BUG_ON_PARANOID(!rx_buf->data);
	EFX_BUG_ON_PARANOID(rx_buf->skb && rx_buf->page);
	EFX_BUG_ON_PARANOID(!(rx_buf->skb || rx_buf->page));

	/* This allows the refill path to post another buffer.
	 * EFX_RXD_HEAD_ROOM ensures that the slot we are using
	 * isn't overwritten yet.
	 */
	rx_queue->removed_count++;

	/* Validate the length encoded in the event vs the descriptor pushed */
	efx_rx_packet__check_len(rx_queue, rx_buf, len,
				 &discard, &leak_packet);

	EFX_TRACE(efx, "RX queue %d received id %x at %llx+%x %s%s\n",
		  rx_queue->queue, index,
		  (unsigned long long)rx_buf->dma_addr, len,
		  (checksummed ? " [SUMMED]" : ""),
		  (discard ? " [DISCARD]" : ""));

	/* Discard packet, if instructed to do so */
	if (unlikely(discard)) {
		if (unlikely(leak_packet))
			rx_queue->channel->n_skbuff_leaks++;
		else
			/* We haven't called efx_unmap_rx_buffer yet,
			 * so fini the entire rx_buffer here */
			efx_fini_rx_buffer(rx_queue, rx_buf);
		return;
	}

	/* Release card resources - assumes all RX buffers consumed in-order
	 * per RX queue
	 */
	efx_unmap_rx_buffer(efx, rx_buf);

	/* Prefetch nice and early so data will (hopefully) be in cache by
	 * the time we look at it.
	 */
	prefetch(rx_buf->data);

	/* Pipeline receives so that we give time for packet headers to be
	 * prefetched into cache.
	 */
	rx_buf->len = len;
	if (rx_queue->channel->rx_pkt)
		__efx_rx_packet(rx_queue->channel,
				rx_queue->channel->rx_pkt,
				rx_queue->channel->rx_pkt_csummed);
	rx_queue->channel->rx_pkt = rx_buf;
	rx_queue->channel->rx_pkt_csummed = checksummed;
}

/* Handle a received packet.  Second half: Touches packet payload. */
void __efx_rx_packet(struct efx_channel *channel,
		     struct efx_rx_buffer *rx_buf, bool checksummed)
{
	struct efx_nic *efx = channel->efx;
	struct sk_buff *skb;

	/* If we're in loopback test, then pass the packet directly to the
	 * loopback layer, and free the rx_buf here
	 */
	if (unlikely(efx->loopback_selftest)) {
		efx_loopback_rx_packet(efx, rx_buf->data, rx_buf->len);
		efx_free_rx_buffer(efx, rx_buf);
		goto done;
	}

	if (rx_buf->skb) {
		prefetch(skb_shinfo(rx_buf->skb));

		skb_put(rx_buf->skb, rx_buf->len);

		/* Move past the ethernet header. rx_buf->data still points
		 * at the ethernet header */
		rx_buf->skb->protocol = eth_type_trans(rx_buf->skb,
						       efx->net_dev);
	}

	if (likely(checksummed || rx_buf->page)) {
		efx_rx_packet_lro(channel, rx_buf);
		goto done;
	}

	/* We now own the SKB */
	skb = rx_buf->skb;
	rx_buf->skb = NULL;

	EFX_BUG_ON_PARANOID(rx_buf->page);
	EFX_BUG_ON_PARANOID(rx_buf->skb);
	EFX_BUG_ON_PARANOID(!skb);

	/* Set the SKB flags */
	skb->ip_summed = CHECKSUM_NONE;

	skb_record_rx_queue(skb, channel->channel);

	/* Pass the packet up */
	netif_receive_skb(skb);

	/* Update allocation strategy method */
	channel->rx_alloc_level += RX_ALLOC_FACTOR_SKB;

done:
	;
}

void efx_rx_strategy(struct efx_channel *channel)
{
	enum efx_rx_alloc_method method = rx_alloc_method;

	/* Only makes sense to use page based allocation if LRO is enabled */
	if (!(channel->efx->net_dev->features & NETIF_F_GRO)) {
		method = RX_ALLOC_METHOD_SKB;
	} else if (method == RX_ALLOC_METHOD_AUTO) {
		/* Constrain the rx_alloc_level */
		if (channel->rx_alloc_level < 0)
			channel->rx_alloc_level = 0;
		else if (channel->rx_alloc_level > RX_ALLOC_LEVEL_MAX)
			channel->rx_alloc_level = RX_ALLOC_LEVEL_MAX;

		/* Decide on the allocation method */
		method = ((channel->rx_alloc_level > RX_ALLOC_LEVEL_LRO) ?
			  RX_ALLOC_METHOD_PAGE : RX_ALLOC_METHOD_SKB);
	}

	/* Push the option */
	channel->rx_alloc_push_pages = (method == RX_ALLOC_METHOD_PAGE);
}

int efx_probe_rx_queue(struct efx_rx_queue *rx_queue)
{
	struct efx_nic *efx = rx_queue->efx;
	unsigned int rxq_size;
	int rc;

	EFX_LOG(efx, "creating RX queue %d\n", rx_queue->queue);

	/* Allocate RX buffers */
	rxq_size = (efx->type->rxd_ring_mask + 1) * sizeof(*rx_queue->buffer);
	rx_queue->buffer = kzalloc(rxq_size, GFP_KERNEL);
	if (!rx_queue->buffer)
		return -ENOMEM;

	rc = falcon_probe_rx(rx_queue);
	if (rc) {
		kfree(rx_queue->buffer);
		rx_queue->buffer = NULL;
	}
	return rc;
}

void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
{
	struct efx_nic *efx = rx_queue->efx;
	unsigned int max_fill, trigger, limit;

	EFX_LOG(rx_queue->efx, "initialising RX queue %d\n", rx_queue->queue);

	/* Initialise ptr fields */
	rx_queue->added_count = 0;
	rx_queue->notified_count = 0;
	rx_queue->removed_count = 0;
	rx_queue->min_fill = -1U;
	rx_queue->min_overfill = -1U;

	/* Initialise limit fields */
	max_fill = efx->type->rxd_ring_mask + 1 - EFX_RXD_HEAD_ROOM;
	trigger = max_fill * min(rx_refill_threshold, 100U) / 100U;
	limit = max_fill * min(rx_refill_limit, 100U) / 100U;

	rx_queue->max_fill = max_fill;
	rx_queue->fast_fill_trigger = trigger;
	rx_queue->fast_fill_limit = limit;

	/* Set up RX descriptor ring */
	falcon_init_rx(rx_queue);
}

void efx_fini_rx_queue(struct efx_rx_queue *rx_queue)
{
	int i;
	struct efx_rx_buffer *rx_buf;

	EFX_LOG(rx_queue->efx, "shutting down RX queue %d\n", rx_queue->queue);

	falcon_fini_rx(rx_queue);

	/* Release RX buffers NB start at index 0 not current HW ptr */
	if (rx_queue->buffer) {
		for (i = 0; i <= rx_queue->efx->type->rxd_ring_mask; i++) {
			rx_buf = efx_rx_buffer(rx_queue, i);
			efx_fini_rx_buffer(rx_queue, rx_buf);
		}
	}

	/* For a page that is part-way through splitting into RX buffers */
	if (rx_queue->buf_page != NULL) {
		pci_unmap_page(rx_queue->efx->pci_dev, rx_queue->buf_dma_addr,
			       efx_rx_buf_size(rx_queue->efx),
			       PCI_DMA_FROMDEVICE);
		__free_pages(rx_queue->buf_page,
			     rx_queue->efx->rx_buffer_order);
		rx_queue->buf_page = NULL;
	}
}

void efx_remove_rx_queue(struct efx_rx_queue *rx_queue)
{
	EFX_LOG(rx_queue->efx, "destroying RX queue %d\n", rx_queue->queue);

	falcon_remove_rx(rx_queue);

	kfree(rx_queue->buffer);
	rx_queue->buffer = NULL;
}


module_param(rx_alloc_method, int, 0644);
MODULE_PARM_DESC(rx_alloc_method, "Allocation method used for RX buffers");

module_param(rx_refill_threshold, uint, 0444);
MODULE_PARM_DESC(rx_refill_threshold,
		 "RX descriptor ring fast/slow fill threshold (%)");