Free Electrons

Embedded Linux Experts

   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
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
/* A network driver using virtio.
 *
 * Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
//#define DEBUG
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_net.h>
#include <linux/scatterlist.h>
#include <linux/if_vlan.h>
#include <linux/slab.h>

static int napi_weight = 128;
module_param(napi_weight, int, 0444);

static bool csum = true, gso = true;
module_param(csum, bool, 0444);
module_param(gso, bool, 0444);

/* FIXME: MTU in config. */
#define MAX_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
#define GOOD_COPY_LEN	128

#define VIRTNET_SEND_COMMAND_SG_MAX    2
#define VIRTNET_DRIVER_VERSION "1.0.0"

struct virtnet_stats {
	struct u64_stats_sync syncp;
	u64 tx_bytes;
	u64 tx_packets;

	u64 rx_bytes;
	u64 rx_packets;
};

struct virtnet_info {
	struct virtio_device *vdev;
	struct virtqueue *rvq, *svq, *cvq;
	struct net_device *dev;
	struct napi_struct napi;
	unsigned int status;

	/* Number of input buffers, and max we've ever had. */
	unsigned int num, max;

	/* I like... big packets and I cannot lie! */
	bool big_packets;

	/* Host will merge rx buffers for big packets (shake it! shake it!) */
	bool mergeable_rx_bufs;

	/* Active statistics */
	struct virtnet_stats __percpu *stats;

	/* Work struct for refilling if we run low on memory. */
	struct delayed_work refill;

	/* Chain pages by the private ptr. */
	struct page *pages;

	/* fragments + linear part + virtio header */
	struct scatterlist rx_sg[MAX_SKB_FRAGS + 2];
	struct scatterlist tx_sg[MAX_SKB_FRAGS + 2];
};

struct skb_vnet_hdr {
	union {
		struct virtio_net_hdr hdr;
		struct virtio_net_hdr_mrg_rxbuf mhdr;
	};
	unsigned int num_sg;
};

struct padded_vnet_hdr {
	struct virtio_net_hdr hdr;
	/*
	 * virtio_net_hdr should be in a separated sg buffer because of a
	 * QEMU bug, and data sg buffer shares same page with this header sg.
	 * This padding makes next sg 16 byte aligned after virtio_net_hdr.
	 */
	char padding[6];
};

static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb)
{
	return (struct skb_vnet_hdr *)skb->cb;
}

/*
 * private is used to chain pages for big packets, put the whole
 * most recent used list in the beginning for reuse
 */
static void give_pages(struct virtnet_info *vi, struct page *page)
{
	struct page *end;

	/* Find end of list, sew whole thing into vi->pages. */
	for (end = page; end->private; end = (struct page *)end->private);
	end->private = (unsigned long)vi->pages;
	vi->pages = page;
}

static struct page *get_a_page(struct virtnet_info *vi, gfp_t gfp_mask)
{
	struct page *p = vi->pages;

	if (p) {
		vi->pages = (struct page *)p->private;
		/* clear private here, it is used to chain pages */
		p->private = 0;
	} else
		p = alloc_page(gfp_mask);
	return p;
}

static void skb_xmit_done(struct virtqueue *svq)
{
	struct virtnet_info *vi = svq->vdev->priv;

	/* Suppress further interrupts. */
	virtqueue_disable_cb(svq);

	/* We were probably waiting for more output buffers. */
	netif_wake_queue(vi->dev);
}

static void set_skb_frag(struct sk_buff *skb, struct page *page,
			 unsigned int offset, unsigned int *len)
{
	int size = min((unsigned)PAGE_SIZE - offset, *len);
	int i = skb_shinfo(skb)->nr_frags;

	__skb_fill_page_desc(skb, i, page, offset, size);

	skb->data_len += size;
	skb->len += size;
	skb->truesize += PAGE_SIZE;
	skb_shinfo(skb)->nr_frags++;
	*len -= size;
}

/* Called from bottom half context */
static struct sk_buff *page_to_skb(struct virtnet_info *vi,
				   struct page *page, unsigned int len)
{
	struct sk_buff *skb;
	struct skb_vnet_hdr *hdr;
	unsigned int copy, hdr_len, offset;
	char *p;

	p = page_address(page);

	/* copy small packet so we can reuse these pages for small data */
	skb = netdev_alloc_skb_ip_align(vi->dev, GOOD_COPY_LEN);
	if (unlikely(!skb))
		return NULL;

	hdr = skb_vnet_hdr(skb);

	if (vi->mergeable_rx_bufs) {
		hdr_len = sizeof hdr->mhdr;
		offset = hdr_len;
	} else {
		hdr_len = sizeof hdr->hdr;
		offset = sizeof(struct padded_vnet_hdr);
	}

	memcpy(hdr, p, hdr_len);

	len -= hdr_len;
	p += offset;

	copy = len;
	if (copy > skb_tailroom(skb))
		copy = skb_tailroom(skb);
	memcpy(skb_put(skb, copy), p, copy);

	len -= copy;
	offset += copy;

	/*
	 * Verify that we can indeed put this data into a skb.
	 * This is here to handle cases when the device erroneously
	 * tries to receive more than is possible. This is usually
	 * the case of a broken device.
	 */
	if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) {
		if (net_ratelimit())
			pr_debug("%s: too much data\n", skb->dev->name);
		dev_kfree_skb(skb);
		return NULL;
	}

	while (len) {
		set_skb_frag(skb, page, offset, &len);
		page = (struct page *)page->private;
		offset = 0;
	}

	if (page)
		give_pages(vi, page);

	return skb;
}

static int receive_mergeable(struct virtnet_info *vi, struct sk_buff *skb)
{
	struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);
	struct page *page;
	int num_buf, i, len;

	num_buf = hdr->mhdr.num_buffers;
	while (--num_buf) {
		i = skb_shinfo(skb)->nr_frags;
		if (i >= MAX_SKB_FRAGS) {
			pr_debug("%s: packet too long\n", skb->dev->name);
			skb->dev->stats.rx_length_errors++;
			return -EINVAL;
		}
		page = virtqueue_get_buf(vi->rvq, &len);
		if (!page) {
			pr_debug("%s: rx error: %d buffers missing\n",
				 skb->dev->name, hdr->mhdr.num_buffers);
			skb->dev->stats.rx_length_errors++;
			return -EINVAL;
		}

		if (len > PAGE_SIZE)
			len = PAGE_SIZE;

		set_skb_frag(skb, page, 0, &len);

		--vi->num;
	}
	return 0;
}

static void receive_buf(struct net_device *dev, void *buf, unsigned int len)
{
	struct virtnet_info *vi = netdev_priv(dev);
	struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
	struct sk_buff *skb;
	struct page *page;
	struct skb_vnet_hdr *hdr;

	if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
		pr_debug("%s: short packet %i\n", dev->name, len);
		dev->stats.rx_length_errors++;
		if (vi->mergeable_rx_bufs || vi->big_packets)
			give_pages(vi, buf);
		else
			dev_kfree_skb(buf);
		return;
	}

	if (!vi->mergeable_rx_bufs && !vi->big_packets) {
		skb = buf;
		len -= sizeof(struct virtio_net_hdr);
		skb_trim(skb, len);
	} else {
		page = buf;
		skb = page_to_skb(vi, page, len);
		if (unlikely(!skb)) {
			dev->stats.rx_dropped++;
			give_pages(vi, page);
			return;
		}
		if (vi->mergeable_rx_bufs)
			if (receive_mergeable(vi, skb)) {
				dev_kfree_skb(skb);
				return;
			}
	}

	hdr = skb_vnet_hdr(skb);

	u64_stats_update_begin(&stats->syncp);
	stats->rx_bytes += skb->len;
	stats->rx_packets++;
	u64_stats_update_end(&stats->syncp);

	if (hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
		pr_debug("Needs csum!\n");
		if (!skb_partial_csum_set(skb,
					  hdr->hdr.csum_start,
					  hdr->hdr.csum_offset))
			goto frame_err;
	} else if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) {
		skb->ip_summed = CHECKSUM_UNNECESSARY;
	}

	skb->protocol = eth_type_trans(skb, dev);
	pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
		 ntohs(skb->protocol), skb->len, skb->pkt_type);

	if (hdr->hdr.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		pr_debug("GSO!\n");
		switch (hdr->hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
		case VIRTIO_NET_HDR_GSO_TCPV4:
			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
			break;
		case VIRTIO_NET_HDR_GSO_UDP:
			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
			break;
		case VIRTIO_NET_HDR_GSO_TCPV6:
			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
			break;
		default:
			if (net_ratelimit())
				printk(KERN_WARNING "%s: bad gso type %u.\n",
				       dev->name, hdr->hdr.gso_type);
			goto frame_err;
		}

		if (hdr->hdr.gso_type & VIRTIO_NET_HDR_GSO_ECN)
			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;

		skb_shinfo(skb)->gso_size = hdr->hdr.gso_size;
		if (skb_shinfo(skb)->gso_size == 0) {
			if (net_ratelimit())
				printk(KERN_WARNING "%s: zero gso size.\n",
				       dev->name);
			goto frame_err;
		}

		/* Header must be checked, and gso_segs computed. */
		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
		skb_shinfo(skb)->gso_segs = 0;
	}

	netif_receive_skb(skb);
	return;

frame_err:
	dev->stats.rx_frame_errors++;
	dev_kfree_skb(skb);
}

static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp)
{
	struct sk_buff *skb;
	struct skb_vnet_hdr *hdr;
	int err;

	skb = __netdev_alloc_skb_ip_align(vi->dev, MAX_PACKET_LEN, gfp);
	if (unlikely(!skb))
		return -ENOMEM;

	skb_put(skb, MAX_PACKET_LEN);

	hdr = skb_vnet_hdr(skb);
	sg_set_buf(vi->rx_sg, &hdr->hdr, sizeof hdr->hdr);

	skb_to_sgvec(skb, vi->rx_sg + 1, 0, skb->len);

	err = virtqueue_add_buf(vi->rvq, vi->rx_sg, 0, 2, skb, gfp);
	if (err < 0)
		dev_kfree_skb(skb);

	return err;
}

static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp)
{
	struct page *first, *list = NULL;
	char *p;
	int i, err, offset;

	/* page in vi->rx_sg[MAX_SKB_FRAGS + 1] is list tail */
	for (i = MAX_SKB_FRAGS + 1; i > 1; --i) {
		first = get_a_page(vi, gfp);
		if (!first) {
			if (list)
				give_pages(vi, list);
			return -ENOMEM;
		}
		sg_set_buf(&vi->rx_sg[i], page_address(first), PAGE_SIZE);

		/* chain new page in list head to match sg */
		first->private = (unsigned long)list;
		list = first;
	}

	first = get_a_page(vi, gfp);
	if (!first) {
		give_pages(vi, list);
		return -ENOMEM;
	}
	p = page_address(first);

	/* vi->rx_sg[0], vi->rx_sg[1] share the same page */
	/* a separated vi->rx_sg[0] for virtio_net_hdr only due to QEMU bug */
	sg_set_buf(&vi->rx_sg[0], p, sizeof(struct virtio_net_hdr));

	/* vi->rx_sg[1] for data packet, from offset */
	offset = sizeof(struct padded_vnet_hdr);
	sg_set_buf(&vi->rx_sg[1], p + offset, PAGE_SIZE - offset);

	/* chain first in list head */
	first->private = (unsigned long)list;
	err = virtqueue_add_buf(vi->rvq, vi->rx_sg, 0, MAX_SKB_FRAGS + 2,
				first, gfp);
	if (err < 0)
		give_pages(vi, first);

	return err;
}

static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp)
{
	struct page *page;
	int err;

	page = get_a_page(vi, gfp);
	if (!page)
		return -ENOMEM;

	sg_init_one(vi->rx_sg, page_address(page), PAGE_SIZE);

	err = virtqueue_add_buf(vi->rvq, vi->rx_sg, 0, 1, page, gfp);
	if (err < 0)
		give_pages(vi, page);

	return err;
}

/*
 * Returns false if we couldn't fill entirely (OOM).
 *
 * Normally run in the receive path, but can also be run from ndo_open
 * before we're receiving packets, or from refill_work which is
 * careful to disable receiving (using napi_disable).
 */
static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp)
{
	int err;
	bool oom;

	do {
		if (vi->mergeable_rx_bufs)
			err = add_recvbuf_mergeable(vi, gfp);
		else if (vi->big_packets)
			err = add_recvbuf_big(vi, gfp);
		else
			err = add_recvbuf_small(vi, gfp);

		oom = err == -ENOMEM;
		if (err < 0)
			break;
		++vi->num;
	} while (err > 0);
	if (unlikely(vi->num > vi->max))
		vi->max = vi->num;
	virtqueue_kick(vi->rvq);
	return !oom;
}

static void skb_recv_done(struct virtqueue *rvq)
{
	struct virtnet_info *vi = rvq->vdev->priv;
	/* Schedule NAPI, Suppress further interrupts if successful. */
	if (napi_schedule_prep(&vi->napi)) {
		virtqueue_disable_cb(rvq);
		__napi_schedule(&vi->napi);
	}
}

static void virtnet_napi_enable(struct virtnet_info *vi)
{
	napi_enable(&vi->napi);

	/* If all buffers were filled by other side before we napi_enabled, we
	 * won't get another interrupt, so process any outstanding packets
	 * now.  virtnet_poll wants re-enable the queue, so we disable here.
	 * We synchronize against interrupts via NAPI_STATE_SCHED */
	if (napi_schedule_prep(&vi->napi)) {
		virtqueue_disable_cb(vi->rvq);
		local_bh_disable();
		__napi_schedule(&vi->napi);
		local_bh_enable();
	}
}

static void refill_work(struct work_struct *work)
{
	struct virtnet_info *vi;
	bool still_empty;

	vi = container_of(work, struct virtnet_info, refill.work);
	napi_disable(&vi->napi);
	still_empty = !try_fill_recv(vi, GFP_KERNEL);
	virtnet_napi_enable(vi);

	/* In theory, this can happen: if we don't get any buffers in
	 * we will *never* try to fill again. */
	if (still_empty)
		queue_delayed_work(system_nrt_wq, &vi->refill, HZ/2);
}

static int virtnet_poll(struct napi_struct *napi, int budget)
{
	struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
	void *buf;
	unsigned int len, received = 0;

again:
	while (received < budget &&
	       (buf = virtqueue_get_buf(vi->rvq, &len)) != NULL) {
		receive_buf(vi->dev, buf, len);
		--vi->num;
		received++;
	}

	if (vi->num < vi->max / 2) {
		if (!try_fill_recv(vi, GFP_ATOMIC))
			queue_delayed_work(system_nrt_wq, &vi->refill, 0);
	}

	/* Out of packets? */
	if (received < budget) {
		napi_complete(napi);
		if (unlikely(!virtqueue_enable_cb(vi->rvq)) &&
		    napi_schedule_prep(napi)) {
			virtqueue_disable_cb(vi->rvq);
			__napi_schedule(napi);
			goto again;
		}
	}

	return received;
}

static unsigned int free_old_xmit_skbs(struct virtnet_info *vi)
{
	struct sk_buff *skb;
	unsigned int len, tot_sgs = 0;
	struct virtnet_stats *stats = this_cpu_ptr(vi->stats);

	while ((skb = virtqueue_get_buf(vi->svq, &len)) != NULL) {
		pr_debug("Sent skb %p\n", skb);

		u64_stats_update_begin(&stats->syncp);
		stats->tx_bytes += skb->len;
		stats->tx_packets++;
		u64_stats_update_end(&stats->syncp);

		tot_sgs += skb_vnet_hdr(skb)->num_sg;
		dev_kfree_skb_any(skb);
	}
	return tot_sgs;
}

static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
{
	struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);
	const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;

	pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		hdr->hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
		hdr->hdr.csum_start = skb_checksum_start_offset(skb);
		hdr->hdr.csum_offset = skb->csum_offset;
	} else {
		hdr->hdr.flags = 0;
		hdr->hdr.csum_offset = hdr->hdr.csum_start = 0;
	}

	if (skb_is_gso(skb)) {
		hdr->hdr.hdr_len = skb_headlen(skb);
		hdr->hdr.gso_size = skb_shinfo(skb)->gso_size;
		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
			hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
			hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
		else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
			hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_UDP;
		else
			BUG();
		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
			hdr->hdr.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
	} else {
		hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;
		hdr->hdr.gso_size = hdr->hdr.hdr_len = 0;
	}

	hdr->mhdr.num_buffers = 0;

	/* Encode metadata header at front. */
	if (vi->mergeable_rx_bufs)
		sg_set_buf(vi->tx_sg, &hdr->mhdr, sizeof hdr->mhdr);
	else
		sg_set_buf(vi->tx_sg, &hdr->hdr, sizeof hdr->hdr);

	hdr->num_sg = skb_to_sgvec(skb, vi->tx_sg + 1, 0, skb->len) + 1;
	return virtqueue_add_buf(vi->svq, vi->tx_sg, hdr->num_sg,
				 0, skb, GFP_ATOMIC);
}

static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct virtnet_info *vi = netdev_priv(dev);
	int capacity;

	/* Free up any pending old buffers before queueing new ones. */
	free_old_xmit_skbs(vi);

	/* Try to transmit */
	capacity = xmit_skb(vi, skb);

	/* This can happen with OOM and indirect buffers. */
	if (unlikely(capacity < 0)) {
		if (likely(capacity == -ENOMEM)) {
			if (net_ratelimit())
				dev_warn(&dev->dev,
					 "TX queue failure: out of memory\n");
		} else {
			dev->stats.tx_fifo_errors++;
			if (net_ratelimit())
				dev_warn(&dev->dev,
					 "Unexpected TX queue failure: %d\n",
					 capacity);
		}
		dev->stats.tx_dropped++;
		kfree_skb(skb);
		return NETDEV_TX_OK;
	}
	virtqueue_kick(vi->svq);

	/* Don't wait up for transmitted skbs to be freed. */
	skb_orphan(skb);
	nf_reset(skb);

	/* Apparently nice girls don't return TX_BUSY; stop the queue
	 * before it gets out of hand.  Naturally, this wastes entries. */
	if (capacity < 2+MAX_SKB_FRAGS) {
		netif_stop_queue(dev);
		if (unlikely(!virtqueue_enable_cb_delayed(vi->svq))) {
			/* More just got used, free them then recheck. */
			capacity += free_old_xmit_skbs(vi);
			if (capacity >= 2+MAX_SKB_FRAGS) {
				netif_start_queue(dev);
				virtqueue_disable_cb(vi->svq);
			}
		}
	}

	return NETDEV_TX_OK;
}

static int virtnet_set_mac_address(struct net_device *dev, void *p)
{
	struct virtnet_info *vi = netdev_priv(dev);
	struct virtio_device *vdev = vi->vdev;
	int ret;

	ret = eth_mac_addr(dev, p);
	if (ret)
		return ret;

	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
		vdev->config->set(vdev, offsetof(struct virtio_net_config, mac),
		                  dev->dev_addr, dev->addr_len);

	return 0;
}

static struct rtnl_link_stats64 *virtnet_stats(struct net_device *dev,
					       struct rtnl_link_stats64 *tot)
{
	struct virtnet_info *vi = netdev_priv(dev);
	int cpu;
	unsigned int start;

	for_each_possible_cpu(cpu) {
		struct virtnet_stats *stats = per_cpu_ptr(vi->stats, cpu);
		u64 tpackets, tbytes, rpackets, rbytes;

		do {
			start = u64_stats_fetch_begin(&stats->syncp);
			tpackets = stats->tx_packets;
			tbytes   = stats->tx_bytes;
			rpackets = stats->rx_packets;
			rbytes   = stats->rx_bytes;
		} while (u64_stats_fetch_retry(&stats->syncp, start));

		tot->rx_packets += rpackets;
		tot->tx_packets += tpackets;
		tot->rx_bytes   += rbytes;
		tot->tx_bytes   += tbytes;
	}

	tot->tx_dropped = dev->stats.tx_dropped;
	tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
	tot->rx_dropped = dev->stats.rx_dropped;
	tot->rx_length_errors = dev->stats.rx_length_errors;
	tot->rx_frame_errors = dev->stats.rx_frame_errors;

	return tot;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void virtnet_netpoll(struct net_device *dev)
{
	struct virtnet_info *vi = netdev_priv(dev);

	napi_schedule(&vi->napi);
}
#endif

static int virtnet_open(struct net_device *dev)
{
	struct virtnet_info *vi = netdev_priv(dev);

	/* Make sure we have some buffers: if oom use wq. */
	if (!try_fill_recv(vi, GFP_KERNEL))
		queue_delayed_work(system_nrt_wq, &vi->refill, 0);

	virtnet_napi_enable(vi);
	return 0;
}

/*
 * Send command via the control virtqueue and check status.  Commands
 * supported by the hypervisor, as indicated by feature bits, should
 * never fail unless improperly formated.
 */
static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
				 struct scatterlist *data, int out, int in)
{
	struct scatterlist *s, sg[VIRTNET_SEND_COMMAND_SG_MAX + 2];
	struct virtio_net_ctrl_hdr ctrl;
	virtio_net_ctrl_ack status = ~0;
	unsigned int tmp;
	int i;

	/* Caller should know better */
	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) ||
		(out + in > VIRTNET_SEND_COMMAND_SG_MAX));

	out++; /* Add header */
	in++; /* Add return status */

	ctrl.class = class;
	ctrl.cmd = cmd;

	sg_init_table(sg, out + in);

	sg_set_buf(&sg[0], &ctrl, sizeof(ctrl));
	for_each_sg(data, s, out + in - 2, i)
		sg_set_buf(&sg[i + 1], sg_virt(s), s->length);
	sg_set_buf(&sg[out + in - 1], &status, sizeof(status));

	BUG_ON(virtqueue_add_buf(vi->cvq, sg, out, in, vi, GFP_ATOMIC) < 0);

	virtqueue_kick(vi->cvq);

	/*
	 * Spin for a response, the kick causes an ioport write, trapping
	 * into the hypervisor, so the request should be handled immediately.
	 */
	while (!virtqueue_get_buf(vi->cvq, &tmp))
		cpu_relax();

	return status == VIRTIO_NET_OK;
}

static int virtnet_close(struct net_device *dev)
{
	struct virtnet_info *vi = netdev_priv(dev);

	/* Make sure refill_work doesn't re-enable napi! */
	cancel_delayed_work_sync(&vi->refill);
	napi_disable(&vi->napi);

	return 0;
}

static void virtnet_set_rx_mode(struct net_device *dev)
{
	struct virtnet_info *vi = netdev_priv(dev);
	struct scatterlist sg[2];
	u8 promisc, allmulti;
	struct virtio_net_ctrl_mac *mac_data;
	struct netdev_hw_addr *ha;
	int uc_count;
	int mc_count;
	void *buf;
	int i;

	/* We can't dynamicaly set ndo_set_rx_mode, so return gracefully */
	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))
		return;

	promisc = ((dev->flags & IFF_PROMISC) != 0);
	allmulti = ((dev->flags & IFF_ALLMULTI) != 0);

	sg_init_one(sg, &promisc, sizeof(promisc));

	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
				  VIRTIO_NET_CTRL_RX_PROMISC,
				  sg, 1, 0))
		dev_warn(&dev->dev, "Failed to %sable promisc mode.\n",
			 promisc ? "en" : "dis");

	sg_init_one(sg, &allmulti, sizeof(allmulti));

	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
				  VIRTIO_NET_CTRL_RX_ALLMULTI,
				  sg, 1, 0))
		dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
			 allmulti ? "en" : "dis");

	uc_count = netdev_uc_count(dev);
	mc_count = netdev_mc_count(dev);
	/* MAC filter - use one buffer for both lists */
	buf = kzalloc(((uc_count + mc_count) * ETH_ALEN) +
		      (2 * sizeof(mac_data->entries)), GFP_ATOMIC);
	mac_data = buf;
	if (!buf) {
		dev_warn(&dev->dev, "No memory for MAC address buffer\n");
		return;
	}

	sg_init_table(sg, 2);

	/* Store the unicast list and count in the front of the buffer */
	mac_data->entries = uc_count;
	i = 0;
	netdev_for_each_uc_addr(ha, dev)
		memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);

	sg_set_buf(&sg[0], mac_data,
		   sizeof(mac_data->entries) + (uc_count * ETH_ALEN));

	/* multicast list and count fill the end */
	mac_data = (void *)&mac_data->macs[uc_count][0];

	mac_data->entries = mc_count;
	i = 0;
	netdev_for_each_mc_addr(ha, dev)
		memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);

	sg_set_buf(&sg[1], mac_data,
		   sizeof(mac_data->entries) + (mc_count * ETH_ALEN));

	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
				  VIRTIO_NET_CTRL_MAC_TABLE_SET,
				  sg, 2, 0))
		dev_warn(&dev->dev, "Failed to set MAC fitler table.\n");

	kfree(buf);
}

static int virtnet_vlan_rx_add_vid(struct net_device *dev, u16 vid)
{
	struct virtnet_info *vi = netdev_priv(dev);
	struct scatterlist sg;

	sg_init_one(&sg, &vid, sizeof(vid));

	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
				  VIRTIO_NET_CTRL_VLAN_ADD, &sg, 1, 0))
		dev_warn(&dev->dev, "Failed to add VLAN ID %d.\n", vid);
	return 0;
}

static int virtnet_vlan_rx_kill_vid(struct net_device *dev, u16 vid)
{
	struct virtnet_info *vi = netdev_priv(dev);
	struct scatterlist sg;

	sg_init_one(&sg, &vid, sizeof(vid));

	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
				  VIRTIO_NET_CTRL_VLAN_DEL, &sg, 1, 0))
		dev_warn(&dev->dev, "Failed to kill VLAN ID %d.\n", vid);
	return 0;
}

static void virtnet_get_ringparam(struct net_device *dev,
				struct ethtool_ringparam *ring)
{
	struct virtnet_info *vi = netdev_priv(dev);

	ring->rx_max_pending = virtqueue_get_vring_size(vi->rvq);
	ring->tx_max_pending = virtqueue_get_vring_size(vi->svq);
	ring->rx_pending = ring->rx_max_pending;
	ring->tx_pending = ring->tx_max_pending;

}


static void virtnet_get_drvinfo(struct net_device *dev,
				struct ethtool_drvinfo *info)
{
	struct virtnet_info *vi = netdev_priv(dev);
	struct virtio_device *vdev = vi->vdev;

	strlcpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
	strlcpy(info->version, VIRTNET_DRIVER_VERSION, sizeof(info->version));
	strlcpy(info->bus_info, virtio_bus_name(vdev), sizeof(info->bus_info));

}

static const struct ethtool_ops virtnet_ethtool_ops = {
	.get_drvinfo = virtnet_get_drvinfo,
	.get_link = ethtool_op_get_link,
	.get_ringparam = virtnet_get_ringparam,
};

#define MIN_MTU 68
#define MAX_MTU 65535

static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
{
	if (new_mtu < MIN_MTU || new_mtu > MAX_MTU)
		return -EINVAL;
	dev->mtu = new_mtu;
	return 0;
}

static const struct net_device_ops virtnet_netdev = {
	.ndo_open            = virtnet_open,
	.ndo_stop   	     = virtnet_close,
	.ndo_start_xmit      = start_xmit,
	.ndo_validate_addr   = eth_validate_addr,
	.ndo_set_mac_address = virtnet_set_mac_address,
	.ndo_set_rx_mode     = virtnet_set_rx_mode,
	.ndo_change_mtu	     = virtnet_change_mtu,
	.ndo_get_stats64     = virtnet_stats,
	.ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
	.ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
#ifdef CONFIG_NET_POLL_CONTROLLER
	.ndo_poll_controller = virtnet_netpoll,
#endif
};

static void virtnet_update_status(struct virtnet_info *vi)
{
	u16 v;

	if (virtio_config_val(vi->vdev, VIRTIO_NET_F_STATUS,
			      offsetof(struct virtio_net_config, status),
			      &v) < 0)
		return;

	/* Ignore unknown (future) status bits */
	v &= VIRTIO_NET_S_LINK_UP;

	if (vi->status == v)
		return;

	vi->status = v;

	if (vi->status & VIRTIO_NET_S_LINK_UP) {
		netif_carrier_on(vi->dev);
		netif_wake_queue(vi->dev);
	} else {
		netif_carrier_off(vi->dev);
		netif_stop_queue(vi->dev);
	}
}

static void virtnet_config_changed(struct virtio_device *vdev)
{
	struct virtnet_info *vi = vdev->priv;

	virtnet_update_status(vi);
}

static int init_vqs(struct virtnet_info *vi)
{
	struct virtqueue *vqs[3];
	vq_callback_t *callbacks[] = { skb_recv_done, skb_xmit_done, NULL};
	const char *names[] = { "input", "output", "control" };
	int nvqs, err;

	/* We expect two virtqueues, receive then send,
	 * and optionally control. */
	nvqs = virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) ? 3 : 2;

	err = vi->vdev->config->find_vqs(vi->vdev, nvqs, vqs, callbacks, names);
	if (err)
		return err;

	vi->rvq = vqs[0];
	vi->svq = vqs[1];

	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) {
		vi->cvq = vqs[2];

		if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
			vi->dev->features |= NETIF_F_HW_VLAN_FILTER;
	}
	return 0;
}

static int virtnet_probe(struct virtio_device *vdev)
{
	int err;
	struct net_device *dev;
	struct virtnet_info *vi;

	/* Allocate ourselves a network device with room for our info */
	dev = alloc_etherdev(sizeof(struct virtnet_info));
	if (!dev)
		return -ENOMEM;

	/* Set up network device as normal. */
	dev->priv_flags |= IFF_UNICAST_FLT;
	dev->netdev_ops = &virtnet_netdev;
	dev->features = NETIF_F_HIGHDMA;

	SET_ETHTOOL_OPS(dev, &virtnet_ethtool_ops);
	SET_NETDEV_DEV(dev, &vdev->dev);

	/* Do we support "hardware" checksums? */
	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
		/* This opens up the world of extra features. */
		dev->hw_features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
		if (csum)
			dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;

		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
			dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
				| NETIF_F_TSO_ECN | NETIF_F_TSO6;
		}
		/* Individual feature bits: what can host handle? */
		if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
			dev->hw_features |= NETIF_F_TSO;
		if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
			dev->hw_features |= NETIF_F_TSO6;
		if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
			dev->hw_features |= NETIF_F_TSO_ECN;
		if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
			dev->hw_features |= NETIF_F_UFO;

		if (gso)
			dev->features |= dev->hw_features & (NETIF_F_ALL_TSO|NETIF_F_UFO);
		/* (!csum && gso) case will be fixed by register_netdev() */
	}

	/* Configuration may specify what MAC to use.  Otherwise random. */
	if (virtio_config_val_len(vdev, VIRTIO_NET_F_MAC,
				  offsetof(struct virtio_net_config, mac),
				  dev->dev_addr, dev->addr_len) < 0)
		eth_hw_addr_random(dev);

	/* Set up our device-specific information */
	vi = netdev_priv(dev);
	netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
	vi->dev = dev;
	vi->vdev = vdev;
	vdev->priv = vi;
	vi->pages = NULL;
	vi->stats = alloc_percpu(struct virtnet_stats);
	err = -ENOMEM;
	if (vi->stats == NULL)
		goto free;

	INIT_DELAYED_WORK(&vi->refill, refill_work);
	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));
	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));

	/* If we can receive ANY GSO packets, we must allocate large ones. */
	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
	    virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6) ||
	    virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN))
		vi->big_packets = true;

	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
		vi->mergeable_rx_bufs = true;

	err = init_vqs(vi);
	if (err)
		goto free_stats;

	err = register_netdev(dev);
	if (err) {
		pr_debug("virtio_net: registering device failed\n");
		goto free_vqs;
	}

	/* Last of all, set up some receive buffers. */
	try_fill_recv(vi, GFP_KERNEL);

	/* If we didn't even get one input buffer, we're useless. */
	if (vi->num == 0) {
		err = -ENOMEM;
		goto unregister;
	}

	/* Assume link up if device can't report link status,
	   otherwise get link status from config. */
	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
		netif_carrier_off(dev);
		virtnet_update_status(vi);
	} else {
		vi->status = VIRTIO_NET_S_LINK_UP;
		netif_carrier_on(dev);
	}

	pr_debug("virtnet: registered device %s\n", dev->name);
	return 0;

unregister:
	unregister_netdev(dev);
free_vqs:
	vdev->config->del_vqs(vdev);
free_stats:
	free_percpu(vi->stats);
free:
	free_netdev(dev);
	return err;
}

static void free_unused_bufs(struct virtnet_info *vi)
{
	void *buf;
	while (1) {
		buf = virtqueue_detach_unused_buf(vi->svq);
		if (!buf)
			break;
		dev_kfree_skb(buf);
	}
	while (1) {
		buf = virtqueue_detach_unused_buf(vi->rvq);
		if (!buf)
			break;
		if (vi->mergeable_rx_bufs || vi->big_packets)
			give_pages(vi, buf);
		else
			dev_kfree_skb(buf);
		--vi->num;
	}
	BUG_ON(vi->num != 0);
}

static void remove_vq_common(struct virtnet_info *vi)
{
	vi->vdev->config->reset(vi->vdev);

	/* Free unused buffers in both send and recv, if any. */
	free_unused_bufs(vi);

	vi->vdev->config->del_vqs(vi->vdev);

	while (vi->pages)
		__free_pages(get_a_page(vi, GFP_KERNEL), 0);
}

static void __devexit virtnet_remove(struct virtio_device *vdev)
{
	struct virtnet_info *vi = vdev->priv;

	unregister_netdev(vi->dev);

	remove_vq_common(vi);

	free_percpu(vi->stats);
	free_netdev(vi->dev);
}

#ifdef CONFIG_PM
static int virtnet_freeze(struct virtio_device *vdev)
{
	struct virtnet_info *vi = vdev->priv;

	virtqueue_disable_cb(vi->rvq);
	virtqueue_disable_cb(vi->svq);
	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
		virtqueue_disable_cb(vi->cvq);

	netif_device_detach(vi->dev);
	cancel_delayed_work_sync(&vi->refill);

	if (netif_running(vi->dev))
		napi_disable(&vi->napi);

	remove_vq_common(vi);

	return 0;
}

static int virtnet_restore(struct virtio_device *vdev)
{
	struct virtnet_info *vi = vdev->priv;
	int err;

	err = init_vqs(vi);
	if (err)
		return err;

	if (netif_running(vi->dev))
		virtnet_napi_enable(vi);

	netif_device_attach(vi->dev);

	if (!try_fill_recv(vi, GFP_KERNEL))
		queue_delayed_work(system_nrt_wq, &vi->refill, 0);

	return 0;
}
#endif

static struct virtio_device_id id_table[] = {
	{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
	{ 0 },
};

static unsigned int features[] = {
	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,
	VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
};

static struct virtio_driver virtio_net_driver = {
	.feature_table = features,
	.feature_table_size = ARRAY_SIZE(features),
	.driver.name =	KBUILD_MODNAME,
	.driver.owner =	THIS_MODULE,
	.id_table =	id_table,
	.probe =	virtnet_probe,
	.remove =	__devexit_p(virtnet_remove),
	.config_changed = virtnet_config_changed,
#ifdef CONFIG_PM
	.freeze =	virtnet_freeze,
	.restore =	virtnet_restore,
#endif
};

static int __init init(void)
{
	return register_virtio_driver(&virtio_net_driver);
}

static void __exit fini(void)
{
	unregister_virtio_driver(&virtio_net_driver);
}
module_init(init);
module_exit(fini);

MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio network driver");
MODULE_LICENSE("GPL");