net/core/gro.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <net/gro.h>
   3 #include <net/dst_metadata.h>
   4 #include <net/busy_poll.h>
   5 #include <trace/events/net.h>
   6
   7 #define MAX_GRO_SKBS 8
   8
   9 /* This should be increased if a protocol with a bigger head is added. */
  10 #define GRO_MAX_HEAD (MAX_HEADER + 128)
  11
  12 static DEFINE_SPINLOCK(offload_lock);
  13 struct list_head offload_base __read_mostly = LIST_HEAD_INIT(offload_base);
  14 /* Maximum number of GRO_NORMAL skbs to batch up for list-RX */
  15 int gro_normal_batch __read_mostly = 8;
  16
  17 /**
  18  *      dev_add_offload - register offload handlers
  19  *      @po: protocol offload declaration
  20  *
  21  *      Add protocol offload handlers to the networking stack. The passed
  22  *      &proto_offload is linked into kernel lists and may not be freed until
  23  *      it has been removed from the kernel lists.
  24  *
  25  *      This call does not sleep therefore it can not
  26  *      guarantee all CPU's that are in middle of receiving packets
  27  *      will see the new offload handlers (until the next received packet).
  28  */
  29 void dev_add_offload(struct packet_offload *po)
  30 {
  31         struct packet_offload *elem;
  32
  33         spin_lock(&offload_lock);
  34         list_for_each_entry(elem, &offload_base, list) {
  35                 if (po->priority < elem->priority)
  36                         break;
  37         }
  38         list_add_rcu(&po->list, elem->list.prev);
  39         spin_unlock(&offload_lock);
  40 }
  41 EXPORT_SYMBOL(dev_add_offload);
  42
  43 /**
  44  *      __dev_remove_offload     - remove offload handler
  45  *      @po: packet offload declaration
  46  *
  47  *      Remove a protocol offload handler that was previously added to the
  48  *      kernel offload handlers by dev_add_offload(). The passed &offload_type
  49  *      is removed from the kernel lists and can be freed or reused once this
  50  *      function returns.
  51  *
  52  *      The packet type might still be in use by receivers
  53  *      and must not be freed until after all the CPU's have gone
  54  *      through a quiescent state.
  55  */
  56 static void __dev_remove_offload(struct packet_offload *po)
  57 {
  58         struct list_head *head = &offload_base;
  59         struct packet_offload *po1;
  60
  61         spin_lock(&offload_lock);
  62
  63         list_for_each_entry(po1, head, list) {
  64                 if (po == po1) {
  65                         list_del_rcu(&po->list);
  66                         goto out;
  67                 }
  68         }
  69
  70         pr_warn("dev_remove_offload: %p not found\n", po);
  71 out:
  72         spin_unlock(&offload_lock);
  73 }
  74
  75 /**
  76  *      dev_remove_offload       - remove packet offload handler
  77  *      @po: packet offload declaration
  78  *
  79  *      Remove a packet offload handler that was previously added to the kernel
  80  *      offload handlers by dev_add_offload(). The passed &offload_type is
  81  *      removed from the kernel lists and can be freed or reused once this
  82  *      function returns.
  83  *
  84  *      This call sleeps to guarantee that no CPU is looking at the packet
  85  *      type after return.
  86  */
  87 void dev_remove_offload(struct packet_offload *po)
  88 {
  89         __dev_remove_offload(po);
  90
  91         synchronize_net();
  92 }
  93 EXPORT_SYMBOL(dev_remove_offload);
  94
  95
  96 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
  97 {
  98         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
  99         unsigned int offset = skb_gro_offset(skb);
 100         unsigned int headlen = skb_headlen(skb);
 101         unsigned int len = skb_gro_len(skb);
 102         unsigned int delta_truesize;
 103         unsigned int gro_max_size;
 104         unsigned int new_truesize;
 105         struct sk_buff *lp;
 106         int segs;
 107
 108         /* Do not splice page pool based packets w/ non-page pool
 109          * packets. This can result in reference count issues as page
 110          * pool pages will not decrement the reference count and will
 111          * instead be immediately returned to the pool or have frag
 112          * count decremented.
 113          */
 114         if (p->pp_recycle != skb->pp_recycle)
 115                 return -ETOOMANYREFS;
 116
 117         /* pairs with WRITE_ONCE() in netif_set_gro(_ipv4)_max_size() */
 118         gro_max_size = p->protocol == htons(ETH_P_IPV6) ?
 119                         READ_ONCE(p->dev->gro_max_size) :
 120                         READ_ONCE(p->dev->gro_ipv4_max_size);
 121
 122         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 123                 return -E2BIG;
 124
 125         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 126                 if (NAPI_GRO_CB(skb)->proto != IPPROTO_TCP ||
 127                     (p->protocol == htons(ETH_P_IPV6) &&
 128                      skb_headroom(p) < sizeof(struct hop_jumbo_hdr)) ||
 129                     p->encapsulation)
 130                         return -E2BIG;
 131         }
 132
 133         segs = NAPI_GRO_CB(skb)->count;
 134         lp = NAPI_GRO_CB(p)->last;
 135         pinfo = skb_shinfo(lp);
 136
 137         if (headlen <= offset) {
 138                 skb_frag_t *frag;
 139                 skb_frag_t *frag2;
 140                 int i = skbinfo->nr_frags;
 141                 int nr_frags = pinfo->nr_frags + i;
 142
 143                 if (nr_frags > MAX_SKB_FRAGS)
 144                         goto merge;
 145
 146                 offset -= headlen;
 147                 pinfo->nr_frags = nr_frags;
 148                 skbinfo->nr_frags = 0;
 149
 150                 frag = pinfo->frags + nr_frags;
 151                 frag2 = skbinfo->frags + i;
 152                 do {
 153                         *--frag = *--frag2;
 154                 } while (--i);
 155
 156                 skb_frag_off_add(frag, offset);
 157                 skb_frag_size_sub(frag, offset);
 158
 159                 /* all fragments truesize : remove (head size + sk_buff) */
 160                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 161                 delta_truesize = skb->truesize - new_truesize;
 162
 163                 skb->truesize = new_truesize;
 164                 skb->len -= skb->data_len;
 165                 skb->data_len = 0;
 166
 167                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 168                 goto done;
 169         } else if (skb->head_frag) {
 170                 int nr_frags = pinfo->nr_frags;
 171                 skb_frag_t *frag = pinfo->frags + nr_frags;
 172                 struct page *page = virt_to_head_page(skb->head);
 173                 unsigned int first_size = headlen - offset;
 174                 unsigned int first_offset;
 175
 176                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 177                         goto merge;
 178
 179                 first_offset = skb->data -
 180                                (unsigned char *)page_address(page) +
 181                                offset;
 182
 183                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 184
 185                 skb_frag_fill_page_desc(frag, page, first_offset, first_size);
 186
 187                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 188                 /* We dont need to clear skbinfo->nr_frags here */
 189
 190                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 191                 delta_truesize = skb->truesize - new_truesize;
 192                 skb->truesize = new_truesize;
 193                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 194                 goto done;
 195         }
 196
 197 merge:
 198         /* sk owenrship - if any - completely transferred to the aggregated packet */
 199         skb->destructor = NULL;
 200         delta_truesize = skb->truesize;
 201         if (offset > headlen) {
 202                 unsigned int eat = offset - headlen;
 203
 204                 skb_frag_off_add(&skbinfo->frags[0], eat);
 205                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 206                 skb->data_len -= eat;
 207                 skb->len -= eat;
 208                 offset = headlen;
 209         }
 210
 211         __skb_pull(skb, offset);
 212
 213         if (NAPI_GRO_CB(p)->last == p)
 214                 skb_shinfo(p)->frag_list = skb;
 215         else
 216                 NAPI_GRO_CB(p)->last->next = skb;
 217         NAPI_GRO_CB(p)->last = skb;
 218         __skb_header_release(skb);
 219         lp = p;
 220
 221 done:
 222         NAPI_GRO_CB(p)->count += segs;
 223         p->data_len += len;
 224         p->truesize += delta_truesize;
 225         p->len += len;
 226         if (lp != p) {
 227                 lp->data_len += len;
 228                 lp->truesize += delta_truesize;
 229                 lp->len += len;
 230         }
 231         NAPI_GRO_CB(skb)->same_flow = 1;
 232         return 0;
 233 }
 234
 235
 236 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 237 {
 238         struct packet_offload *ptype;
 239         __be16 type = skb->protocol;
 240         struct list_head *head = &offload_base;
 241         int err = -ENOENT;
 242
 243         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 244
 245         if (NAPI_GRO_CB(skb)->count == 1) {
 246                 skb_shinfo(skb)->gso_size = 0;
 247                 goto out;
 248         }
 249
 250         rcu_read_lock();
 251         list_for_each_entry_rcu(ptype, head, list) {
 252                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 253                         continue;
 254
 255                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 256                                          ipv6_gro_complete, inet_gro_complete,
 257                                          skb, 0);
 258                 break;
 259         }
 260         rcu_read_unlock();
 261
 262         if (err) {
 263                 WARN_ON(&ptype->list == head);
 264                 kfree_skb(skb);
 265                 return;
 266         }
 267
 268 out:
 269         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 270 }
 271
 272 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 273                                    bool flush_old)
 274 {
 275         struct list_head *head = &napi->gro_hash[index].list;
 276         struct sk_buff *skb, *p;
 277
 278         list_for_each_entry_safe_reverse(skb, p, head, list) {
 279                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 280                         return;
 281                 skb_list_del_init(skb);
 282                 napi_gro_complete(napi, skb);
 283                 napi->gro_hash[index].count--;
 284         }
 285
 286         if (!napi->gro_hash[index].count)
 287                 __clear_bit(index, &napi->gro_bitmask);
 288 }
 289
 290 /* napi->gro_hash[].list contains packets ordered by age.
 291  * youngest packets at the head of it.
 292  * Complete skbs in reverse order to reduce latencies.
 293  */
 294 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 295 {
 296         unsigned long bitmask = napi->gro_bitmask;
 297         unsigned int i, base = ~0U;
 298
 299         while ((i = ffs(bitmask)) != 0) {
 300                 bitmask >>= i;
 301                 base += i;
 302                 __napi_gro_flush_chain(napi, base, flush_old);
 303         }
 304 }
 305 EXPORT_SYMBOL(napi_gro_flush);
 306
 307 static unsigned long gro_list_prepare_tc_ext(const struct sk_buff *skb,
 308                                              const struct sk_buff *p,
 309                                              unsigned long diffs)
 310 {
 311 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 312         struct tc_skb_ext *skb_ext;
 313         struct tc_skb_ext *p_ext;
 314
 315         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 316         p_ext = skb_ext_find(p, TC_SKB_EXT);
 317
 318         diffs |= (!!p_ext) ^ (!!skb_ext);
 319         if (!diffs && unlikely(skb_ext))
 320                 diffs |= p_ext->chain ^ skb_ext->chain;
 321 #endif
 322         return diffs;
 323 }
 324
 325 static void gro_list_prepare(const struct list_head *head,
 326                              const struct sk_buff *skb)
 327 {
 328         unsigned int maclen = skb->dev->hard_header_len;
 329         u32 hash = skb_get_hash_raw(skb);
 330         struct sk_buff *p;
 331
 332         list_for_each_entry(p, head, list) {
 333                 unsigned long diffs;
 334
 335                 NAPI_GRO_CB(p)->flush = 0;
 336
 337                 if (hash != skb_get_hash_raw(p)) {
 338                         NAPI_GRO_CB(p)->same_flow = 0;
 339                         continue;
 340                 }
 341
 342                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 343                 diffs |= p->vlan_all ^ skb->vlan_all;
 344                 diffs |= skb_metadata_differs(p, skb);
 345                 if (maclen == ETH_HLEN)
 346                         diffs |= compare_ether_header(skb_mac_header(p),
 347                                                       skb_mac_header(skb));
 348                 else if (!diffs)
 349                         diffs = memcmp(skb_mac_header(p),
 350                                        skb_mac_header(skb),
 351                                        maclen);
 352
 353                 /* in most common scenarions 'slow_gro' is 0
 354                  * otherwise we are already on some slower paths
 355                  * either skip all the infrequent tests altogether or
 356                  * avoid trying too hard to skip each of them individually
 357                  */
 358                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 359                         diffs |= p->sk != skb->sk;
 360                         diffs |= skb_metadata_dst_cmp(p, skb);
 361                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 362
 363                         diffs |= gro_list_prepare_tc_ext(skb, p, diffs);
 364                 }
 365
 366                 NAPI_GRO_CB(p)->same_flow = !diffs;
 367         }
 368 }
 369
 370 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 371 {
 372         const struct skb_shared_info *pinfo = skb_shinfo(skb);
 373         const skb_frag_t *frag0 = &pinfo->frags[0];
 374
 375         NAPI_GRO_CB(skb)->data_offset = 0;
 376         NAPI_GRO_CB(skb)->frag0 = NULL;
 377         NAPI_GRO_CB(skb)->frag0_len = 0;
 378
 379         if (!skb_headlen(skb) && pinfo->nr_frags &&
 380             !PageHighMem(skb_frag_page(frag0)) &&
 381             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 382                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 383                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 384                                                     skb_frag_size(frag0),
 385                                                     skb->end - skb->tail);
 386         }
 387 }
 388
 389 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 390 {
 391         struct skb_shared_info *pinfo = skb_shinfo(skb);
 392
 393         BUG_ON(skb->end - skb->tail < grow);
 394
 395         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 396
 397         skb->data_len -= grow;
 398         skb->tail += grow;
 399
 400         skb_frag_off_add(&pinfo->frags[0], grow);
 401         skb_frag_size_sub(&pinfo->frags[0], grow);
 402
 403         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 404                 skb_frag_unref(skb, 0);
 405                 memmove(pinfo->frags, pinfo->frags + 1,
 406                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 407         }
 408 }
 409
 410 static void gro_try_pull_from_frag0(struct sk_buff *skb)
 411 {
 412         int grow = skb_gro_offset(skb) - skb_headlen(skb);
 413
 414         if (grow > 0)
 415                 gro_pull_from_frag0(skb, grow);
 416 }
 417
 418 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 419 {
 420         struct sk_buff *oldest;
 421
 422         oldest = list_last_entry(head, struct sk_buff, list);
 423
 424         /* We are called with head length >= MAX_GRO_SKBS, so this is
 425          * impossible.
 426          */
 427         if (WARN_ON_ONCE(!oldest))
 428                 return;
 429
 430         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 431          * SKB to the chain.
 432          */
 433         skb_list_del_init(oldest);
 434         napi_gro_complete(napi, oldest);
 435 }
 436
 437 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 438 {
 439         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 440         struct gro_list *gro_list = &napi->gro_hash[bucket];
 441         struct list_head *head = &offload_base;
 442         struct packet_offload *ptype;
 443         __be16 type = skb->protocol;
 444         struct sk_buff *pp = NULL;
 445         enum gro_result ret;
 446         int same_flow;
 447
 448         if (netif_elide_gro(skb->dev))
 449                 goto normal;
 450
 451         gro_list_prepare(&gro_list->list, skb);
 452
 453         rcu_read_lock();
 454         list_for_each_entry_rcu(ptype, head, list) {
 455                 if (ptype->type == type && ptype->callbacks.gro_receive)
 456                         goto found_ptype;
 457         }
 458         rcu_read_unlock();
 459         goto normal;
 460
 461 found_ptype:
 462         skb_set_network_header(skb, skb_gro_offset(skb));
 463         skb_reset_mac_len(skb);
 464         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 465         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 466                                         sizeof(u32))); /* Avoid slow unaligned acc */
 467         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 468         NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 469         NAPI_GRO_CB(skb)->is_atomic = 1;
 470         NAPI_GRO_CB(skb)->count = 1;
 471         if (unlikely(skb_is_gso(skb))) {
 472                 NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 473                 /* Only support TCP and non DODGY users. */
 474                 if (!skb_is_gso_tcp(skb) ||
 475                     (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 476                         NAPI_GRO_CB(skb)->flush = 1;
 477         }
 478
 479         /* Setup for GRO checksum validation */
 480         switch (skb->ip_summed) {
 481         case CHECKSUM_COMPLETE:
 482                 NAPI_GRO_CB(skb)->csum = skb->csum;
 483                 NAPI_GRO_CB(skb)->csum_valid = 1;
 484                 break;
 485         case CHECKSUM_UNNECESSARY:
 486                 NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 487                 break;
 488         }
 489
 490         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 491                                 ipv6_gro_receive, inet_gro_receive,
 492                                 &gro_list->list, skb);
 493
 494         rcu_read_unlock();
 495
 496         if (PTR_ERR(pp) == -EINPROGRESS) {
 497                 ret = GRO_CONSUMED;
 498                 goto ok;
 499         }
 500
 501         same_flow = NAPI_GRO_CB(skb)->same_flow;
 502         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 503
 504         if (pp) {
 505                 skb_list_del_init(pp);
 506                 napi_gro_complete(napi, pp);
 507                 gro_list->count--;
 508         }
 509
 510         if (same_flow)
 511                 goto ok;
 512
 513         if (NAPI_GRO_CB(skb)->flush)
 514                 goto normal;
 515
 516         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 517                 gro_flush_oldest(napi, &gro_list->list);
 518         else
 519                 gro_list->count++;
 520
 521         /* Must be called before setting NAPI_GRO_CB(skb)->{age|last} */
 522         gro_try_pull_from_frag0(skb);
 523         NAPI_GRO_CB(skb)->age = jiffies;
 524         NAPI_GRO_CB(skb)->last = skb;
 525         if (!skb_is_gso(skb))
 526                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 527         list_add(&skb->list, &gro_list->list);
 528         ret = GRO_HELD;
 529 ok:
 530         if (gro_list->count) {
 531                 if (!test_bit(bucket, &napi->gro_bitmask))
 532                         __set_bit(bucket, &napi->gro_bitmask);
 533         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 534                 __clear_bit(bucket, &napi->gro_bitmask);
 535         }
 536
 537         return ret;
 538
 539 normal:
 540         ret = GRO_NORMAL;
 541         gro_try_pull_from_frag0(skb);
 542         goto ok;
 543 }
 544
 545 struct packet_offload *gro_find_receive_by_type(__be16 type)
 546 {
 547         struct list_head *offload_head = &offload_base;
 548         struct packet_offload *ptype;
 549
 550         list_for_each_entry_rcu(ptype, offload_head, list) {
 551                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 552                         continue;
 553                 return ptype;
 554         }
 555         return NULL;
 556 }
 557 EXPORT_SYMBOL(gro_find_receive_by_type);
 558
 559 struct packet_offload *gro_find_complete_by_type(__be16 type)
 560 {
 561         struct list_head *offload_head = &offload_base;
 562         struct packet_offload *ptype;
 563
 564         list_for_each_entry_rcu(ptype, offload_head, list) {
 565                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 566                         continue;
 567                 return ptype;
 568         }
 569         return NULL;
 570 }
 571 EXPORT_SYMBOL(gro_find_complete_by_type);
 572
 573 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 574                                     struct sk_buff *skb,
 575                                     gro_result_t ret)
 576 {
 577         switch (ret) {
 578         case GRO_NORMAL:
 579                 gro_normal_one(napi, skb, 1);
 580                 break;
 581
 582         case GRO_MERGED_FREE:
 583                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 584                         napi_skb_free_stolen_head(skb);
 585                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 586                         __kfree_skb(skb);
 587                 else
 588                         __napi_kfree_skb(skb, SKB_CONSUMED);
 589                 break;
 590
 591         case GRO_HELD:
 592         case GRO_MERGED:
 593         case GRO_CONSUMED:
 594                 break;
 595         }
 596
 597         return ret;
 598 }
 599
 600 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 601 {
 602         gro_result_t ret;
 603
 604         skb_mark_napi_id(skb, napi);
 605         trace_napi_gro_receive_entry(skb);
 606
 607         skb_gro_reset_offset(skb, 0);
 608
 609         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 610         trace_napi_gro_receive_exit(ret);
 611
 612         return ret;
 613 }
 614 EXPORT_SYMBOL(napi_gro_receive);
 615
 616 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 617 {
 618         if (unlikely(skb->pfmemalloc)) {
 619                 consume_skb(skb);
 620                 return;
 621         }
 622         __skb_pull(skb, skb_headlen(skb));
 623         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 624         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 625         __vlan_hwaccel_clear_tag(skb);
 626         skb->dev = napi->dev;
 627         skb->skb_iif = 0;
 628
 629         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 630         skb->pkt_type = PACKET_HOST;
 631
 632         skb->encapsulation = 0;
 633         skb_shinfo(skb)->gso_type = 0;
 634         skb_shinfo(skb)->gso_size = 0;
 635         if (unlikely(skb->slow_gro)) {
 636                 skb_orphan(skb);
 637                 skb_ext_reset(skb);
 638                 nf_reset_ct(skb);
 639                 skb->slow_gro = 0;
 640         }
 641
 642         napi->skb = skb;
 643 }
 644
 645 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 646 {
 647         struct sk_buff *skb = napi->skb;
 648
 649         if (!skb) {
 650                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 651                 if (skb) {
 652                         napi->skb = skb;
 653                         skb_mark_napi_id(skb, napi);
 654                 }
 655         }
 656         return skb;
 657 }
 658 EXPORT_SYMBOL(napi_get_frags);
 659
 660 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 661                                       struct sk_buff *skb,
 662                                       gro_result_t ret)
 663 {
 664         switch (ret) {
 665         case GRO_NORMAL:
 666         case GRO_HELD:
 667                 __skb_push(skb, ETH_HLEN);
 668                 skb->protocol = eth_type_trans(skb, skb->dev);
 669                 if (ret == GRO_NORMAL)
 670                         gro_normal_one(napi, skb, 1);
 671                 break;
 672
 673         case GRO_MERGED_FREE:
 674                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 675                         napi_skb_free_stolen_head(skb);
 676                 else
 677                         napi_reuse_skb(napi, skb);
 678                 break;
 679
 680         case GRO_MERGED:
 681         case GRO_CONSUMED:
 682                 break;
 683         }
 684
 685         return ret;
 686 }
 687
 688 /* Upper GRO stack assumes network header starts at gro_offset=0
 689  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 690  * We copy ethernet header into skb->data to have a common layout.
 691  */
 692 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 693 {
 694         struct sk_buff *skb = napi->skb;
 695         const struct ethhdr *eth;
 696         unsigned int hlen = sizeof(*eth);
 697
 698         napi->skb = NULL;
 699
 700         skb_reset_mac_header(skb);
 701         skb_gro_reset_offset(skb, hlen);
 702
 703         if (unlikely(skb_gro_header_hard(skb, hlen))) {
 704                 eth = skb_gro_header_slow(skb, hlen, 0);
 705                 if (unlikely(!eth)) {
 706                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 707                                              __func__, napi->dev->name);
 708                         napi_reuse_skb(napi, skb);
 709                         return NULL;
 710                 }
 711         } else {
 712                 eth = (const struct ethhdr *)skb->data;
 713                 gro_pull_from_frag0(skb, hlen);
 714                 NAPI_GRO_CB(skb)->frag0 += hlen;
 715                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 716         }
 717         __skb_pull(skb, hlen);
 718
 719         /*
 720          * This works because the only protocols we care about don't require
 721          * special handling.
 722          * We'll fix it up properly in napi_frags_finish()
 723          */
 724         skb->protocol = eth->h_proto;
 725
 726         return skb;
 727 }
 728
 729 gro_result_t napi_gro_frags(struct napi_struct *napi)
 730 {
 731         gro_result_t ret;
 732         struct sk_buff *skb = napi_frags_skb(napi);
 733
 734         trace_napi_gro_frags_entry(skb);
 735
 736         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 737         trace_napi_gro_frags_exit(ret);
 738
 739         return ret;
 740 }
 741 EXPORT_SYMBOL(napi_gro_frags);
 742
 743 /* Compute the checksum from gro_offset and return the folded value
 744  * after adding in any pseudo checksum.
 745  */
 746 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 747 {
 748         __wsum wsum;
 749         __sum16 sum;
 750
 751         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 752
 753         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 754         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 755         /* See comments in __skb_checksum_complete(). */
 756         if (likely(!sum)) {
 757                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 758                     !skb->csum_complete_sw)
 759                         netdev_rx_csum_fault(skb->dev, skb);
 760         }
 761
 762         NAPI_GRO_CB(skb)->csum = wsum;
 763         NAPI_GRO_CB(skb)->csum_valid = 1;
 764
 765         return sum;
 766 }
 767 EXPORT_SYMBOL(__skb_gro_checksum_complete);