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
  14 /**
  15  *      dev_add_offload - register offload handlers
  16  *      @po: protocol offload declaration
  17  *
  18  *      Add protocol offload handlers to the networking stack. The passed
  19  *      &proto_offload is linked into kernel lists and may not be freed until
  20  *      it has been removed from the kernel lists.
  21  *
  22  *      This call does not sleep therefore it can not
  23  *      guarantee all CPU's that are in middle of receiving packets
  24  *      will see the new offload handlers (until the next received packet).
  25  */
  26 void dev_add_offload(struct packet_offload *po)
  27 {
  28         struct packet_offload *elem;
  29
  30         spin_lock(&offload_lock);
  31         list_for_each_entry(elem, &net_hotdata.offload_base, list) {
  32                 if (po->priority < elem->priority)
  33                         break;
  34         }
  35         list_add_rcu(&po->list, elem->list.prev);
  36         spin_unlock(&offload_lock);
  37 }
  38 EXPORT_SYMBOL(dev_add_offload);
  39
  40 /**
  41  *      __dev_remove_offload     - remove offload handler
  42  *      @po: packet offload declaration
  43  *
  44  *      Remove a protocol offload handler that was previously added to the
  45  *      kernel offload handlers by dev_add_offload(). The passed &offload_type
  46  *      is removed from the kernel lists and can be freed or reused once this
  47  *      function returns.
  48  *
  49  *      The packet type might still be in use by receivers
  50  *      and must not be freed until after all the CPU's have gone
  51  *      through a quiescent state.
  52  */
  53 static void __dev_remove_offload(struct packet_offload *po)
  54 {
  55         struct list_head *head = &net_hotdata.offload_base;
  56         struct packet_offload *po1;
  57
  58         spin_lock(&offload_lock);
  59
  60         list_for_each_entry(po1, head, list) {
  61                 if (po == po1) {
  62                         list_del_rcu(&po->list);
  63                         goto out;
  64                 }
  65         }
  66
  67         pr_warn("dev_remove_offload: %p not found\n", po);
  68 out:
  69         spin_unlock(&offload_lock);
  70 }
  71
  72 /**
  73  *      dev_remove_offload       - remove packet offload handler
  74  *      @po: packet offload declaration
  75  *
  76  *      Remove a packet offload handler that was previously added to the kernel
  77  *      offload handlers by dev_add_offload(). The passed &offload_type is
  78  *      removed from the kernel lists and can be freed or reused once this
  79  *      function returns.
  80  *
  81  *      This call sleeps to guarantee that no CPU is looking at the packet
  82  *      type after return.
  83  */
  84 void dev_remove_offload(struct packet_offload *po)
  85 {
  86         __dev_remove_offload(po);
  87
  88         synchronize_net();
  89 }
  90 EXPORT_SYMBOL(dev_remove_offload);
  91
  92
  93 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
  94 {
  95         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
  96         unsigned int offset = skb_gro_offset(skb);
  97         unsigned int headlen = skb_headlen(skb);
  98         unsigned int len = skb_gro_len(skb);
  99         unsigned int delta_truesize;
 100         unsigned int gro_max_size;
 101         unsigned int new_truesize;
 102         struct sk_buff *lp;
 103         int segs;
 104
 105         /* Do not splice page pool based packets w/ non-page pool
 106          * packets. This can result in reference count issues as page
 107          * pool pages will not decrement the reference count and will
 108          * instead be immediately returned to the pool or have frag
 109          * count decremented.
 110          */
 111         if (p->pp_recycle != skb->pp_recycle)
 112                 return -ETOOMANYREFS;
 113
 114         /* pairs with WRITE_ONCE() in netif_set_gro(_ipv4)_max_size() */
 115         gro_max_size = p->protocol == htons(ETH_P_IPV6) ?
 116                         READ_ONCE(p->dev->gro_max_size) :
 117                         READ_ONCE(p->dev->gro_ipv4_max_size);
 118
 119         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 120                 return -E2BIG;
 121
 122         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 123                 if (NAPI_GRO_CB(skb)->proto != IPPROTO_TCP ||
 124                     (p->protocol == htons(ETH_P_IPV6) &&
 125                      skb_headroom(p) < sizeof(struct hop_jumbo_hdr)) ||
 126                     p->encapsulation)
 127                         return -E2BIG;
 128         }
 129
 130         segs = NAPI_GRO_CB(skb)->count;
 131         lp = NAPI_GRO_CB(p)->last;
 132         pinfo = skb_shinfo(lp);
 133
 134         if (headlen <= offset) {
 135                 skb_frag_t *frag;
 136                 skb_frag_t *frag2;
 137                 int i = skbinfo->nr_frags;
 138                 int nr_frags = pinfo->nr_frags + i;
 139
 140                 if (nr_frags > MAX_SKB_FRAGS)
 141                         goto merge;
 142
 143                 offset -= headlen;
 144                 pinfo->nr_frags = nr_frags;
 145                 skbinfo->nr_frags = 0;
 146
 147                 frag = pinfo->frags + nr_frags;
 148                 frag2 = skbinfo->frags + i;
 149                 do {
 150                         *--frag = *--frag2;
 151                 } while (--i);
 152
 153                 skb_frag_off_add(frag, offset);
 154                 skb_frag_size_sub(frag, offset);
 155
 156                 /* all fragments truesize : remove (head size + sk_buff) */
 157                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 158                 delta_truesize = skb->truesize - new_truesize;
 159
 160                 skb->truesize = new_truesize;
 161                 skb->len -= skb->data_len;
 162                 skb->data_len = 0;
 163
 164                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 165                 goto done;
 166         } else if (skb->head_frag) {
 167                 int nr_frags = pinfo->nr_frags;
 168                 skb_frag_t *frag = pinfo->frags + nr_frags;
 169                 struct page *page = virt_to_head_page(skb->head);
 170                 unsigned int first_size = headlen - offset;
 171                 unsigned int first_offset;
 172
 173                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 174                         goto merge;
 175
 176                 first_offset = skb->data -
 177                                (unsigned char *)page_address(page) +
 178                                offset;
 179
 180                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 181
 182                 skb_frag_fill_page_desc(frag, page, first_offset, first_size);
 183
 184                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 185                 /* We dont need to clear skbinfo->nr_frags here */
 186
 187                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 188                 delta_truesize = skb->truesize - new_truesize;
 189                 skb->truesize = new_truesize;
 190                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 191                 goto done;
 192         }
 193
 194 merge:
 195         /* sk ownership - if any - completely transferred to the aggregated packet */
 196         skb->destructor = NULL;
 197         skb->sk = NULL;
 198         delta_truesize = skb->truesize;
 199         if (offset > headlen) {
 200                 unsigned int eat = offset - headlen;
 201
 202                 skb_frag_off_add(&skbinfo->frags[0], eat);
 203                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 204                 skb->data_len -= eat;
 205                 skb->len -= eat;
 206                 offset = headlen;
 207         }
 208
 209         __skb_pull(skb, offset);
 210
 211         if (NAPI_GRO_CB(p)->last == p)
 212                 skb_shinfo(p)->frag_list = skb;
 213         else
 214                 NAPI_GRO_CB(p)->last->next = skb;
 215         NAPI_GRO_CB(p)->last = skb;
 216         __skb_header_release(skb);
 217         lp = p;
 218
 219 done:
 220         NAPI_GRO_CB(p)->count += segs;
 221         p->data_len += len;
 222         p->truesize += delta_truesize;
 223         p->len += len;
 224         if (lp != p) {
 225                 lp->data_len += len;
 226                 lp->truesize += delta_truesize;
 227                 lp->len += len;
 228         }
 229         NAPI_GRO_CB(skb)->same_flow = 1;
 230         return 0;
 231 }
 232
 233
 234 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 235 {
 236         struct list_head *head = &net_hotdata.offload_base;
 237         struct packet_offload *ptype;
 238         __be16 type = skb->protocol;
 239         int err = -ENOENT;
 240
 241         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 242
 243         if (NAPI_GRO_CB(skb)->count == 1) {
 244                 skb_shinfo(skb)->gso_size = 0;
 245                 goto out;
 246         }
 247
 248         rcu_read_lock();
 249         list_for_each_entry_rcu(ptype, head, list) {
 250                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 251                         continue;
 252
 253                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 254                                          ipv6_gro_complete, inet_gro_complete,
 255                                          skb, 0);
 256                 break;
 257         }
 258         rcu_read_unlock();
 259
 260         if (err) {
 261                 WARN_ON(&ptype->list == head);
 262                 kfree_skb(skb);
 263                 return;
 264         }
 265
 266 out:
 267         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 268 }
 269
 270 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 271                                    bool flush_old)
 272 {
 273         struct list_head *head = &napi->gro_hash[index].list;
 274         struct sk_buff *skb, *p;
 275
 276         list_for_each_entry_safe_reverse(skb, p, head, list) {
 277                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 278                         return;
 279                 skb_list_del_init(skb);
 280                 napi_gro_complete(napi, skb);
 281                 napi->gro_hash[index].count--;
 282         }
 283
 284         if (!napi->gro_hash[index].count)
 285                 __clear_bit(index, &napi->gro_bitmask);
 286 }
 287
 288 /* napi->gro_hash[].list contains packets ordered by age.
 289  * youngest packets at the head of it.
 290  * Complete skbs in reverse order to reduce latencies.
 291  */
 292 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 293 {
 294         unsigned long bitmask = napi->gro_bitmask;
 295         unsigned int i, base = ~0U;
 296
 297         while ((i = ffs(bitmask)) != 0) {
 298                 bitmask >>= i;
 299                 base += i;
 300                 __napi_gro_flush_chain(napi, base, flush_old);
 301         }
 302 }
 303 EXPORT_SYMBOL(napi_gro_flush);
 304
 305 static unsigned long gro_list_prepare_tc_ext(const struct sk_buff *skb,
 306                                              const struct sk_buff *p,
 307                                              unsigned long diffs)
 308 {
 309 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 310         struct tc_skb_ext *skb_ext;
 311         struct tc_skb_ext *p_ext;
 312
 313         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 314         p_ext = skb_ext_find(p, TC_SKB_EXT);
 315
 316         diffs |= (!!p_ext) ^ (!!skb_ext);
 317         if (!diffs && unlikely(skb_ext))
 318                 diffs |= p_ext->chain ^ skb_ext->chain;
 319 #endif
 320         return diffs;
 321 }
 322
 323 static void gro_list_prepare(const struct list_head *head,
 324                              const struct sk_buff *skb)
 325 {
 326         unsigned int maclen = skb->dev->hard_header_len;
 327         u32 hash = skb_get_hash_raw(skb);
 328         struct sk_buff *p;
 329
 330         list_for_each_entry(p, head, list) {
 331                 unsigned long diffs;
 332
 333                 NAPI_GRO_CB(p)->flush = 0;
 334
 335                 if (hash != skb_get_hash_raw(p)) {
 336                         NAPI_GRO_CB(p)->same_flow = 0;
 337                         continue;
 338                 }
 339
 340                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 341                 diffs |= p->vlan_all ^ skb->vlan_all;
 342                 diffs |= skb_metadata_differs(p, skb);
 343                 if (maclen == ETH_HLEN)
 344                         diffs |= compare_ether_header(skb_mac_header(p),
 345                                                       skb_mac_header(skb));
 346                 else if (!diffs)
 347                         diffs = memcmp(skb_mac_header(p),
 348                                        skb_mac_header(skb),
 349                                        maclen);
 350
 351                 /* in most common scenarions 'slow_gro' is 0
 352                  * otherwise we are already on some slower paths
 353                  * either skip all the infrequent tests altogether or
 354                  * avoid trying too hard to skip each of them individually
 355                  */
 356                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 357                         diffs |= p->sk != skb->sk;
 358                         diffs |= skb_metadata_dst_cmp(p, skb);
 359                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 360
 361                         diffs |= gro_list_prepare_tc_ext(skb, p, diffs);
 362                 }
 363
 364                 NAPI_GRO_CB(p)->same_flow = !diffs;
 365         }
 366 }
 367
 368 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 369 {
 370         const struct skb_shared_info *pinfo;
 371         const skb_frag_t *frag0;
 372         unsigned int headlen;
 373
 374         NAPI_GRO_CB(skb)->network_offset = 0;
 375         NAPI_GRO_CB(skb)->data_offset = 0;
 376         headlen = skb_headlen(skb);
 377         NAPI_GRO_CB(skb)->frag0 = skb->data;
 378         NAPI_GRO_CB(skb)->frag0_len = headlen;
 379         if (headlen)
 380                 return;
 381
 382         pinfo = skb_shinfo(skb);
 383         frag0 = &pinfo->frags[0];
 384
 385         if (pinfo->nr_frags && !PageHighMem(skb_frag_page(frag0)) &&
 386             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 387                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 388                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 389                                                     skb_frag_size(frag0),
 390                                                     skb->end - skb->tail);
 391         }
 392 }
 393
 394 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 395 {
 396         struct skb_shared_info *pinfo = skb_shinfo(skb);
 397
 398         BUG_ON(skb->end - skb->tail < grow);
 399
 400         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 401
 402         skb->data_len -= grow;
 403         skb->tail += grow;
 404
 405         skb_frag_off_add(&pinfo->frags[0], grow);
 406         skb_frag_size_sub(&pinfo->frags[0], grow);
 407
 408         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 409                 skb_frag_unref(skb, 0);
 410                 memmove(pinfo->frags, pinfo->frags + 1,
 411                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 412         }
 413 }
 414
 415 static void gro_try_pull_from_frag0(struct sk_buff *skb)
 416 {
 417         int grow = skb_gro_offset(skb) - skb_headlen(skb);
 418
 419         if (grow > 0)
 420                 gro_pull_from_frag0(skb, grow);
 421 }
 422
 423 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 424 {
 425         struct sk_buff *oldest;
 426
 427         oldest = list_last_entry(head, struct sk_buff, list);
 428
 429         /* We are called with head length >= MAX_GRO_SKBS, so this is
 430          * impossible.
 431          */
 432         if (WARN_ON_ONCE(!oldest))
 433                 return;
 434
 435         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 436          * SKB to the chain.
 437          */
 438         skb_list_del_init(oldest);
 439         napi_gro_complete(napi, oldest);
 440 }
 441
 442 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 443 {
 444         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 445         struct gro_list *gro_list = &napi->gro_hash[bucket];
 446         struct list_head *head = &net_hotdata.offload_base;
 447         struct packet_offload *ptype;
 448         __be16 type = skb->protocol;
 449         struct sk_buff *pp = NULL;
 450         enum gro_result ret;
 451         int same_flow;
 452
 453         if (netif_elide_gro(skb->dev))
 454                 goto normal;
 455
 456         gro_list_prepare(&gro_list->list, skb);
 457
 458         rcu_read_lock();
 459         list_for_each_entry_rcu(ptype, head, list) {
 460                 if (ptype->type == type && ptype->callbacks.gro_receive)
 461                         goto found_ptype;
 462         }
 463         rcu_read_unlock();
 464         goto normal;
 465
 466 found_ptype:
 467         skb_set_network_header(skb, skb_gro_offset(skb));
 468         skb_reset_mac_len(skb);
 469         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 470         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 471                                         sizeof(u32))); /* Avoid slow unaligned acc */
 472         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 473         NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 474         NAPI_GRO_CB(skb)->is_atomic = 1;
 475         NAPI_GRO_CB(skb)->count = 1;
 476         if (unlikely(skb_is_gso(skb))) {
 477                 NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 478                 /* Only support TCP and non DODGY users. */
 479                 if (!skb_is_gso_tcp(skb) ||
 480                     (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 481                         NAPI_GRO_CB(skb)->flush = 1;
 482         }
 483
 484         /* Setup for GRO checksum validation */
 485         switch (skb->ip_summed) {
 486         case CHECKSUM_COMPLETE:
 487                 NAPI_GRO_CB(skb)->csum = skb->csum;
 488                 NAPI_GRO_CB(skb)->csum_valid = 1;
 489                 break;
 490         case CHECKSUM_UNNECESSARY:
 491                 NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 492                 break;
 493         }
 494
 495         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 496                                 ipv6_gro_receive, inet_gro_receive,
 497                                 &gro_list->list, skb);
 498
 499         rcu_read_unlock();
 500
 501         if (PTR_ERR(pp) == -EINPROGRESS) {
 502                 ret = GRO_CONSUMED;
 503                 goto ok;
 504         }
 505
 506         same_flow = NAPI_GRO_CB(skb)->same_flow;
 507         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 508
 509         if (pp) {
 510                 skb_list_del_init(pp);
 511                 napi_gro_complete(napi, pp);
 512                 gro_list->count--;
 513         }
 514
 515         if (same_flow)
 516                 goto ok;
 517
 518         if (NAPI_GRO_CB(skb)->flush)
 519                 goto normal;
 520
 521         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 522                 gro_flush_oldest(napi, &gro_list->list);
 523         else
 524                 gro_list->count++;
 525
 526         /* Must be called before setting NAPI_GRO_CB(skb)->{age|last} */
 527         gro_try_pull_from_frag0(skb);
 528         NAPI_GRO_CB(skb)->age = jiffies;
 529         NAPI_GRO_CB(skb)->last = skb;
 530         if (!skb_is_gso(skb))
 531                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 532         list_add(&skb->list, &gro_list->list);
 533         ret = GRO_HELD;
 534 ok:
 535         if (gro_list->count) {
 536                 if (!test_bit(bucket, &napi->gro_bitmask))
 537                         __set_bit(bucket, &napi->gro_bitmask);
 538         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 539                 __clear_bit(bucket, &napi->gro_bitmask);
 540         }
 541
 542         return ret;
 543
 544 normal:
 545         ret = GRO_NORMAL;
 546         gro_try_pull_from_frag0(skb);
 547         goto ok;
 548 }
 549
 550 struct packet_offload *gro_find_receive_by_type(__be16 type)
 551 {
 552         struct list_head *offload_head = &net_hotdata.offload_base;
 553         struct packet_offload *ptype;
 554
 555         list_for_each_entry_rcu(ptype, offload_head, list) {
 556                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 557                         continue;
 558                 return ptype;
 559         }
 560         return NULL;
 561 }
 562 EXPORT_SYMBOL(gro_find_receive_by_type);
 563
 564 struct packet_offload *gro_find_complete_by_type(__be16 type)
 565 {
 566         struct list_head *offload_head = &net_hotdata.offload_base;
 567         struct packet_offload *ptype;
 568
 569         list_for_each_entry_rcu(ptype, offload_head, list) {
 570                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 571                         continue;
 572                 return ptype;
 573         }
 574         return NULL;
 575 }
 576 EXPORT_SYMBOL(gro_find_complete_by_type);
 577
 578 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 579                                     struct sk_buff *skb,
 580                                     gro_result_t ret)
 581 {
 582         switch (ret) {
 583         case GRO_NORMAL:
 584                 gro_normal_one(napi, skb, 1);
 585                 break;
 586
 587         case GRO_MERGED_FREE:
 588                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 589                         napi_skb_free_stolen_head(skb);
 590                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 591                         __kfree_skb(skb);
 592                 else
 593                         __napi_kfree_skb(skb, SKB_CONSUMED);
 594                 break;
 595
 596         case GRO_HELD:
 597         case GRO_MERGED:
 598         case GRO_CONSUMED:
 599                 break;
 600         }
 601
 602         return ret;
 603 }
 604
 605 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 606 {
 607         gro_result_t ret;
 608
 609         skb_mark_napi_id(skb, napi);
 610         trace_napi_gro_receive_entry(skb);
 611
 612         skb_gro_reset_offset(skb, 0);
 613
 614         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 615         trace_napi_gro_receive_exit(ret);
 616
 617         return ret;
 618 }
 619 EXPORT_SYMBOL(napi_gro_receive);
 620
 621 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 622 {
 623         if (unlikely(skb->pfmemalloc)) {
 624                 consume_skb(skb);
 625                 return;
 626         }
 627         __skb_pull(skb, skb_headlen(skb));
 628         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 629         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 630         __vlan_hwaccel_clear_tag(skb);
 631         skb->dev = napi->dev;
 632         skb->skb_iif = 0;
 633
 634         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 635         skb->pkt_type = PACKET_HOST;
 636
 637         skb->encapsulation = 0;
 638         skb_shinfo(skb)->gso_type = 0;
 639         skb_shinfo(skb)->gso_size = 0;
 640         if (unlikely(skb->slow_gro)) {
 641                 skb_orphan(skb);
 642                 skb_ext_reset(skb);
 643                 nf_reset_ct(skb);
 644                 skb->slow_gro = 0;
 645         }
 646
 647         napi->skb = skb;
 648 }
 649
 650 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 651 {
 652         struct sk_buff *skb = napi->skb;
 653
 654         if (!skb) {
 655                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 656                 if (skb) {
 657                         napi->skb = skb;
 658                         skb_mark_napi_id(skb, napi);
 659                 }
 660         }
 661         return skb;
 662 }
 663 EXPORT_SYMBOL(napi_get_frags);
 664
 665 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 666                                       struct sk_buff *skb,
 667                                       gro_result_t ret)
 668 {
 669         switch (ret) {
 670         case GRO_NORMAL:
 671         case GRO_HELD:
 672                 __skb_push(skb, ETH_HLEN);
 673                 skb->protocol = eth_type_trans(skb, skb->dev);
 674                 if (ret == GRO_NORMAL)
 675                         gro_normal_one(napi, skb, 1);
 676                 break;
 677
 678         case GRO_MERGED_FREE:
 679                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 680                         napi_skb_free_stolen_head(skb);
 681                 else
 682                         napi_reuse_skb(napi, skb);
 683                 break;
 684
 685         case GRO_MERGED:
 686         case GRO_CONSUMED:
 687                 break;
 688         }
 689
 690         return ret;
 691 }
 692
 693 /* Upper GRO stack assumes network header starts at gro_offset=0
 694  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 695  * We copy ethernet header into skb->data to have a common layout.
 696  */
 697 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 698 {
 699         struct sk_buff *skb = napi->skb;
 700         const struct ethhdr *eth;
 701         unsigned int hlen = sizeof(*eth);
 702
 703         napi->skb = NULL;
 704
 705         skb_reset_mac_header(skb);
 706         skb_gro_reset_offset(skb, hlen);
 707
 708         if (unlikely(!skb_gro_may_pull(skb, hlen))) {
 709                 eth = skb_gro_header_slow(skb, hlen, 0);
 710                 if (unlikely(!eth)) {
 711                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 712                                              __func__, napi->dev->name);
 713                         napi_reuse_skb(napi, skb);
 714                         return NULL;
 715                 }
 716         } else {
 717                 eth = (const struct ethhdr *)skb->data;
 718
 719                 if (NAPI_GRO_CB(skb)->frag0 != skb->data)
 720                         gro_pull_from_frag0(skb, hlen);
 721
 722                 NAPI_GRO_CB(skb)->frag0 += hlen;
 723                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 724         }
 725         __skb_pull(skb, hlen);
 726
 727         /*
 728          * This works because the only protocols we care about don't require
 729          * special handling.
 730          * We'll fix it up properly in napi_frags_finish()
 731          */
 732         skb->protocol = eth->h_proto;
 733
 734         return skb;
 735 }
 736
 737 gro_result_t napi_gro_frags(struct napi_struct *napi)
 738 {
 739         gro_result_t ret;
 740         struct sk_buff *skb = napi_frags_skb(napi);
 741
 742         trace_napi_gro_frags_entry(skb);
 743
 744         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 745         trace_napi_gro_frags_exit(ret);
 746
 747         return ret;
 748 }
 749 EXPORT_SYMBOL(napi_gro_frags);
 750
 751 /* Compute the checksum from gro_offset and return the folded value
 752  * after adding in any pseudo checksum.
 753  */
 754 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 755 {
 756         __wsum wsum;
 757         __sum16 sum;
 758
 759         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 760
 761         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 762         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 763         /* See comments in __skb_checksum_complete(). */
 764         if (likely(!sum)) {
 765                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 766                     !skb->csum_complete_sw)
 767                         netdev_rx_csum_fault(skb->dev, skb);
 768         }
 769
 770         NAPI_GRO_CB(skb)->csum = wsum;
 771         NAPI_GRO_CB(skb)->csum_valid = 1;
 772
 773         return sum;
 774 }
 775 EXPORT_SYMBOL(__skb_gro_checksum_complete);