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 #include <linux/skbuff_ref.h>
   7
   8 #define MAX_GRO_SKBS 8
   9
  10 /* This should be increased if a protocol with a bigger head is added. */
  11 #define GRO_MAX_HEAD (MAX_HEADER + 128)
  12
  13 static DEFINE_SPINLOCK(offload_lock);
  14
  15 /**
  16  *      dev_add_offload - register offload handlers
  17  *      @po: protocol offload declaration
  18  *
  19  *      Add protocol offload handlers to the networking stack. The passed
  20  *      &proto_offload is linked into kernel lists and may not be freed until
  21  *      it has been removed from the kernel lists.
  22  *
  23  *      This call does not sleep therefore it can not
  24  *      guarantee all CPU's that are in middle of receiving packets
  25  *      will see the new offload handlers (until the next received packet).
  26  */
  27 void dev_add_offload(struct packet_offload *po)
  28 {
  29         struct packet_offload *elem;
  30
  31         spin_lock(&offload_lock);
  32         list_for_each_entry(elem, &net_hotdata.offload_base, list) {
  33                 if (po->priority < elem->priority)
  34                         break;
  35         }
  36         list_add_rcu(&po->list, elem->list.prev);
  37         spin_unlock(&offload_lock);
  38 }
  39 EXPORT_SYMBOL(dev_add_offload);
  40
  41 /**
  42  *      __dev_remove_offload     - remove offload handler
  43  *      @po: packet offload declaration
  44  *
  45  *      Remove a protocol offload handler that was previously added to the
  46  *      kernel offload handlers by dev_add_offload(). The passed &offload_type
  47  *      is removed from the kernel lists and can be freed or reused once this
  48  *      function returns.
  49  *
  50  *      The packet type might still be in use by receivers
  51  *      and must not be freed until after all the CPU's have gone
  52  *      through a quiescent state.
  53  */
  54 static void __dev_remove_offload(struct packet_offload *po)
  55 {
  56         struct list_head *head = &net_hotdata.offload_base;
  57         struct packet_offload *po1;
  58
  59         spin_lock(&offload_lock);
  60
  61         list_for_each_entry(po1, head, list) {
  62                 if (po == po1) {
  63                         list_del_rcu(&po->list);
  64                         goto out;
  65                 }
  66         }
  67
  68         pr_warn("dev_remove_offload: %p not found\n", po);
  69 out:
  70         spin_unlock(&offload_lock);
  71 }
  72
  73 /**
  74  *      dev_remove_offload       - remove packet offload handler
  75  *      @po: packet offload declaration
  76  *
  77  *      Remove a packet offload handler that was previously added to the kernel
  78  *      offload handlers by dev_add_offload(). The passed &offload_type is
  79  *      removed from the kernel lists and can be freed or reused once this
  80  *      function returns.
  81  *
  82  *      This call sleeps to guarantee that no CPU is looking at the packet
  83  *      type after return.
  84  */
  85 void dev_remove_offload(struct packet_offload *po)
  86 {
  87         __dev_remove_offload(po);
  88
  89         synchronize_net();
  90 }
  91 EXPORT_SYMBOL(dev_remove_offload);
  92
  93
  94 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
  95 {
  96         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
  97         unsigned int offset = skb_gro_offset(skb);
  98         unsigned int headlen = skb_headlen(skb);
  99         unsigned int len = skb_gro_len(skb);
 100         unsigned int delta_truesize;
 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         if (unlikely(p->len + len >= netif_get_gro_max_size(p->dev, p) ||
 115                      NAPI_GRO_CB(skb)->flush))
 116                 return -E2BIG;
 117
 118         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 119                 if (NAPI_GRO_CB(skb)->proto != IPPROTO_TCP ||
 120                     (p->protocol == htons(ETH_P_IPV6) &&
 121                      skb_headroom(p) < sizeof(struct hop_jumbo_hdr)) ||
 122                     p->encapsulation)
 123                         return -E2BIG;
 124         }
 125
 126         segs = NAPI_GRO_CB(skb)->count;
 127         lp = NAPI_GRO_CB(p)->last;
 128         pinfo = skb_shinfo(lp);
 129
 130         if (headlen <= offset) {
 131                 skb_frag_t *frag;
 132                 skb_frag_t *frag2;
 133                 int i = skbinfo->nr_frags;
 134                 int nr_frags = pinfo->nr_frags + i;
 135
 136                 if (nr_frags > MAX_SKB_FRAGS)
 137                         goto merge;
 138
 139                 offset -= headlen;
 140                 pinfo->nr_frags = nr_frags;
 141                 skbinfo->nr_frags = 0;
 142
 143                 frag = pinfo->frags + nr_frags;
 144                 frag2 = skbinfo->frags + i;
 145                 do {
 146                         *--frag = *--frag2;
 147                 } while (--i);
 148
 149                 skb_frag_off_add(frag, offset);
 150                 skb_frag_size_sub(frag, offset);
 151
 152                 /* all fragments truesize : remove (head size + sk_buff) */
 153                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 154                 delta_truesize = skb->truesize - new_truesize;
 155
 156                 skb->truesize = new_truesize;
 157                 skb->len -= skb->data_len;
 158                 skb->data_len = 0;
 159
 160                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 161                 goto done;
 162         } else if (skb->head_frag) {
 163                 int nr_frags = pinfo->nr_frags;
 164                 skb_frag_t *frag = pinfo->frags + nr_frags;
 165                 struct page *page = virt_to_head_page(skb->head);
 166                 unsigned int first_size = headlen - offset;
 167                 unsigned int first_offset;
 168
 169                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 170                         goto merge;
 171
 172                 first_offset = skb->data -
 173                                (unsigned char *)page_address(page) +
 174                                offset;
 175
 176                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 177
 178                 skb_frag_fill_page_desc(frag, page, first_offset, first_size);
 179
 180                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 181                 /* We dont need to clear skbinfo->nr_frags here */
 182
 183                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 184                 delta_truesize = skb->truesize - new_truesize;
 185                 skb->truesize = new_truesize;
 186                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 187                 goto done;
 188         }
 189
 190 merge:
 191         /* sk ownership - if any - completely transferred to the aggregated packet */
 192         skb->destructor = NULL;
 193         skb->sk = NULL;
 194         delta_truesize = skb->truesize;
 195         if (offset > headlen) {
 196                 unsigned int eat = offset - headlen;
 197
 198                 skb_frag_off_add(&skbinfo->frags[0], eat);
 199                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 200                 skb->data_len -= eat;
 201                 skb->len -= eat;
 202                 offset = headlen;
 203         }
 204
 205         __skb_pull(skb, offset);
 206
 207         if (NAPI_GRO_CB(p)->last == p)
 208                 skb_shinfo(p)->frag_list = skb;
 209         else
 210                 NAPI_GRO_CB(p)->last->next = skb;
 211         NAPI_GRO_CB(p)->last = skb;
 212         __skb_header_release(skb);
 213         lp = p;
 214
 215 done:
 216         NAPI_GRO_CB(p)->count += segs;
 217         p->data_len += len;
 218         p->truesize += delta_truesize;
 219         p->len += len;
 220         if (lp != p) {
 221                 lp->data_len += len;
 222                 lp->truesize += delta_truesize;
 223                 lp->len += len;
 224         }
 225         NAPI_GRO_CB(skb)->same_flow = 1;
 226         return 0;
 227 }
 228
 229 int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
 230 {
 231         if (unlikely(p->len + skb->len >= 65536))
 232                 return -E2BIG;
 233
 234         if (NAPI_GRO_CB(p)->last == p)
 235                 skb_shinfo(p)->frag_list = skb;
 236         else
 237                 NAPI_GRO_CB(p)->last->next = skb;
 238
 239         skb_pull(skb, skb_gro_offset(skb));
 240
 241         NAPI_GRO_CB(p)->last = skb;
 242         NAPI_GRO_CB(p)->count++;
 243         p->data_len += skb->len;
 244
 245         /* sk ownership - if any - completely transferred to the aggregated packet */
 246         skb->destructor = NULL;
 247         skb->sk = NULL;
 248         p->truesize += skb->truesize;
 249         p->len += skb->len;
 250
 251         NAPI_GRO_CB(skb)->same_flow = 1;
 252
 253         return 0;
 254 }
 255
 256
 257 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 258 {
 259         struct list_head *head = &net_hotdata.offload_base;
 260         struct packet_offload *ptype;
 261         __be16 type = skb->protocol;
 262         int err = -ENOENT;
 263
 264         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 265
 266         if (NAPI_GRO_CB(skb)->count == 1) {
 267                 skb_shinfo(skb)->gso_size = 0;
 268                 goto out;
 269         }
 270
 271         rcu_read_lock();
 272         list_for_each_entry_rcu(ptype, head, list) {
 273                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 274                         continue;
 275
 276                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 277                                          ipv6_gro_complete, inet_gro_complete,
 278                                          skb, 0);
 279                 break;
 280         }
 281         rcu_read_unlock();
 282
 283         if (err) {
 284                 WARN_ON(&ptype->list == head);
 285                 kfree_skb(skb);
 286                 return;
 287         }
 288
 289 out:
 290         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 291 }
 292
 293 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 294                                    bool flush_old)
 295 {
 296         struct list_head *head = &napi->gro_hash[index].list;
 297         struct sk_buff *skb, *p;
 298
 299         list_for_each_entry_safe_reverse(skb, p, head, list) {
 300                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 301                         return;
 302                 skb_list_del_init(skb);
 303                 napi_gro_complete(napi, skb);
 304                 napi->gro_hash[index].count--;
 305         }
 306
 307         if (!napi->gro_hash[index].count)
 308                 __clear_bit(index, &napi->gro_bitmask);
 309 }
 310
 311 /* napi->gro_hash[].list contains packets ordered by age.
 312  * youngest packets at the head of it.
 313  * Complete skbs in reverse order to reduce latencies.
 314  */
 315 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 316 {
 317         unsigned long bitmask = napi->gro_bitmask;
 318         unsigned int i, base = ~0U;
 319
 320         while ((i = ffs(bitmask)) != 0) {
 321                 bitmask >>= i;
 322                 base += i;
 323                 __napi_gro_flush_chain(napi, base, flush_old);
 324         }
 325 }
 326 EXPORT_SYMBOL(napi_gro_flush);
 327
 328 static unsigned long gro_list_prepare_tc_ext(const struct sk_buff *skb,
 329                                              const struct sk_buff *p,
 330                                              unsigned long diffs)
 331 {
 332 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 333         struct tc_skb_ext *skb_ext;
 334         struct tc_skb_ext *p_ext;
 335
 336         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 337         p_ext = skb_ext_find(p, TC_SKB_EXT);
 338
 339         diffs |= (!!p_ext) ^ (!!skb_ext);
 340         if (!diffs && unlikely(skb_ext))
 341                 diffs |= p_ext->chain ^ skb_ext->chain;
 342 #endif
 343         return diffs;
 344 }
 345
 346 static void gro_list_prepare(const struct list_head *head,
 347                              const struct sk_buff *skb)
 348 {
 349         unsigned int maclen = skb->dev->hard_header_len;
 350         u32 hash = skb_get_hash_raw(skb);
 351         struct sk_buff *p;
 352
 353         list_for_each_entry(p, head, list) {
 354                 unsigned long diffs;
 355
 356                 if (hash != skb_get_hash_raw(p)) {
 357                         NAPI_GRO_CB(p)->same_flow = 0;
 358                         continue;
 359                 }
 360
 361                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 362                 diffs |= p->vlan_all ^ skb->vlan_all;
 363                 diffs |= skb_metadata_differs(p, skb);
 364                 if (maclen == ETH_HLEN)
 365                         diffs |= compare_ether_header(skb_mac_header(p),
 366                                                       skb_mac_header(skb));
 367                 else if (!diffs)
 368                         diffs = memcmp(skb_mac_header(p),
 369                                        skb_mac_header(skb),
 370                                        maclen);
 371
 372                 /* in most common scenarios 'slow_gro' is 0
 373                  * otherwise we are already on some slower paths
 374                  * either skip all the infrequent tests altogether or
 375                  * avoid trying too hard to skip each of them individually
 376                  */
 377                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 378                         diffs |= p->sk != skb->sk;
 379                         diffs |= skb_metadata_dst_cmp(p, skb);
 380                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 381
 382                         diffs |= gro_list_prepare_tc_ext(skb, p, diffs);
 383                 }
 384
 385                 NAPI_GRO_CB(p)->same_flow = !diffs;
 386         }
 387 }
 388
 389 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 390 {
 391         const struct skb_shared_info *pinfo;
 392         const skb_frag_t *frag0;
 393         unsigned int headlen;
 394
 395         NAPI_GRO_CB(skb)->network_offset = 0;
 396         NAPI_GRO_CB(skb)->data_offset = 0;
 397         headlen = skb_headlen(skb);
 398         NAPI_GRO_CB(skb)->frag0 = skb->data;
 399         NAPI_GRO_CB(skb)->frag0_len = headlen;
 400         if (headlen)
 401                 return;
 402
 403         pinfo = skb_shinfo(skb);
 404         frag0 = &pinfo->frags[0];
 405
 406         if (pinfo->nr_frags && skb_frag_page(frag0) &&
 407             !PageHighMem(skb_frag_page(frag0)) &&
 408             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 409                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 410                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 411                                                     skb_frag_size(frag0),
 412                                                     skb->end - skb->tail);
 413         }
 414 }
 415
 416 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 417 {
 418         struct skb_shared_info *pinfo = skb_shinfo(skb);
 419
 420         BUG_ON(skb->end - skb->tail < grow);
 421
 422         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 423
 424         skb->data_len -= grow;
 425         skb->tail += grow;
 426
 427         skb_frag_off_add(&pinfo->frags[0], grow);
 428         skb_frag_size_sub(&pinfo->frags[0], grow);
 429
 430         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 431                 skb_frag_unref(skb, 0);
 432                 memmove(pinfo->frags, pinfo->frags + 1,
 433                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 434         }
 435 }
 436
 437 static void gro_try_pull_from_frag0(struct sk_buff *skb)
 438 {
 439         int grow = skb_gro_offset(skb) - skb_headlen(skb);
 440
 441         if (grow > 0)
 442                 gro_pull_from_frag0(skb, grow);
 443 }
 444
 445 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 446 {
 447         struct sk_buff *oldest;
 448
 449         oldest = list_last_entry(head, struct sk_buff, list);
 450
 451         /* We are called with head length >= MAX_GRO_SKBS, so this is
 452          * impossible.
 453          */
 454         if (WARN_ON_ONCE(!oldest))
 455                 return;
 456
 457         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 458          * SKB to the chain.
 459          */
 460         skb_list_del_init(oldest);
 461         napi_gro_complete(napi, oldest);
 462 }
 463
 464 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 465 {
 466         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 467         struct gro_list *gro_list = &napi->gro_hash[bucket];
 468         struct list_head *head = &net_hotdata.offload_base;
 469         struct packet_offload *ptype;
 470         __be16 type = skb->protocol;
 471         struct sk_buff *pp = NULL;
 472         enum gro_result ret;
 473         int same_flow;
 474
 475         if (netif_elide_gro(skb->dev))
 476                 goto normal;
 477
 478         gro_list_prepare(&gro_list->list, skb);
 479
 480         rcu_read_lock();
 481         list_for_each_entry_rcu(ptype, head, list) {
 482                 if (ptype->type == type && ptype->callbacks.gro_receive)
 483                         goto found_ptype;
 484         }
 485         rcu_read_unlock();
 486         goto normal;
 487
 488 found_ptype:
 489         skb_set_network_header(skb, skb_gro_offset(skb));
 490         skb_reset_mac_len(skb);
 491         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 492         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 493                                         sizeof(u32))); /* Avoid slow unaligned acc */
 494         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 495         NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 496         NAPI_GRO_CB(skb)->count = 1;
 497         if (unlikely(skb_is_gso(skb))) {
 498                 NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 499                 /* Only support TCP and non DODGY users. */
 500                 if (!skb_is_gso_tcp(skb) ||
 501                     (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 502                         NAPI_GRO_CB(skb)->flush = 1;
 503         }
 504
 505         /* Setup for GRO checksum validation */
 506         switch (skb->ip_summed) {
 507         case CHECKSUM_COMPLETE:
 508                 NAPI_GRO_CB(skb)->csum = skb->csum;
 509                 NAPI_GRO_CB(skb)->csum_valid = 1;
 510                 break;
 511         case CHECKSUM_UNNECESSARY:
 512                 NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 513                 break;
 514         }
 515
 516         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 517                                 ipv6_gro_receive, inet_gro_receive,
 518                                 &gro_list->list, skb);
 519
 520         rcu_read_unlock();
 521
 522         if (PTR_ERR(pp) == -EINPROGRESS) {
 523                 ret = GRO_CONSUMED;
 524                 goto ok;
 525         }
 526
 527         same_flow = NAPI_GRO_CB(skb)->same_flow;
 528         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 529
 530         if (pp) {
 531                 skb_list_del_init(pp);
 532                 napi_gro_complete(napi, pp);
 533                 gro_list->count--;
 534         }
 535
 536         if (same_flow)
 537                 goto ok;
 538
 539         if (NAPI_GRO_CB(skb)->flush)
 540                 goto normal;
 541
 542         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 543                 gro_flush_oldest(napi, &gro_list->list);
 544         else
 545                 gro_list->count++;
 546
 547         /* Must be called before setting NAPI_GRO_CB(skb)->{age|last} */
 548         gro_try_pull_from_frag0(skb);
 549         NAPI_GRO_CB(skb)->age = jiffies;
 550         NAPI_GRO_CB(skb)->last = skb;
 551         if (!skb_is_gso(skb))
 552                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 553         list_add(&skb->list, &gro_list->list);
 554         ret = GRO_HELD;
 555 ok:
 556         if (gro_list->count) {
 557                 if (!test_bit(bucket, &napi->gro_bitmask))
 558                         __set_bit(bucket, &napi->gro_bitmask);
 559         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 560                 __clear_bit(bucket, &napi->gro_bitmask);
 561         }
 562
 563         return ret;
 564
 565 normal:
 566         ret = GRO_NORMAL;
 567         gro_try_pull_from_frag0(skb);
 568         goto ok;
 569 }
 570
 571 struct packet_offload *gro_find_receive_by_type(__be16 type)
 572 {
 573         struct list_head *offload_head = &net_hotdata.offload_base;
 574         struct packet_offload *ptype;
 575
 576         list_for_each_entry_rcu(ptype, offload_head, list) {
 577                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 578                         continue;
 579                 return ptype;
 580         }
 581         return NULL;
 582 }
 583 EXPORT_SYMBOL(gro_find_receive_by_type);
 584
 585 struct packet_offload *gro_find_complete_by_type(__be16 type)
 586 {
 587         struct list_head *offload_head = &net_hotdata.offload_base;
 588         struct packet_offload *ptype;
 589
 590         list_for_each_entry_rcu(ptype, offload_head, list) {
 591                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 592                         continue;
 593                 return ptype;
 594         }
 595         return NULL;
 596 }
 597 EXPORT_SYMBOL(gro_find_complete_by_type);
 598
 599 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 600                                     struct sk_buff *skb,
 601                                     gro_result_t ret)
 602 {
 603         switch (ret) {
 604         case GRO_NORMAL:
 605                 gro_normal_one(napi, skb, 1);
 606                 break;
 607
 608         case GRO_MERGED_FREE:
 609                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 610                         napi_skb_free_stolen_head(skb);
 611                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 612                         __kfree_skb(skb);
 613                 else
 614                         __napi_kfree_skb(skb, SKB_CONSUMED);
 615                 break;
 616
 617         case GRO_HELD:
 618         case GRO_MERGED:
 619         case GRO_CONSUMED:
 620                 break;
 621         }
 622
 623         return ret;
 624 }
 625
 626 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 627 {
 628         gro_result_t ret;
 629
 630         skb_mark_napi_id(skb, napi);
 631         trace_napi_gro_receive_entry(skb);
 632
 633         skb_gro_reset_offset(skb, 0);
 634
 635         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 636         trace_napi_gro_receive_exit(ret);
 637
 638         return ret;
 639 }
 640 EXPORT_SYMBOL(napi_gro_receive);
 641
 642 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 643 {
 644         if (unlikely(skb->pfmemalloc)) {
 645                 consume_skb(skb);
 646                 return;
 647         }
 648         __skb_pull(skb, skb_headlen(skb));
 649         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 650         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 651         __vlan_hwaccel_clear_tag(skb);
 652         skb->dev = napi->dev;
 653         skb->skb_iif = 0;
 654
 655         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 656         skb->pkt_type = PACKET_HOST;
 657
 658         skb->encapsulation = 0;
 659         skb_shinfo(skb)->gso_type = 0;
 660         skb_shinfo(skb)->gso_size = 0;
 661         if (unlikely(skb->slow_gro)) {
 662                 skb_orphan(skb);
 663                 skb_ext_reset(skb);
 664                 nf_reset_ct(skb);
 665                 skb->slow_gro = 0;
 666         }
 667
 668         napi->skb = skb;
 669 }
 670
 671 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 672 {
 673         struct sk_buff *skb = napi->skb;
 674
 675         if (!skb) {
 676                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 677                 if (skb) {
 678                         napi->skb = skb;
 679                         skb_mark_napi_id(skb, napi);
 680                 }
 681         }
 682         return skb;
 683 }
 684 EXPORT_SYMBOL(napi_get_frags);
 685
 686 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 687                                       struct sk_buff *skb,
 688                                       gro_result_t ret)
 689 {
 690         switch (ret) {
 691         case GRO_NORMAL:
 692         case GRO_HELD:
 693                 __skb_push(skb, ETH_HLEN);
 694                 skb->protocol = eth_type_trans(skb, skb->dev);
 695                 if (ret == GRO_NORMAL)
 696                         gro_normal_one(napi, skb, 1);
 697                 break;
 698
 699         case GRO_MERGED_FREE:
 700                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 701                         napi_skb_free_stolen_head(skb);
 702                 else
 703                         napi_reuse_skb(napi, skb);
 704                 break;
 705
 706         case GRO_MERGED:
 707         case GRO_CONSUMED:
 708                 break;
 709         }
 710
 711         return ret;
 712 }
 713
 714 /* Upper GRO stack assumes network header starts at gro_offset=0
 715  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 716  * We copy ethernet header into skb->data to have a common layout.
 717  */
 718 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 719 {
 720         struct sk_buff *skb = napi->skb;
 721         const struct ethhdr *eth;
 722         unsigned int hlen = sizeof(*eth);
 723
 724         napi->skb = NULL;
 725
 726         skb_reset_mac_header(skb);
 727         skb_gro_reset_offset(skb, hlen);
 728
 729         if (unlikely(!skb_gro_may_pull(skb, hlen))) {
 730                 eth = skb_gro_header_slow(skb, hlen, 0);
 731                 if (unlikely(!eth)) {
 732                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 733                                              __func__, napi->dev->name);
 734                         napi_reuse_skb(napi, skb);
 735                         return NULL;
 736                 }
 737         } else {
 738                 eth = (const struct ethhdr *)skb->data;
 739
 740                 if (NAPI_GRO_CB(skb)->frag0 != skb->data)
 741                         gro_pull_from_frag0(skb, hlen);
 742
 743                 NAPI_GRO_CB(skb)->frag0 += hlen;
 744                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 745         }
 746         __skb_pull(skb, hlen);
 747
 748         /*
 749          * This works because the only protocols we care about don't require
 750          * special handling.
 751          * We'll fix it up properly in napi_frags_finish()
 752          */
 753         skb->protocol = eth->h_proto;
 754
 755         return skb;
 756 }
 757
 758 gro_result_t napi_gro_frags(struct napi_struct *napi)
 759 {
 760         gro_result_t ret;
 761         struct sk_buff *skb = napi_frags_skb(napi);
 762
 763         trace_napi_gro_frags_entry(skb);
 764
 765         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 766         trace_napi_gro_frags_exit(ret);
 767
 768         return ret;
 769 }
 770 EXPORT_SYMBOL(napi_gro_frags);
 771
 772 /* Compute the checksum from gro_offset and return the folded value
 773  * after adding in any pseudo checksum.
 774  */
 775 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 776 {
 777         __wsum wsum;
 778         __sum16 sum;
 779
 780         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 781
 782         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 783         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 784         /* See comments in __skb_checksum_complete(). */
 785         if (likely(!sum)) {
 786                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 787                     !skb->csum_complete_sw)
 788                         netdev_rx_csum_fault(skb->dev, skb);
 789         }
 790
 791         NAPI_GRO_CB(skb)->csum = wsum;
 792         NAPI_GRO_CB(skb)->csum_valid = 1;
 793
 794         return sum;
 795 }
 796 EXPORT_SYMBOL(__skb_gro_checksum_complete);