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 gro_max_size;
 102         unsigned int new_truesize;
 103         struct sk_buff *lp;
 104         int segs;
 105
 106         /* Do not splice page pool based packets w/ non-page pool
 107          * packets. This can result in reference count issues as page
 108          * pool pages will not decrement the reference count and will
 109          * instead be immediately returned to the pool or have frag
 110          * count decremented.
 111          */
 112         if (p->pp_recycle != skb->pp_recycle)
 113                 return -ETOOMANYREFS;
 114
 115         /* pairs with WRITE_ONCE() in netif_set_gro(_ipv4)_max_size() */
 116         gro_max_size = p->protocol == htons(ETH_P_IPV6) ?
 117                         READ_ONCE(p->dev->gro_max_size) :
 118                         READ_ONCE(p->dev->gro_ipv4_max_size);
 119
 120         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 121                 return -E2BIG;
 122
 123         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 124                 if (NAPI_GRO_CB(skb)->proto != IPPROTO_TCP ||
 125                     (p->protocol == htons(ETH_P_IPV6) &&
 126                      skb_headroom(p) < sizeof(struct hop_jumbo_hdr)) ||
 127                     p->encapsulation)
 128                         return -E2BIG;
 129         }
 130
 131         segs = NAPI_GRO_CB(skb)->count;
 132         lp = NAPI_GRO_CB(p)->last;
 133         pinfo = skb_shinfo(lp);
 134
 135         if (headlen <= offset) {
 136                 skb_frag_t *frag;
 137                 skb_frag_t *frag2;
 138                 int i = skbinfo->nr_frags;
 139                 int nr_frags = pinfo->nr_frags + i;
 140
 141                 if (nr_frags > MAX_SKB_FRAGS)
 142                         goto merge;
 143
 144                 offset -= headlen;
 145                 pinfo->nr_frags = nr_frags;
 146                 skbinfo->nr_frags = 0;
 147
 148                 frag = pinfo->frags + nr_frags;
 149                 frag2 = skbinfo->frags + i;
 150                 do {
 151                         *--frag = *--frag2;
 152                 } while (--i);
 153
 154                 skb_frag_off_add(frag, offset);
 155                 skb_frag_size_sub(frag, offset);
 156
 157                 /* all fragments truesize : remove (head size + sk_buff) */
 158                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 159                 delta_truesize = skb->truesize - new_truesize;
 160
 161                 skb->truesize = new_truesize;
 162                 skb->len -= skb->data_len;
 163                 skb->data_len = 0;
 164
 165                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 166                 goto done;
 167         } else if (skb->head_frag) {
 168                 int nr_frags = pinfo->nr_frags;
 169                 skb_frag_t *frag = pinfo->frags + nr_frags;
 170                 struct page *page = virt_to_head_page(skb->head);
 171                 unsigned int first_size = headlen - offset;
 172                 unsigned int first_offset;
 173
 174                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 175                         goto merge;
 176
 177                 first_offset = skb->data -
 178                                (unsigned char *)page_address(page) +
 179                                offset;
 180
 181                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 182
 183                 skb_frag_fill_page_desc(frag, page, first_offset, first_size);
 184
 185                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 186                 /* We dont need to clear skbinfo->nr_frags here */
 187
 188                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 189                 delta_truesize = skb->truesize - new_truesize;
 190                 skb->truesize = new_truesize;
 191                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 192                 goto done;
 193         }
 194
 195 merge:
 196         /* sk ownership - if any - completely transferred to the aggregated packet */
 197         skb->destructor = NULL;
 198         skb->sk = NULL;
 199         delta_truesize = skb->truesize;
 200         if (offset > headlen) {
 201                 unsigned int eat = offset - headlen;
 202
 203                 skb_frag_off_add(&skbinfo->frags[0], eat);
 204                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 205                 skb->data_len -= eat;
 206                 skb->len -= eat;
 207                 offset = headlen;
 208         }
 209
 210         __skb_pull(skb, offset);
 211
 212         if (NAPI_GRO_CB(p)->last == p)
 213                 skb_shinfo(p)->frag_list = skb;
 214         else
 215                 NAPI_GRO_CB(p)->last->next = skb;
 216         NAPI_GRO_CB(p)->last = skb;
 217         __skb_header_release(skb);
 218         lp = p;
 219
 220 done:
 221         NAPI_GRO_CB(p)->count += segs;
 222         p->data_len += len;
 223         p->truesize += delta_truesize;
 224         p->len += len;
 225         if (lp != p) {
 226                 lp->data_len += len;
 227                 lp->truesize += delta_truesize;
 228                 lp->len += len;
 229         }
 230         NAPI_GRO_CB(skb)->same_flow = 1;
 231         return 0;
 232 }
 233
 234 int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
 235 {
 236         if (unlikely(p->len + skb->len >= 65536))
 237                 return -E2BIG;
 238
 239         if (NAPI_GRO_CB(p)->last == p)
 240                 skb_shinfo(p)->frag_list = skb;
 241         else
 242                 NAPI_GRO_CB(p)->last->next = skb;
 243
 244         skb_pull(skb, skb_gro_offset(skb));
 245
 246         NAPI_GRO_CB(p)->last = skb;
 247         NAPI_GRO_CB(p)->count++;
 248         p->data_len += skb->len;
 249
 250         /* sk ownership - if any - completely transferred to the aggregated packet */
 251         skb->destructor = NULL;
 252         skb->sk = NULL;
 253         p->truesize += skb->truesize;
 254         p->len += skb->len;
 255
 256         NAPI_GRO_CB(skb)->same_flow = 1;
 257
 258         return 0;
 259 }
 260
 261
 262 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 263 {
 264         struct list_head *head = &net_hotdata.offload_base;
 265         struct packet_offload *ptype;
 266         __be16 type = skb->protocol;
 267         int err = -ENOENT;
 268
 269         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 270
 271         if (NAPI_GRO_CB(skb)->count == 1) {
 272                 skb_shinfo(skb)->gso_size = 0;
 273                 goto out;
 274         }
 275
 276         rcu_read_lock();
 277         list_for_each_entry_rcu(ptype, head, list) {
 278                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 279                         continue;
 280
 281                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 282                                          ipv6_gro_complete, inet_gro_complete,
 283                                          skb, 0);
 284                 break;
 285         }
 286         rcu_read_unlock();
 287
 288         if (err) {
 289                 WARN_ON(&ptype->list == head);
 290                 kfree_skb(skb);
 291                 return;
 292         }
 293
 294 out:
 295         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 296 }
 297
 298 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 299                                    bool flush_old)
 300 {
 301         struct list_head *head = &napi->gro_hash[index].list;
 302         struct sk_buff *skb, *p;
 303
 304         list_for_each_entry_safe_reverse(skb, p, head, list) {
 305                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 306                         return;
 307                 skb_list_del_init(skb);
 308                 napi_gro_complete(napi, skb);
 309                 napi->gro_hash[index].count--;
 310         }
 311
 312         if (!napi->gro_hash[index].count)
 313                 __clear_bit(index, &napi->gro_bitmask);
 314 }
 315
 316 /* napi->gro_hash[].list contains packets ordered by age.
 317  * youngest packets at the head of it.
 318  * Complete skbs in reverse order to reduce latencies.
 319  */
 320 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 321 {
 322         unsigned long bitmask = napi->gro_bitmask;
 323         unsigned int i, base = ~0U;
 324
 325         while ((i = ffs(bitmask)) != 0) {
 326                 bitmask >>= i;
 327                 base += i;
 328                 __napi_gro_flush_chain(napi, base, flush_old);
 329         }
 330 }
 331 EXPORT_SYMBOL(napi_gro_flush);
 332
 333 static unsigned long gro_list_prepare_tc_ext(const struct sk_buff *skb,
 334                                              const struct sk_buff *p,
 335                                              unsigned long diffs)
 336 {
 337 #if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 338         struct tc_skb_ext *skb_ext;
 339         struct tc_skb_ext *p_ext;
 340
 341         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 342         p_ext = skb_ext_find(p, TC_SKB_EXT);
 343
 344         diffs |= (!!p_ext) ^ (!!skb_ext);
 345         if (!diffs && unlikely(skb_ext))
 346                 diffs |= p_ext->chain ^ skb_ext->chain;
 347 #endif
 348         return diffs;
 349 }
 350
 351 static void gro_list_prepare(const struct list_head *head,
 352                              const struct sk_buff *skb)
 353 {
 354         unsigned int maclen = skb->dev->hard_header_len;
 355         u32 hash = skb_get_hash_raw(skb);
 356         struct sk_buff *p;
 357
 358         list_for_each_entry(p, head, list) {
 359                 unsigned long diffs;
 360
 361                 if (hash != skb_get_hash_raw(p)) {
 362                         NAPI_GRO_CB(p)->same_flow = 0;
 363                         continue;
 364                 }
 365
 366                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 367                 diffs |= p->vlan_all ^ skb->vlan_all;
 368                 diffs |= skb_metadata_differs(p, skb);
 369                 if (maclen == ETH_HLEN)
 370                         diffs |= compare_ether_header(skb_mac_header(p),
 371                                                       skb_mac_header(skb));
 372                 else if (!diffs)
 373                         diffs = memcmp(skb_mac_header(p),
 374                                        skb_mac_header(skb),
 375                                        maclen);
 376
 377                 /* in most common scenarions 'slow_gro' is 0
 378                  * otherwise we are already on some slower paths
 379                  * either skip all the infrequent tests altogether or
 380                  * avoid trying too hard to skip each of them individually
 381                  */
 382                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 383                         diffs |= p->sk != skb->sk;
 384                         diffs |= skb_metadata_dst_cmp(p, skb);
 385                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 386
 387                         diffs |= gro_list_prepare_tc_ext(skb, p, diffs);
 388                 }
 389
 390                 NAPI_GRO_CB(p)->same_flow = !diffs;
 391         }
 392 }
 393
 394 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 395 {
 396         const struct skb_shared_info *pinfo;
 397         const skb_frag_t *frag0;
 398         unsigned int headlen;
 399
 400         NAPI_GRO_CB(skb)->network_offset = 0;
 401         NAPI_GRO_CB(skb)->data_offset = 0;
 402         headlen = skb_headlen(skb);
 403         NAPI_GRO_CB(skb)->frag0 = skb->data;
 404         NAPI_GRO_CB(skb)->frag0_len = headlen;
 405         if (headlen)
 406                 return;
 407
 408         pinfo = skb_shinfo(skb);
 409         frag0 = &pinfo->frags[0];
 410
 411         if (pinfo->nr_frags && !PageHighMem(skb_frag_page(frag0)) &&
 412             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 413                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 414                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 415                                                     skb_frag_size(frag0),
 416                                                     skb->end - skb->tail);
 417         }
 418 }
 419
 420 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 421 {
 422         struct skb_shared_info *pinfo = skb_shinfo(skb);
 423
 424         BUG_ON(skb->end - skb->tail < grow);
 425
 426         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 427
 428         skb->data_len -= grow;
 429         skb->tail += grow;
 430
 431         skb_frag_off_add(&pinfo->frags[0], grow);
 432         skb_frag_size_sub(&pinfo->frags[0], grow);
 433
 434         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 435                 skb_frag_unref(skb, 0);
 436                 memmove(pinfo->frags, pinfo->frags + 1,
 437                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 438         }
 439 }
 440
 441 static void gro_try_pull_from_frag0(struct sk_buff *skb)
 442 {
 443         int grow = skb_gro_offset(skb) - skb_headlen(skb);
 444
 445         if (grow > 0)
 446                 gro_pull_from_frag0(skb, grow);
 447 }
 448
 449 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 450 {
 451         struct sk_buff *oldest;
 452
 453         oldest = list_last_entry(head, struct sk_buff, list);
 454
 455         /* We are called with head length >= MAX_GRO_SKBS, so this is
 456          * impossible.
 457          */
 458         if (WARN_ON_ONCE(!oldest))
 459                 return;
 460
 461         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 462          * SKB to the chain.
 463          */
 464         skb_list_del_init(oldest);
 465         napi_gro_complete(napi, oldest);
 466 }
 467
 468 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 469 {
 470         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 471         struct gro_list *gro_list = &napi->gro_hash[bucket];
 472         struct list_head *head = &net_hotdata.offload_base;
 473         struct packet_offload *ptype;
 474         __be16 type = skb->protocol;
 475         struct sk_buff *pp = NULL;
 476         enum gro_result ret;
 477         int same_flow;
 478
 479         if (netif_elide_gro(skb->dev))
 480                 goto normal;
 481
 482         gro_list_prepare(&gro_list->list, skb);
 483
 484         rcu_read_lock();
 485         list_for_each_entry_rcu(ptype, head, list) {
 486                 if (ptype->type == type && ptype->callbacks.gro_receive)
 487                         goto found_ptype;
 488         }
 489         rcu_read_unlock();
 490         goto normal;
 491
 492 found_ptype:
 493         skb_set_network_header(skb, skb_gro_offset(skb));
 494         skb_reset_mac_len(skb);
 495         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 496         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 497                                         sizeof(u32))); /* Avoid slow unaligned acc */
 498         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 499         NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 500         NAPI_GRO_CB(skb)->count = 1;
 501         if (unlikely(skb_is_gso(skb))) {
 502                 NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 503                 /* Only support TCP and non DODGY users. */
 504                 if (!skb_is_gso_tcp(skb) ||
 505                     (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 506                         NAPI_GRO_CB(skb)->flush = 1;
 507         }
 508
 509         /* Setup for GRO checksum validation */
 510         switch (skb->ip_summed) {
 511         case CHECKSUM_COMPLETE:
 512                 NAPI_GRO_CB(skb)->csum = skb->csum;
 513                 NAPI_GRO_CB(skb)->csum_valid = 1;
 514                 break;
 515         case CHECKSUM_UNNECESSARY:
 516                 NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 517                 break;
 518         }
 519
 520         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 521                                 ipv6_gro_receive, inet_gro_receive,
 522                                 &gro_list->list, skb);
 523
 524         rcu_read_unlock();
 525
 526         if (PTR_ERR(pp) == -EINPROGRESS) {
 527                 ret = GRO_CONSUMED;
 528                 goto ok;
 529         }
 530
 531         same_flow = NAPI_GRO_CB(skb)->same_flow;
 532         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 533
 534         if (pp) {
 535                 skb_list_del_init(pp);
 536                 napi_gro_complete(napi, pp);
 537                 gro_list->count--;
 538         }
 539
 540         if (same_flow)
 541                 goto ok;
 542
 543         if (NAPI_GRO_CB(skb)->flush)
 544                 goto normal;
 545
 546         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 547                 gro_flush_oldest(napi, &gro_list->list);
 548         else
 549                 gro_list->count++;
 550
 551         /* Must be called before setting NAPI_GRO_CB(skb)->{age|last} */
 552         gro_try_pull_from_frag0(skb);
 553         NAPI_GRO_CB(skb)->age = jiffies;
 554         NAPI_GRO_CB(skb)->last = skb;
 555         if (!skb_is_gso(skb))
 556                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 557         list_add(&skb->list, &gro_list->list);
 558         ret = GRO_HELD;
 559 ok:
 560         if (gro_list->count) {
 561                 if (!test_bit(bucket, &napi->gro_bitmask))
 562                         __set_bit(bucket, &napi->gro_bitmask);
 563         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 564                 __clear_bit(bucket, &napi->gro_bitmask);
 565         }
 566
 567         return ret;
 568
 569 normal:
 570         ret = GRO_NORMAL;
 571         gro_try_pull_from_frag0(skb);
 572         goto ok;
 573 }
 574
 575 struct packet_offload *gro_find_receive_by_type(__be16 type)
 576 {
 577         struct list_head *offload_head = &net_hotdata.offload_base;
 578         struct packet_offload *ptype;
 579
 580         list_for_each_entry_rcu(ptype, offload_head, list) {
 581                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 582                         continue;
 583                 return ptype;
 584         }
 585         return NULL;
 586 }
 587 EXPORT_SYMBOL(gro_find_receive_by_type);
 588
 589 struct packet_offload *gro_find_complete_by_type(__be16 type)
 590 {
 591         struct list_head *offload_head = &net_hotdata.offload_base;
 592         struct packet_offload *ptype;
 593
 594         list_for_each_entry_rcu(ptype, offload_head, list) {
 595                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 596                         continue;
 597                 return ptype;
 598         }
 599         return NULL;
 600 }
 601 EXPORT_SYMBOL(gro_find_complete_by_type);
 602
 603 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 604                                     struct sk_buff *skb,
 605                                     gro_result_t ret)
 606 {
 607         switch (ret) {
 608         case GRO_NORMAL:
 609                 gro_normal_one(napi, skb, 1);
 610                 break;
 611
 612         case GRO_MERGED_FREE:
 613                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 614                         napi_skb_free_stolen_head(skb);
 615                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 616                         __kfree_skb(skb);
 617                 else
 618                         __napi_kfree_skb(skb, SKB_CONSUMED);
 619                 break;
 620
 621         case GRO_HELD:
 622         case GRO_MERGED:
 623         case GRO_CONSUMED:
 624                 break;
 625         }
 626
 627         return ret;
 628 }
 629
 630 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 631 {
 632         gro_result_t ret;
 633
 634         skb_mark_napi_id(skb, napi);
 635         trace_napi_gro_receive_entry(skb);
 636
 637         skb_gro_reset_offset(skb, 0);
 638
 639         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 640         trace_napi_gro_receive_exit(ret);
 641
 642         return ret;
 643 }
 644 EXPORT_SYMBOL(napi_gro_receive);
 645
 646 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 647 {
 648         if (unlikely(skb->pfmemalloc)) {
 649                 consume_skb(skb);
 650                 return;
 651         }
 652         __skb_pull(skb, skb_headlen(skb));
 653         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 654         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 655         __vlan_hwaccel_clear_tag(skb);
 656         skb->dev = napi->dev;
 657         skb->skb_iif = 0;
 658
 659         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 660         skb->pkt_type = PACKET_HOST;
 661
 662         skb->encapsulation = 0;
 663         skb_shinfo(skb)->gso_type = 0;
 664         skb_shinfo(skb)->gso_size = 0;
 665         if (unlikely(skb->slow_gro)) {
 666                 skb_orphan(skb);
 667                 skb_ext_reset(skb);
 668                 nf_reset_ct(skb);
 669                 skb->slow_gro = 0;
 670         }
 671
 672         napi->skb = skb;
 673 }
 674
 675 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 676 {
 677         struct sk_buff *skb = napi->skb;
 678
 679         if (!skb) {
 680                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 681                 if (skb) {
 682                         napi->skb = skb;
 683                         skb_mark_napi_id(skb, napi);
 684                 }
 685         }
 686         return skb;
 687 }
 688 EXPORT_SYMBOL(napi_get_frags);
 689
 690 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 691                                       struct sk_buff *skb,
 692                                       gro_result_t ret)
 693 {
 694         switch (ret) {
 695         case GRO_NORMAL:
 696         case GRO_HELD:
 697                 __skb_push(skb, ETH_HLEN);
 698                 skb->protocol = eth_type_trans(skb, skb->dev);
 699                 if (ret == GRO_NORMAL)
 700                         gro_normal_one(napi, skb, 1);
 701                 break;
 702
 703         case GRO_MERGED_FREE:
 704                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 705                         napi_skb_free_stolen_head(skb);
 706                 else
 707                         napi_reuse_skb(napi, skb);
 708                 break;
 709
 710         case GRO_MERGED:
 711         case GRO_CONSUMED:
 712                 break;
 713         }
 714
 715         return ret;
 716 }
 717
 718 /* Upper GRO stack assumes network header starts at gro_offset=0
 719  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 720  * We copy ethernet header into skb->data to have a common layout.
 721  */
 722 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 723 {
 724         struct sk_buff *skb = napi->skb;
 725         const struct ethhdr *eth;
 726         unsigned int hlen = sizeof(*eth);
 727
 728         napi->skb = NULL;
 729
 730         skb_reset_mac_header(skb);
 731         skb_gro_reset_offset(skb, hlen);
 732
 733         if (unlikely(!skb_gro_may_pull(skb, hlen))) {
 734                 eth = skb_gro_header_slow(skb, hlen, 0);
 735                 if (unlikely(!eth)) {
 736                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 737                                              __func__, napi->dev->name);
 738                         napi_reuse_skb(napi, skb);
 739                         return NULL;
 740                 }
 741         } else {
 742                 eth = (const struct ethhdr *)skb->data;
 743
 744                 if (NAPI_GRO_CB(skb)->frag0 != skb->data)
 745                         gro_pull_from_frag0(skb, hlen);
 746
 747                 NAPI_GRO_CB(skb)->frag0 += hlen;
 748                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 749         }
 750         __skb_pull(skb, hlen);
 751
 752         /*
 753          * This works because the only protocols we care about don't require
 754          * special handling.
 755          * We'll fix it up properly in napi_frags_finish()
 756          */
 757         skb->protocol = eth->h_proto;
 758
 759         return skb;
 760 }
 761
 762 gro_result_t napi_gro_frags(struct napi_struct *napi)
 763 {
 764         gro_result_t ret;
 765         struct sk_buff *skb = napi_frags_skb(napi);
 766
 767         trace_napi_gro_frags_entry(skb);
 768
 769         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 770         trace_napi_gro_frags_exit(ret);
 771
 772         return ret;
 773 }
 774 EXPORT_SYMBOL(napi_gro_frags);
 775
 776 /* Compute the checksum from gro_offset and return the folded value
 777  * after adding in any pseudo checksum.
 778  */
 779 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 780 {
 781         __wsum wsum;
 782         __sum16 sum;
 783
 784         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 785
 786         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 787         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 788         /* See comments in __skb_checksum_complete(). */
 789         if (likely(!sum)) {
 790                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 791                     !skb->csum_complete_sw)
 792                         netdev_rx_csum_fault(skb->dev, skb);
 793         }
 794
 795         NAPI_GRO_CB(skb)->csum = wsum;
 796         NAPI_GRO_CB(skb)->csum_valid = 1;
 797
 798         return sum;
 799 }
 800 EXPORT_SYMBOL(__skb_gro_checksum_complete);