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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 #include <net/gro.h>
0003 #include <net/dst_metadata.h>
0004 #include <net/busy_poll.h>
0005 #include <trace/events/net.h>
0006 
0007 #define MAX_GRO_SKBS 8
0008 
0009 /* This should be increased if a protocol with a bigger head is added. */
0010 #define GRO_MAX_HEAD (MAX_HEADER + 128)
0011 
0012 static DEFINE_SPINLOCK(offload_lock);
0013 static struct list_head offload_base __read_mostly = LIST_HEAD_INIT(offload_base);
0014 /* Maximum number of GRO_NORMAL skbs to batch up for list-RX */
0015 int gro_normal_batch __read_mostly = 8;
0016 
0017 /**
0018  *  dev_add_offload - register offload handlers
0019  *  @po: protocol offload declaration
0020  *
0021  *  Add protocol offload handlers to the networking stack. The passed
0022  *  &proto_offload is linked into kernel lists and may not be freed until
0023  *  it has been removed from the kernel lists.
0024  *
0025  *  This call does not sleep therefore it can not
0026  *  guarantee all CPU's that are in middle of receiving packets
0027  *  will see the new offload handlers (until the next received packet).
0028  */
0029 void dev_add_offload(struct packet_offload *po)
0030 {
0031     struct packet_offload *elem;
0032 
0033     spin_lock(&offload_lock);
0034     list_for_each_entry(elem, &offload_base, list) {
0035         if (po->priority < elem->priority)
0036             break;
0037     }
0038     list_add_rcu(&po->list, elem->list.prev);
0039     spin_unlock(&offload_lock);
0040 }
0041 EXPORT_SYMBOL(dev_add_offload);
0042 
0043 /**
0044  *  __dev_remove_offload     - remove offload handler
0045  *  @po: packet offload declaration
0046  *
0047  *  Remove a protocol offload handler that was previously added to the
0048  *  kernel offload handlers by dev_add_offload(). The passed &offload_type
0049  *  is removed from the kernel lists and can be freed or reused once this
0050  *  function returns.
0051  *
0052  *      The packet type might still be in use by receivers
0053  *  and must not be freed until after all the CPU's have gone
0054  *  through a quiescent state.
0055  */
0056 static void __dev_remove_offload(struct packet_offload *po)
0057 {
0058     struct list_head *head = &offload_base;
0059     struct packet_offload *po1;
0060 
0061     spin_lock(&offload_lock);
0062 
0063     list_for_each_entry(po1, head, list) {
0064         if (po == po1) {
0065             list_del_rcu(&po->list);
0066             goto out;
0067         }
0068     }
0069 
0070     pr_warn("dev_remove_offload: %p not found\n", po);
0071 out:
0072     spin_unlock(&offload_lock);
0073 }
0074 
0075 /**
0076  *  dev_remove_offload   - remove packet offload handler
0077  *  @po: packet offload declaration
0078  *
0079  *  Remove a packet offload handler that was previously added to the kernel
0080  *  offload handlers by dev_add_offload(). The passed &offload_type is
0081  *  removed from the kernel lists and can be freed or reused once this
0082  *  function returns.
0083  *
0084  *  This call sleeps to guarantee that no CPU is looking at the packet
0085  *  type after return.
0086  */
0087 void dev_remove_offload(struct packet_offload *po)
0088 {
0089     __dev_remove_offload(po);
0090 
0091     synchronize_net();
0092 }
0093 EXPORT_SYMBOL(dev_remove_offload);
0094 
0095 /**
0096  *  skb_eth_gso_segment - segmentation handler for ethernet protocols.
0097  *  @skb: buffer to segment
0098  *  @features: features for the output path (see dev->features)
0099  *  @type: Ethernet Protocol ID
0100  */
0101 struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
0102                     netdev_features_t features, __be16 type)
0103 {
0104     struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
0105     struct packet_offload *ptype;
0106 
0107     rcu_read_lock();
0108     list_for_each_entry_rcu(ptype, &offload_base, list) {
0109         if (ptype->type == type && ptype->callbacks.gso_segment) {
0110             segs = ptype->callbacks.gso_segment(skb, features);
0111             break;
0112         }
0113     }
0114     rcu_read_unlock();
0115 
0116     return segs;
0117 }
0118 EXPORT_SYMBOL(skb_eth_gso_segment);
0119 
0120 /**
0121  *  skb_mac_gso_segment - mac layer segmentation handler.
0122  *  @skb: buffer to segment
0123  *  @features: features for the output path (see dev->features)
0124  */
0125 struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
0126                     netdev_features_t features)
0127 {
0128     struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
0129     struct packet_offload *ptype;
0130     int vlan_depth = skb->mac_len;
0131     __be16 type = skb_network_protocol(skb, &vlan_depth);
0132 
0133     if (unlikely(!type))
0134         return ERR_PTR(-EINVAL);
0135 
0136     __skb_pull(skb, vlan_depth);
0137 
0138     rcu_read_lock();
0139     list_for_each_entry_rcu(ptype, &offload_base, list) {
0140         if (ptype->type == type && ptype->callbacks.gso_segment) {
0141             segs = ptype->callbacks.gso_segment(skb, features);
0142             break;
0143         }
0144     }
0145     rcu_read_unlock();
0146 
0147     __skb_push(skb, skb->data - skb_mac_header(skb));
0148 
0149     return segs;
0150 }
0151 EXPORT_SYMBOL(skb_mac_gso_segment);
0152 
0153 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
0154 {
0155     struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
0156     unsigned int offset = skb_gro_offset(skb);
0157     unsigned int headlen = skb_headlen(skb);
0158     unsigned int len = skb_gro_len(skb);
0159     unsigned int delta_truesize;
0160     unsigned int gro_max_size;
0161     unsigned int new_truesize;
0162     struct sk_buff *lp;
0163 
0164     /* pairs with WRITE_ONCE() in netif_set_gro_max_size() */
0165     gro_max_size = READ_ONCE(p->dev->gro_max_size);
0166 
0167     if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
0168         return -E2BIG;
0169 
0170     if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
0171         if (p->protocol != htons(ETH_P_IPV6) ||
0172             skb_headroom(p) < sizeof(struct hop_jumbo_hdr) ||
0173             ipv6_hdr(p)->nexthdr != IPPROTO_TCP ||
0174             p->encapsulation)
0175             return -E2BIG;
0176     }
0177 
0178     lp = NAPI_GRO_CB(p)->last;
0179     pinfo = skb_shinfo(lp);
0180 
0181     if (headlen <= offset) {
0182         skb_frag_t *frag;
0183         skb_frag_t *frag2;
0184         int i = skbinfo->nr_frags;
0185         int nr_frags = pinfo->nr_frags + i;
0186 
0187         if (nr_frags > MAX_SKB_FRAGS)
0188             goto merge;
0189 
0190         offset -= headlen;
0191         pinfo->nr_frags = nr_frags;
0192         skbinfo->nr_frags = 0;
0193 
0194         frag = pinfo->frags + nr_frags;
0195         frag2 = skbinfo->frags + i;
0196         do {
0197             *--frag = *--frag2;
0198         } while (--i);
0199 
0200         skb_frag_off_add(frag, offset);
0201         skb_frag_size_sub(frag, offset);
0202 
0203         /* all fragments truesize : remove (head size + sk_buff) */
0204         new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
0205         delta_truesize = skb->truesize - new_truesize;
0206 
0207         skb->truesize = new_truesize;
0208         skb->len -= skb->data_len;
0209         skb->data_len = 0;
0210 
0211         NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
0212         goto done;
0213     } else if (skb->head_frag) {
0214         int nr_frags = pinfo->nr_frags;
0215         skb_frag_t *frag = pinfo->frags + nr_frags;
0216         struct page *page = virt_to_head_page(skb->head);
0217         unsigned int first_size = headlen - offset;
0218         unsigned int first_offset;
0219 
0220         if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
0221             goto merge;
0222 
0223         first_offset = skb->data -
0224                    (unsigned char *)page_address(page) +
0225                    offset;
0226 
0227         pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
0228 
0229         __skb_frag_set_page(frag, page);
0230         skb_frag_off_set(frag, first_offset);
0231         skb_frag_size_set(frag, first_size);
0232 
0233         memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
0234         /* We dont need to clear skbinfo->nr_frags here */
0235 
0236         new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
0237         delta_truesize = skb->truesize - new_truesize;
0238         skb->truesize = new_truesize;
0239         NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
0240         goto done;
0241     }
0242 
0243 merge:
0244     /* sk owenrship - if any - completely transferred to the aggregated packet */
0245     skb->destructor = NULL;
0246     delta_truesize = skb->truesize;
0247     if (offset > headlen) {
0248         unsigned int eat = offset - headlen;
0249 
0250         skb_frag_off_add(&skbinfo->frags[0], eat);
0251         skb_frag_size_sub(&skbinfo->frags[0], eat);
0252         skb->data_len -= eat;
0253         skb->len -= eat;
0254         offset = headlen;
0255     }
0256 
0257     __skb_pull(skb, offset);
0258 
0259     if (NAPI_GRO_CB(p)->last == p)
0260         skb_shinfo(p)->frag_list = skb;
0261     else
0262         NAPI_GRO_CB(p)->last->next = skb;
0263     NAPI_GRO_CB(p)->last = skb;
0264     __skb_header_release(skb);
0265     lp = p;
0266 
0267 done:
0268     NAPI_GRO_CB(p)->count++;
0269     p->data_len += len;
0270     p->truesize += delta_truesize;
0271     p->len += len;
0272     if (lp != p) {
0273         lp->data_len += len;
0274         lp->truesize += delta_truesize;
0275         lp->len += len;
0276     }
0277     NAPI_GRO_CB(skb)->same_flow = 1;
0278     return 0;
0279 }
0280 
0281 
0282 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
0283 {
0284     struct packet_offload *ptype;
0285     __be16 type = skb->protocol;
0286     struct list_head *head = &offload_base;
0287     int err = -ENOENT;
0288 
0289     BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
0290 
0291     if (NAPI_GRO_CB(skb)->count == 1) {
0292         skb_shinfo(skb)->gso_size = 0;
0293         goto out;
0294     }
0295 
0296     rcu_read_lock();
0297     list_for_each_entry_rcu(ptype, head, list) {
0298         if (ptype->type != type || !ptype->callbacks.gro_complete)
0299             continue;
0300 
0301         err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
0302                      ipv6_gro_complete, inet_gro_complete,
0303                      skb, 0);
0304         break;
0305     }
0306     rcu_read_unlock();
0307 
0308     if (err) {
0309         WARN_ON(&ptype->list == head);
0310         kfree_skb(skb);
0311         return;
0312     }
0313 
0314 out:
0315     gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
0316 }
0317 
0318 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
0319                    bool flush_old)
0320 {
0321     struct list_head *head = &napi->gro_hash[index].list;
0322     struct sk_buff *skb, *p;
0323 
0324     list_for_each_entry_safe_reverse(skb, p, head, list) {
0325         if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
0326             return;
0327         skb_list_del_init(skb);
0328         napi_gro_complete(napi, skb);
0329         napi->gro_hash[index].count--;
0330     }
0331 
0332     if (!napi->gro_hash[index].count)
0333         __clear_bit(index, &napi->gro_bitmask);
0334 }
0335 
0336 /* napi->gro_hash[].list contains packets ordered by age.
0337  * youngest packets at the head of it.
0338  * Complete skbs in reverse order to reduce latencies.
0339  */
0340 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
0341 {
0342     unsigned long bitmask = napi->gro_bitmask;
0343     unsigned int i, base = ~0U;
0344 
0345     while ((i = ffs(bitmask)) != 0) {
0346         bitmask >>= i;
0347         base += i;
0348         __napi_gro_flush_chain(napi, base, flush_old);
0349     }
0350 }
0351 EXPORT_SYMBOL(napi_gro_flush);
0352 
0353 static void gro_list_prepare(const struct list_head *head,
0354                  const struct sk_buff *skb)
0355 {
0356     unsigned int maclen = skb->dev->hard_header_len;
0357     u32 hash = skb_get_hash_raw(skb);
0358     struct sk_buff *p;
0359 
0360     list_for_each_entry(p, head, list) {
0361         unsigned long diffs;
0362 
0363         NAPI_GRO_CB(p)->flush = 0;
0364 
0365         if (hash != skb_get_hash_raw(p)) {
0366             NAPI_GRO_CB(p)->same_flow = 0;
0367             continue;
0368         }
0369 
0370         diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
0371         diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
0372         if (skb_vlan_tag_present(p))
0373             diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
0374         diffs |= skb_metadata_differs(p, skb);
0375         if (maclen == ETH_HLEN)
0376             diffs |= compare_ether_header(skb_mac_header(p),
0377                               skb_mac_header(skb));
0378         else if (!diffs)
0379             diffs = memcmp(skb_mac_header(p),
0380                        skb_mac_header(skb),
0381                        maclen);
0382 
0383         /* in most common scenarions 'slow_gro' is 0
0384          * otherwise we are already on some slower paths
0385          * either skip all the infrequent tests altogether or
0386          * avoid trying too hard to skip each of them individually
0387          */
0388         if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
0389 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
0390             struct tc_skb_ext *skb_ext;
0391             struct tc_skb_ext *p_ext;
0392 #endif
0393 
0394             diffs |= p->sk != skb->sk;
0395             diffs |= skb_metadata_dst_cmp(p, skb);
0396             diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
0397 
0398 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
0399             skb_ext = skb_ext_find(skb, TC_SKB_EXT);
0400             p_ext = skb_ext_find(p, TC_SKB_EXT);
0401 
0402             diffs |= (!!p_ext) ^ (!!skb_ext);
0403             if (!diffs && unlikely(skb_ext))
0404                 diffs |= p_ext->chain ^ skb_ext->chain;
0405 #endif
0406         }
0407 
0408         NAPI_GRO_CB(p)->same_flow = !diffs;
0409     }
0410 }
0411 
0412 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
0413 {
0414     const struct skb_shared_info *pinfo = skb_shinfo(skb);
0415     const skb_frag_t *frag0 = &pinfo->frags[0];
0416 
0417     NAPI_GRO_CB(skb)->data_offset = 0;
0418     NAPI_GRO_CB(skb)->frag0 = NULL;
0419     NAPI_GRO_CB(skb)->frag0_len = 0;
0420 
0421     if (!skb_headlen(skb) && pinfo->nr_frags &&
0422         !PageHighMem(skb_frag_page(frag0)) &&
0423         (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
0424         NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
0425         NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
0426                             skb_frag_size(frag0),
0427                             skb->end - skb->tail);
0428     }
0429 }
0430 
0431 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
0432 {
0433     struct skb_shared_info *pinfo = skb_shinfo(skb);
0434 
0435     BUG_ON(skb->end - skb->tail < grow);
0436 
0437     memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
0438 
0439     skb->data_len -= grow;
0440     skb->tail += grow;
0441 
0442     skb_frag_off_add(&pinfo->frags[0], grow);
0443     skb_frag_size_sub(&pinfo->frags[0], grow);
0444 
0445     if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
0446         skb_frag_unref(skb, 0);
0447         memmove(pinfo->frags, pinfo->frags + 1,
0448             --pinfo->nr_frags * sizeof(pinfo->frags[0]));
0449     }
0450 }
0451 
0452 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
0453 {
0454     struct sk_buff *oldest;
0455 
0456     oldest = list_last_entry(head, struct sk_buff, list);
0457 
0458     /* We are called with head length >= MAX_GRO_SKBS, so this is
0459      * impossible.
0460      */
0461     if (WARN_ON_ONCE(!oldest))
0462         return;
0463 
0464     /* Do not adjust napi->gro_hash[].count, caller is adding a new
0465      * SKB to the chain.
0466      */
0467     skb_list_del_init(oldest);
0468     napi_gro_complete(napi, oldest);
0469 }
0470 
0471 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
0472 {
0473     u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
0474     struct gro_list *gro_list = &napi->gro_hash[bucket];
0475     struct list_head *head = &offload_base;
0476     struct packet_offload *ptype;
0477     __be16 type = skb->protocol;
0478     struct sk_buff *pp = NULL;
0479     enum gro_result ret;
0480     int same_flow;
0481     int grow;
0482 
0483     if (netif_elide_gro(skb->dev))
0484         goto normal;
0485 
0486     gro_list_prepare(&gro_list->list, skb);
0487 
0488     rcu_read_lock();
0489     list_for_each_entry_rcu(ptype, head, list) {
0490         if (ptype->type != type || !ptype->callbacks.gro_receive)
0491             continue;
0492 
0493         skb_set_network_header(skb, skb_gro_offset(skb));
0494         skb_reset_mac_len(skb);
0495         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
0496         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
0497                      sizeof(u32))); /* Avoid slow unaligned acc */
0498         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
0499         NAPI_GRO_CB(skb)->flush = skb_is_gso(skb) || skb_has_frag_list(skb);
0500         NAPI_GRO_CB(skb)->is_atomic = 1;
0501 
0502         /* Setup for GRO checksum validation */
0503         switch (skb->ip_summed) {
0504         case CHECKSUM_COMPLETE:
0505             NAPI_GRO_CB(skb)->csum = skb->csum;
0506             NAPI_GRO_CB(skb)->csum_valid = 1;
0507             break;
0508         case CHECKSUM_UNNECESSARY:
0509             NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
0510             break;
0511         }
0512 
0513         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
0514                     ipv6_gro_receive, inet_gro_receive,
0515                     &gro_list->list, skb);
0516         break;
0517     }
0518     rcu_read_unlock();
0519 
0520     if (&ptype->list == head)
0521         goto normal;
0522 
0523     if (PTR_ERR(pp) == -EINPROGRESS) {
0524         ret = GRO_CONSUMED;
0525         goto ok;
0526     }
0527 
0528     same_flow = NAPI_GRO_CB(skb)->same_flow;
0529     ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
0530 
0531     if (pp) {
0532         skb_list_del_init(pp);
0533         napi_gro_complete(napi, pp);
0534         gro_list->count--;
0535     }
0536 
0537     if (same_flow)
0538         goto ok;
0539 
0540     if (NAPI_GRO_CB(skb)->flush)
0541         goto normal;
0542 
0543     if (unlikely(gro_list->count >= MAX_GRO_SKBS))
0544         gro_flush_oldest(napi, &gro_list->list);
0545     else
0546         gro_list->count++;
0547 
0548     NAPI_GRO_CB(skb)->count = 1;
0549     NAPI_GRO_CB(skb)->age = jiffies;
0550     NAPI_GRO_CB(skb)->last = skb;
0551     skb_shinfo(skb)->gso_size = skb_gro_len(skb);
0552     list_add(&skb->list, &gro_list->list);
0553     ret = GRO_HELD;
0554 
0555 pull:
0556     grow = skb_gro_offset(skb) - skb_headlen(skb);
0557     if (grow > 0)
0558         gro_pull_from_frag0(skb, grow);
0559 ok:
0560     if (gro_list->count) {
0561         if (!test_bit(bucket, &napi->gro_bitmask))
0562             __set_bit(bucket, &napi->gro_bitmask);
0563     } else if (test_bit(bucket, &napi->gro_bitmask)) {
0564         __clear_bit(bucket, &napi->gro_bitmask);
0565     }
0566 
0567     return ret;
0568 
0569 normal:
0570     ret = GRO_NORMAL;
0571     goto pull;
0572 }
0573 
0574 struct packet_offload *gro_find_receive_by_type(__be16 type)
0575 {
0576     struct list_head *offload_head = &offload_base;
0577     struct packet_offload *ptype;
0578 
0579     list_for_each_entry_rcu(ptype, offload_head, list) {
0580         if (ptype->type != type || !ptype->callbacks.gro_receive)
0581             continue;
0582         return ptype;
0583     }
0584     return NULL;
0585 }
0586 EXPORT_SYMBOL(gro_find_receive_by_type);
0587 
0588 struct packet_offload *gro_find_complete_by_type(__be16 type)
0589 {
0590     struct list_head *offload_head = &offload_base;
0591     struct packet_offload *ptype;
0592 
0593     list_for_each_entry_rcu(ptype, offload_head, list) {
0594         if (ptype->type != type || !ptype->callbacks.gro_complete)
0595             continue;
0596         return ptype;
0597     }
0598     return NULL;
0599 }
0600 EXPORT_SYMBOL(gro_find_complete_by_type);
0601 
0602 static gro_result_t napi_skb_finish(struct napi_struct *napi,
0603                     struct sk_buff *skb,
0604                     gro_result_t ret)
0605 {
0606     switch (ret) {
0607     case GRO_NORMAL:
0608         gro_normal_one(napi, skb, 1);
0609         break;
0610 
0611     case GRO_MERGED_FREE:
0612         if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
0613             napi_skb_free_stolen_head(skb);
0614         else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
0615             __kfree_skb(skb);
0616         else
0617             __kfree_skb_defer(skb);
0618         break;
0619 
0620     case GRO_HELD:
0621     case GRO_MERGED:
0622     case GRO_CONSUMED:
0623         break;
0624     }
0625 
0626     return ret;
0627 }
0628 
0629 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
0630 {
0631     gro_result_t ret;
0632 
0633     skb_mark_napi_id(skb, napi);
0634     trace_napi_gro_receive_entry(skb);
0635 
0636     skb_gro_reset_offset(skb, 0);
0637 
0638     ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
0639     trace_napi_gro_receive_exit(ret);
0640 
0641     return ret;
0642 }
0643 EXPORT_SYMBOL(napi_gro_receive);
0644 
0645 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
0646 {
0647     if (unlikely(skb->pfmemalloc)) {
0648         consume_skb(skb);
0649         return;
0650     }
0651     __skb_pull(skb, skb_headlen(skb));
0652     /* restore the reserve we had after netdev_alloc_skb_ip_align() */
0653     skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
0654     __vlan_hwaccel_clear_tag(skb);
0655     skb->dev = napi->dev;
0656     skb->skb_iif = 0;
0657 
0658     /* eth_type_trans() assumes pkt_type is PACKET_HOST */
0659     skb->pkt_type = PACKET_HOST;
0660 
0661     skb->encapsulation = 0;
0662     skb_shinfo(skb)->gso_type = 0;
0663     if (unlikely(skb->slow_gro)) {
0664         skb_orphan(skb);
0665         skb_ext_reset(skb);
0666         nf_reset_ct(skb);
0667         skb->slow_gro = 0;
0668     }
0669 
0670     napi->skb = skb;
0671 }
0672 
0673 struct sk_buff *napi_get_frags(struct napi_struct *napi)
0674 {
0675     struct sk_buff *skb = napi->skb;
0676 
0677     if (!skb) {
0678         skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
0679         if (skb) {
0680             napi->skb = skb;
0681             skb_mark_napi_id(skb, napi);
0682         }
0683     }
0684     return skb;
0685 }
0686 EXPORT_SYMBOL(napi_get_frags);
0687 
0688 static gro_result_t napi_frags_finish(struct napi_struct *napi,
0689                       struct sk_buff *skb,
0690                       gro_result_t ret)
0691 {
0692     switch (ret) {
0693     case GRO_NORMAL:
0694     case GRO_HELD:
0695         __skb_push(skb, ETH_HLEN);
0696         skb->protocol = eth_type_trans(skb, skb->dev);
0697         if (ret == GRO_NORMAL)
0698             gro_normal_one(napi, skb, 1);
0699         break;
0700 
0701     case GRO_MERGED_FREE:
0702         if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
0703             napi_skb_free_stolen_head(skb);
0704         else
0705             napi_reuse_skb(napi, skb);
0706         break;
0707 
0708     case GRO_MERGED:
0709     case GRO_CONSUMED:
0710         break;
0711     }
0712 
0713     return ret;
0714 }
0715 
0716 /* Upper GRO stack assumes network header starts at gro_offset=0
0717  * Drivers could call both napi_gro_frags() and napi_gro_receive()
0718  * We copy ethernet header into skb->data to have a common layout.
0719  */
0720 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
0721 {
0722     struct sk_buff *skb = napi->skb;
0723     const struct ethhdr *eth;
0724     unsigned int hlen = sizeof(*eth);
0725 
0726     napi->skb = NULL;
0727 
0728     skb_reset_mac_header(skb);
0729     skb_gro_reset_offset(skb, hlen);
0730 
0731     if (unlikely(skb_gro_header_hard(skb, hlen))) {
0732         eth = skb_gro_header_slow(skb, hlen, 0);
0733         if (unlikely(!eth)) {
0734             net_warn_ratelimited("%s: dropping impossible skb from %s\n",
0735                          __func__, napi->dev->name);
0736             napi_reuse_skb(napi, skb);
0737             return NULL;
0738         }
0739     } else {
0740         eth = (const struct ethhdr *)skb->data;
0741         gro_pull_from_frag0(skb, hlen);
0742         NAPI_GRO_CB(skb)->frag0 += hlen;
0743         NAPI_GRO_CB(skb)->frag0_len -= hlen;
0744     }
0745     __skb_pull(skb, hlen);
0746 
0747     /*
0748      * This works because the only protocols we care about don't require
0749      * special handling.
0750      * We'll fix it up properly in napi_frags_finish()
0751      */
0752     skb->protocol = eth->h_proto;
0753 
0754     return skb;
0755 }
0756 
0757 gro_result_t napi_gro_frags(struct napi_struct *napi)
0758 {
0759     gro_result_t ret;
0760     struct sk_buff *skb = napi_frags_skb(napi);
0761 
0762     trace_napi_gro_frags_entry(skb);
0763 
0764     ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
0765     trace_napi_gro_frags_exit(ret);
0766 
0767     return ret;
0768 }
0769 EXPORT_SYMBOL(napi_gro_frags);
0770 
0771 /* Compute the checksum from gro_offset and return the folded value
0772  * after adding in any pseudo checksum.
0773  */
0774 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
0775 {
0776     __wsum wsum;
0777     __sum16 sum;
0778 
0779     wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
0780 
0781     /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
0782     sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
0783     /* See comments in __skb_checksum_complete(). */
0784     if (likely(!sum)) {
0785         if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
0786             !skb->csum_complete_sw)
0787             netdev_rx_csum_fault(skb->dev, skb);
0788     }
0789 
0790     NAPI_GRO_CB(skb)->csum = wsum;
0791     NAPI_GRO_CB(skb)->csum_valid = 1;
0792 
0793     return sum;
0794 }
0795 EXPORT_SYMBOL(__skb_gro_checksum_complete);
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