drm/tests: hdmi: Fix memory leaks in drm_display_mode_from_cea_vic()

[drm/drm-misc.git] / net / core / gro.c

// SPDX-License-Identifier: GPL-2.0-or-later
#include <net/gro.h>
#include <net/dst_metadata.h>
#include <net/busy_poll.h>
#include <trace/events/net.h>
#include <linux/skbuff_ref.h>

#define MAX_GRO_SKBS 8

/* This should be increased if a protocol with a bigger head is added. */
#define GRO_MAX_HEAD (MAX_HEADER + 128)

static DEFINE_SPINLOCK(offload_lock);

/**
 *      dev_add_offload - register offload handlers
 *      @po: protocol offload declaration
 *
 *      Add protocol offload handlers to the networking stack. The passed
 *      &proto_offload is linked into kernel lists and may not be freed until
 *      it has been removed from the kernel lists.
 *
 *      This call does not sleep therefore it can not
 *      guarantee all CPU's that are in middle of receiving packets
 *      will see the new offload handlers (until the next received packet).
 */
void dev_add_offload(struct packet_offload *po)
{
        struct packet_offload *elem;

        spin_lock(&offload_lock);
        list_for_each_entry(elem, &net_hotdata.offload_base, list) {
                if (po->priority < elem->priority)
                        break;
        }
        list_add_rcu(&po->list, elem->list.prev);
        spin_unlock(&offload_lock);
}
EXPORT_SYMBOL(dev_add_offload);

/**
 *      __dev_remove_offload     - remove offload handler
 *      @po: packet offload declaration
 *
 *      Remove a protocol offload handler that was previously added to the
 *      kernel offload handlers by dev_add_offload(). The passed &offload_type
 *      is removed from the kernel lists and can be freed or reused once this
 *      function returns.
 *
 *      The packet type might still be in use by receivers
 *      and must not be freed until after all the CPU's have gone
 *      through a quiescent state.
 */
static void __dev_remove_offload(struct packet_offload *po)
{
        struct list_head *head = &net_hotdata.offload_base;
        struct packet_offload *po1;

        spin_lock(&offload_lock);

        list_for_each_entry(po1, head, list) {
                if (po == po1) {
                        list_del_rcu(&po->list);
                        goto out;
                }
        }

        pr_warn("dev_remove_offload: %p not found\n", po);
out:
        spin_unlock(&offload_lock);
}

/**
 *      dev_remove_offload       - remove packet offload handler
 *      @po: packet offload declaration
 *
 *      Remove a packet offload handler that was previously added to the kernel
 *      offload handlers by dev_add_offload(). The passed &offload_type is
 *      removed from the kernel lists and can be freed or reused once this
 *      function returns.
 *
 *      This call sleeps to guarantee that no CPU is looking at the packet
 *      type after return.
 */
void dev_remove_offload(struct packet_offload *po)
{
        __dev_remove_offload(po);

        synchronize_net();
}
EXPORT_SYMBOL(dev_remove_offload);


int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
{
        struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
        unsigned int offset = skb_gro_offset(skb);
        unsigned int headlen = skb_headlen(skb);
        unsigned int len = skb_gro_len(skb);
        unsigned int delta_truesize;
        unsigned int new_truesize;
        struct sk_buff *lp;
        int segs;

        /* Do not splice page pool based packets w/ non-page pool
         * packets. This can result in reference count issues as page
         * pool pages will not decrement the reference count and will
         * instead be immediately returned to the pool or have frag
         * count decremented.
         */
        if (p->pp_recycle != skb->pp_recycle)
                return -ETOOMANYREFS;

        if (unlikely(p->len + len >= netif_get_gro_max_size(p->dev, p) ||
                     NAPI_GRO_CB(skb)->flush))
                return -E2BIG;

        if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
                if (NAPI_GRO_CB(skb)->proto != IPPROTO_TCP ||
                    (p->protocol == htons(ETH_P_IPV6) &&
                     skb_headroom(p) < sizeof(struct hop_jumbo_hdr)) ||
                    p->encapsulation)
                        return -E2BIG;
        }

        segs = NAPI_GRO_CB(skb)->count;
        lp = NAPI_GRO_CB(p)->last;
        pinfo = skb_shinfo(lp);

        if (headlen <= offset) {
                skb_frag_t *frag;
                skb_frag_t *frag2;
                int i = skbinfo->nr_frags;
                int nr_frags = pinfo->nr_frags + i;

                if (nr_frags > MAX_SKB_FRAGS)
                        goto merge;

                offset -= headlen;
                pinfo->nr_frags = nr_frags;
                skbinfo->nr_frags = 0;

                frag = pinfo->frags + nr_frags;
                frag2 = skbinfo->frags + i;
                do {
                        *--frag = *--frag2;
                } while (--i);

                skb_frag_off_add(frag, offset);
                skb_frag_size_sub(frag, offset);

                /* all fragments truesize : remove (head size + sk_buff) */
                new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
                delta_truesize = skb->truesize - new_truesize;

                skb->truesize = new_truesize;
                skb->len -= skb->data_len;
                skb->data_len = 0;

                NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
                goto done;
        } else if (skb->head_frag) {
                int nr_frags = pinfo->nr_frags;
                skb_frag_t *frag = pinfo->frags + nr_frags;
                struct page *page = virt_to_head_page(skb->head);
                unsigned int first_size = headlen - offset;
                unsigned int first_offset;

                if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
                        goto merge;

                first_offset = skb->data -
                               (unsigned char *)page_address(page) +
                               offset;

                pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;

                skb_frag_fill_page_desc(frag, page, first_offset, first_size);

                memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
                /* We dont need to clear skbinfo->nr_frags here */

                new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
                delta_truesize = skb->truesize - new_truesize;
                skb->truesize = new_truesize;
                NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
                goto done;
        }

merge:
        /* sk ownership - if any - completely transferred to the aggregated packet */
        skb->destructor = NULL;
        skb->sk = NULL;
        delta_truesize = skb->truesize;
        if (offset > headlen) {
                unsigned int eat = offset - headlen;

                skb_frag_off_add(&skbinfo->frags[0], eat);
                skb_frag_size_sub(&skbinfo->frags[0], eat);
                skb->data_len -= eat;
                skb->len -= eat;
                offset = headlen;
        }

        __skb_pull(skb, offset);

        if (NAPI_GRO_CB(p)->last == p)
                skb_shinfo(p)->frag_list = skb;
        else
                NAPI_GRO_CB(p)->last->next = skb;
        NAPI_GRO_CB(p)->last = skb;
        __skb_header_release(skb);
        lp = p;

done:
        NAPI_GRO_CB(p)->count += segs;
        p->data_len += len;
        p->truesize += delta_truesize;
        p->len += len;
        if (lp != p) {
                lp->data_len += len;
                lp->truesize += delta_truesize;
                lp->len += len;
        }
        NAPI_GRO_CB(skb)->same_flow = 1;
        return 0;
}

int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
{
        if (unlikely(p->len + skb->len >= 65536))
                return -E2BIG;

        if (NAPI_GRO_CB(p)->last == p)
                skb_shinfo(p)->frag_list = skb;
        else
                NAPI_GRO_CB(p)->last->next = skb;

        skb_pull(skb, skb_gro_offset(skb));

        NAPI_GRO_CB(p)->last = skb;
        NAPI_GRO_CB(p)->count++;
        p->data_len += skb->len;

        /* sk ownership - if any - completely transferred to the aggregated packet */
        skb->destructor = NULL;
        skb->sk = NULL;
        p->truesize += skb->truesize;
        p->len += skb->len;

        NAPI_GRO_CB(skb)->same_flow = 1;

        return 0;
}


static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
{
        struct list_head *head = &net_hotdata.offload_base;
        struct packet_offload *ptype;
        __be16 type = skb->protocol;
        int err = -ENOENT;

        BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));

        if (NAPI_GRO_CB(skb)->count == 1) {
                skb_shinfo(skb)->gso_size = 0;
                goto out;
        }

        rcu_read_lock();
        list_for_each_entry_rcu(ptype, head, list) {
                if (ptype->type != type || !ptype->callbacks.gro_complete)
                        continue;

                err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
                                         ipv6_gro_complete, inet_gro_complete,
                                         skb, 0);
                break;
        }
        rcu_read_unlock();

        if (err) {
                WARN_ON(&ptype->list == head);
                kfree_skb(skb);
                return;
        }

out:
        gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
}

static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
                                   bool flush_old)
{
        struct list_head *head = &napi->gro_hash[index].list;
        struct sk_buff *skb, *p;

        list_for_each_entry_safe_reverse(skb, p, head, list) {
                if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
                        return;
                skb_list_del_init(skb);
                napi_gro_complete(napi, skb);
                napi->gro_hash[index].count--;
        }

        if (!napi->gro_hash[index].count)
                __clear_bit(index, &napi->gro_bitmask);
}

/* napi->gro_hash[].list contains packets ordered by age.
 * youngest packets at the head of it.
 * Complete skbs in reverse order to reduce latencies.
 */
void napi_gro_flush(struct napi_struct *napi, bool flush_old)
{
        unsigned long bitmask = napi->gro_bitmask;
        unsigned int i, base = ~0U;

        while ((i = ffs(bitmask)) != 0) {
                bitmask >>= i;
                base += i;
                __napi_gro_flush_chain(napi, base, flush_old);
        }
}
EXPORT_SYMBOL(napi_gro_flush);

static unsigned long gro_list_prepare_tc_ext(const struct sk_buff *skb,
                                             const struct sk_buff *p,
                                             unsigned long diffs)
{
#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
        struct tc_skb_ext *skb_ext;
        struct tc_skb_ext *p_ext;

        skb_ext = skb_ext_find(skb, TC_SKB_EXT);
        p_ext = skb_ext_find(p, TC_SKB_EXT);

        diffs |= (!!p_ext) ^ (!!skb_ext);
        if (!diffs && unlikely(skb_ext))
                diffs |= p_ext->chain ^ skb_ext->chain;
#endif
        return diffs;
}

static void gro_list_prepare(const struct list_head *head,
                             const struct sk_buff *skb)
{
        unsigned int maclen = skb->dev->hard_header_len;
        u32 hash = skb_get_hash_raw(skb);
        struct sk_buff *p;

        list_for_each_entry(p, head, list) {
                unsigned long diffs;

                if (hash != skb_get_hash_raw(p)) {
                        NAPI_GRO_CB(p)->same_flow = 0;
                        continue;
                }

                diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
                diffs |= p->vlan_all ^ skb->vlan_all;
                diffs |= skb_metadata_differs(p, skb);
                if (maclen == ETH_HLEN)
                        diffs |= compare_ether_header(skb_mac_header(p),
                                                      skb_mac_header(skb));
                else if (!diffs)
                        diffs = memcmp(skb_mac_header(p),
                                       skb_mac_header(skb),
                                       maclen);

                /* in most common scenarios 'slow_gro' is 0
                 * otherwise we are already on some slower paths
                 * either skip all the infrequent tests altogether or
                 * avoid trying too hard to skip each of them individually
                 */
                if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
                        diffs |= p->sk != skb->sk;
                        diffs |= skb_metadata_dst_cmp(p, skb);
                        diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);

                        diffs |= gro_list_prepare_tc_ext(skb, p, diffs);
                }

                NAPI_GRO_CB(p)->same_flow = !diffs;
        }
}

static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
{
        const struct skb_shared_info *pinfo;
        const skb_frag_t *frag0;
        unsigned int headlen;

        NAPI_GRO_CB(skb)->network_offset = 0;
        NAPI_GRO_CB(skb)->data_offset = 0;
        headlen = skb_headlen(skb);
        NAPI_GRO_CB(skb)->frag0 = skb->data;
        NAPI_GRO_CB(skb)->frag0_len = headlen;
        if (headlen)
                return;

        pinfo = skb_shinfo(skb);
        frag0 = &pinfo->frags[0];

        if (pinfo->nr_frags && skb_frag_page(frag0) &&
            !PageHighMem(skb_frag_page(frag0)) &&
            (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
                NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
                NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
                                                    skb_frag_size(frag0),
                                                    skb->end - skb->tail);
        }
}

static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
{
        struct skb_shared_info *pinfo = skb_shinfo(skb);

        BUG_ON(skb->end - skb->tail < grow);

        memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);

        skb->data_len -= grow;
        skb->tail += grow;

        skb_frag_off_add(&pinfo->frags[0], grow);
        skb_frag_size_sub(&pinfo->frags[0], grow);

        if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
                skb_frag_unref(skb, 0);
                memmove(pinfo->frags, pinfo->frags + 1,
                        --pinfo->nr_frags * sizeof(pinfo->frags[0]));
        }
}

static void gro_try_pull_from_frag0(struct sk_buff *skb)
{
        int grow = skb_gro_offset(skb) - skb_headlen(skb);

        if (grow > 0)
                gro_pull_from_frag0(skb, grow);
}

static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
{
        struct sk_buff *oldest;

        oldest = list_last_entry(head, struct sk_buff, list);

        /* We are called with head length >= MAX_GRO_SKBS, so this is
         * impossible.
         */
        if (WARN_ON_ONCE(!oldest))
                return;

        /* Do not adjust napi->gro_hash[].count, caller is adding a new
         * SKB to the chain.
         */
        skb_list_del_init(oldest);
        napi_gro_complete(napi, oldest);
}

static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{
        u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
        struct gro_list *gro_list = &napi->gro_hash[bucket];
        struct list_head *head = &net_hotdata.offload_base;
        struct packet_offload *ptype;
        __be16 type = skb->protocol;
        struct sk_buff *pp = NULL;
        enum gro_result ret;
        int same_flow;

        if (netif_elide_gro(skb->dev))
                goto normal;

        gro_list_prepare(&gro_list->list, skb);

        rcu_read_lock();
        list_for_each_entry_rcu(ptype, head, list) {
                if (ptype->type == type && ptype->callbacks.gro_receive)
                        goto found_ptype;
        }
        rcu_read_unlock();
        goto normal;

found_ptype:
        skb_set_network_header(skb, skb_gro_offset(skb));
        skb_reset_mac_len(skb);
        BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
        BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
                                        sizeof(u32))); /* Avoid slow unaligned acc */
        *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
        NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
        NAPI_GRO_CB(skb)->count = 1;
        if (unlikely(skb_is_gso(skb))) {
                NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
                /* Only support TCP and non DODGY users. */
                if (!skb_is_gso_tcp(skb) ||
                    (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
                        NAPI_GRO_CB(skb)->flush = 1;
        }

        /* Setup for GRO checksum validation */
        switch (skb->ip_summed) {
        case CHECKSUM_COMPLETE:
                NAPI_GRO_CB(skb)->csum = skb->csum;
                NAPI_GRO_CB(skb)->csum_valid = 1;
                break;
        case CHECKSUM_UNNECESSARY:
                NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
                break;
        }

        pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
                                ipv6_gro_receive, inet_gro_receive,
                                &gro_list->list, skb);

        rcu_read_unlock();

        if (PTR_ERR(pp) == -EINPROGRESS) {
                ret = GRO_CONSUMED;
                goto ok;
        }

        same_flow = NAPI_GRO_CB(skb)->same_flow;
        ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;

        if (pp) {
                skb_list_del_init(pp);
                napi_gro_complete(napi, pp);
                gro_list->count--;
        }

        if (same_flow)
                goto ok;

        if (NAPI_GRO_CB(skb)->flush)
                goto normal;

        if (unlikely(gro_list->count >= MAX_GRO_SKBS))
                gro_flush_oldest(napi, &gro_list->list);
        else
                gro_list->count++;

        /* Must be called before setting NAPI_GRO_CB(skb)->{age|last} */
        gro_try_pull_from_frag0(skb);
        NAPI_GRO_CB(skb)->age = jiffies;
        NAPI_GRO_CB(skb)->last = skb;
        if (!skb_is_gso(skb))
                skb_shinfo(skb)->gso_size = skb_gro_len(skb);
        list_add(&skb->list, &gro_list->list);
        ret = GRO_HELD;
ok:
        if (gro_list->count) {
                if (!test_bit(bucket, &napi->gro_bitmask))
                        __set_bit(bucket, &napi->gro_bitmask);
        } else if (test_bit(bucket, &napi->gro_bitmask)) {
                __clear_bit(bucket, &napi->gro_bitmask);
        }

        return ret;

normal:
        ret = GRO_NORMAL;
        gro_try_pull_from_frag0(skb);
        goto ok;
}

struct packet_offload *gro_find_receive_by_type(__be16 type)
{
        struct list_head *offload_head = &net_hotdata.offload_base;
        struct packet_offload *ptype;

        list_for_each_entry_rcu(ptype, offload_head, list) {
                if (ptype->type != type || !ptype->callbacks.gro_receive)
                        continue;
                return ptype;
        }
        return NULL;
}
EXPORT_SYMBOL(gro_find_receive_by_type);

struct packet_offload *gro_find_complete_by_type(__be16 type)
{
        struct list_head *offload_head = &net_hotdata.offload_base;
        struct packet_offload *ptype;

        list_for_each_entry_rcu(ptype, offload_head, list) {
                if (ptype->type != type || !ptype->callbacks.gro_complete)
                        continue;
                return ptype;
        }
        return NULL;
}
EXPORT_SYMBOL(gro_find_complete_by_type);

static gro_result_t napi_skb_finish(struct napi_struct *napi,
                                    struct sk_buff *skb,
                                    gro_result_t ret)
{
        switch (ret) {
        case GRO_NORMAL:
                gro_normal_one(napi, skb, 1);
                break;

        case GRO_MERGED_FREE:
                if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
                        napi_skb_free_stolen_head(skb);
                else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
                        __kfree_skb(skb);
                else
                        __napi_kfree_skb(skb, SKB_CONSUMED);
                break;

        case GRO_HELD:
        case GRO_MERGED:
        case GRO_CONSUMED:
                break;
        }

        return ret;
}

gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{
        gro_result_t ret;

        skb_mark_napi_id(skb, napi);
        trace_napi_gro_receive_entry(skb);

        skb_gro_reset_offset(skb, 0);

        ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
        trace_napi_gro_receive_exit(ret);

        return ret;
}
EXPORT_SYMBOL(napi_gro_receive);

static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
{
        if (unlikely(skb->pfmemalloc)) {
                consume_skb(skb);
                return;
        }
        __skb_pull(skb, skb_headlen(skb));
        /* restore the reserve we had after netdev_alloc_skb_ip_align() */
        skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
        __vlan_hwaccel_clear_tag(skb);
        skb->dev = napi->dev;
        skb->skb_iif = 0;

        /* eth_type_trans() assumes pkt_type is PACKET_HOST */
        skb->pkt_type = PACKET_HOST;

        skb->encapsulation = 0;
        skb_shinfo(skb)->gso_type = 0;
        skb_shinfo(skb)->gso_size = 0;
        if (unlikely(skb->slow_gro)) {
                skb_orphan(skb);
                skb_ext_reset(skb);
                nf_reset_ct(skb);
                skb->slow_gro = 0;
        }

        napi->skb = skb;
}

struct sk_buff *napi_get_frags(struct napi_struct *napi)
{
        struct sk_buff *skb = napi->skb;

        if (!skb) {
                skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
                if (skb) {
                        napi->skb = skb;
                        skb_mark_napi_id(skb, napi);
                }
        }
        return skb;
}
EXPORT_SYMBOL(napi_get_frags);

static gro_result_t napi_frags_finish(struct napi_struct *napi,
                                      struct sk_buff *skb,
                                      gro_result_t ret)
{
        switch (ret) {
        case GRO_NORMAL:
        case GRO_HELD:
                __skb_push(skb, ETH_HLEN);
                skb->protocol = eth_type_trans(skb, skb->dev);
                if (ret == GRO_NORMAL)
                        gro_normal_one(napi, skb, 1);
                break;

        case GRO_MERGED_FREE:
                if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
                        napi_skb_free_stolen_head(skb);
                else
                        napi_reuse_skb(napi, skb);
                break;

        case GRO_MERGED:
        case GRO_CONSUMED:
                break;
        }

        return ret;
}

/* Upper GRO stack assumes network header starts at gro_offset=0
 * Drivers could call both napi_gro_frags() and napi_gro_receive()
 * We copy ethernet header into skb->data to have a common layout.
 */
static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
{
        struct sk_buff *skb = napi->skb;
        const struct ethhdr *eth;
        unsigned int hlen = sizeof(*eth);

        napi->skb = NULL;

        skb_reset_mac_header(skb);
        skb_gro_reset_offset(skb, hlen);

        if (unlikely(!skb_gro_may_pull(skb, hlen))) {
                eth = skb_gro_header_slow(skb, hlen, 0);
                if (unlikely(!eth)) {
                        net_warn_ratelimited("%s: dropping impossible skb from %s\n",
                                             __func__, napi->dev->name);
                        napi_reuse_skb(napi, skb);
                        return NULL;
                }
        } else {
                eth = (const struct ethhdr *)skb->data;

                if (NAPI_GRO_CB(skb)->frag0 != skb->data)
                        gro_pull_from_frag0(skb, hlen);

                NAPI_GRO_CB(skb)->frag0 += hlen;
                NAPI_GRO_CB(skb)->frag0_len -= hlen;
        }
        __skb_pull(skb, hlen);

        /*
         * This works because the only protocols we care about don't require
         * special handling.
         * We'll fix it up properly in napi_frags_finish()
         */
        skb->protocol = eth->h_proto;

        return skb;
}

gro_result_t napi_gro_frags(struct napi_struct *napi)
{
        gro_result_t ret;
        struct sk_buff *skb = napi_frags_skb(napi);

        trace_napi_gro_frags_entry(skb);

        ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
        trace_napi_gro_frags_exit(ret);

        return ret;
}
EXPORT_SYMBOL(napi_gro_frags);

/* Compute the checksum from gro_offset and return the folded value
 * after adding in any pseudo checksum.
 */
__sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
{
        __wsum wsum;
        __sum16 sum;

        wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);

        /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
        sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
        /* See comments in __skb_checksum_complete(). */
        if (likely(!sum)) {
                if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
                    !skb->csum_complete_sw)
                        netdev_rx_csum_fault(skb->dev, skb);
        }

        NAPI_GRO_CB(skb)->csum = wsum;
        NAPI_GRO_CB(skb)->csum_valid = 1;

        return sum;
}
EXPORT_SYMBOL(__skb_gro_checksum_complete);