net-gro: restore frag0 optimization
Main difference between napi_frags_skb() and napi_gro_receive() is that the later is called while ethernet header was already pulled by the NIC driver (eth_type_trans() was called before napi_gro_receive()) Jerry Chu in commit299603e837("net-gro: Prepare GRO stack for the upcoming tunneling support") tried to remove this difference by calling eth_type_trans() from napi_frags_skb() instead of doing this later from napi_frags_finish() Goal was that napi_gro_complete() could call ptype->callbacks.gro_complete(skb, 0) (offset of first network header = 0) Also, xxx_gro_receive() handlers all use off = skb_gro_offset(skb) to point to their own header, for the current skb and ones held in gro_list Problem is this cleanup work defeated the frag0 optimization: It turns out the consecutive pskb_may_pull() calls are too expensive. This patch brings back the frag0 stuff in napi_frags_skb(). As all skb have their mac header in skb head, we no longer need skb_gro_mac_header() Reported-by: Michal Schmidt <mschmidt@redhat.com> Fixes:299603e837("net-gro: Prepare GRO stack for the upcoming tunneling support") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jerry Chu <hkchu@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
David S. Miller
parent
bf39b4247b
commit
a50e233c50
2 changed files with 64 additions and 37 deletions
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@ -2014,11 +2014,6 @@ static inline void *skb_gro_header_slow(struct sk_buff *skb, unsigned int hlen,
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return skb->data + offset;
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}
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static inline void *skb_gro_mac_header(struct sk_buff *skb)
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{
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return NAPI_GRO_CB(skb)->frag0 ?: skb_mac_header(skb);
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}
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static inline void *skb_gro_network_header(struct sk_buff *skb)
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{
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return (NAPI_GRO_CB(skb)->frag0 ?: skb->data) +
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@ -3833,10 +3833,10 @@ static void gro_list_prepare(struct napi_struct *napi, struct sk_buff *skb)
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diffs |= p->vlan_tci ^ skb->vlan_tci;
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if (maclen == ETH_HLEN)
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diffs |= compare_ether_header(skb_mac_header(p),
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skb_gro_mac_header(skb));
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skb_mac_header(skb));
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else if (!diffs)
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diffs = memcmp(skb_mac_header(p),
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skb_gro_mac_header(skb),
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skb_mac_header(skb),
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maclen);
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NAPI_GRO_CB(p)->same_flow = !diffs;
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}
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@ -3859,6 +3859,27 @@ static void skb_gro_reset_offset(struct sk_buff *skb)
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}
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}
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static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
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{
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struct skb_shared_info *pinfo = skb_shinfo(skb);
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BUG_ON(skb->end - skb->tail < grow);
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memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
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skb->data_len -= grow;
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skb->tail += grow;
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pinfo->frags[0].page_offset += grow;
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skb_frag_size_sub(&pinfo->frags[0], grow);
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if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
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skb_frag_unref(skb, 0);
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memmove(pinfo->frags, pinfo->frags + 1,
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--pinfo->nr_frags * sizeof(pinfo->frags[0]));
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}
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}
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static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
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{
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struct sk_buff **pp = NULL;
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@ -3867,6 +3888,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
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struct list_head *head = &offload_base;
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int same_flow;
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enum gro_result ret;
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int grow;
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if (!(skb->dev->features & NETIF_F_GRO))
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goto normal;
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@ -3874,7 +3896,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
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if (skb_is_gso(skb) || skb_has_frag_list(skb))
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goto normal;
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skb_gro_reset_offset(skb);
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gro_list_prepare(napi, skb);
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NAPI_GRO_CB(skb)->csum = skb->csum; /* Needed for CHECKSUM_COMPLETE */
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@ -3938,27 +3959,9 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
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ret = GRO_HELD;
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pull:
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if (skb_headlen(skb) < skb_gro_offset(skb)) {
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int grow = skb_gro_offset(skb) - skb_headlen(skb);
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BUG_ON(skb->end - skb->tail < grow);
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memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
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skb->tail += grow;
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skb->data_len -= grow;
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skb_shinfo(skb)->frags[0].page_offset += grow;
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skb_frag_size_sub(&skb_shinfo(skb)->frags[0], grow);
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if (unlikely(!skb_frag_size(&skb_shinfo(skb)->frags[0]))) {
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skb_frag_unref(skb, 0);
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memmove(skb_shinfo(skb)->frags,
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skb_shinfo(skb)->frags + 1,
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--skb_shinfo(skb)->nr_frags * sizeof(skb_frag_t));
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}
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}
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grow = skb_gro_offset(skb) - skb_headlen(skb);
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if (grow > 0)
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gro_pull_from_frag0(skb, grow);
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ok:
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return ret;
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@ -4026,6 +4029,8 @@ gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
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{
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trace_napi_gro_receive_entry(skb);
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skb_gro_reset_offset(skb);
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return napi_skb_finish(dev_gro_receive(napi, skb), skb);
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}
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EXPORT_SYMBOL(napi_gro_receive);
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@ -4054,12 +4059,16 @@ struct sk_buff *napi_get_frags(struct napi_struct *napi)
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}
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EXPORT_SYMBOL(napi_get_frags);
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static gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *skb,
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static gro_result_t napi_frags_finish(struct napi_struct *napi,
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struct sk_buff *skb,
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gro_result_t ret)
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{
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switch (ret) {
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case GRO_NORMAL:
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if (netif_receive_skb_internal(skb))
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case GRO_HELD:
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__skb_push(skb, ETH_HLEN);
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skb->protocol = eth_type_trans(skb, skb->dev);
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if (ret == GRO_NORMAL && netif_receive_skb_internal(skb))
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ret = GRO_DROP;
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break;
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@ -4068,7 +4077,6 @@ static gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *
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napi_reuse_skb(napi, skb);
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break;
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case GRO_HELD:
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case GRO_MERGED:
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break;
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}
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@ -4076,17 +4084,41 @@ static gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *
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return ret;
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}
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/* Upper GRO stack assumes network header starts at gro_offset=0
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* Drivers could call both napi_gro_frags() and napi_gro_receive()
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* We copy ethernet header into skb->data to have a common layout.
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*/
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static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
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{
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struct sk_buff *skb = napi->skb;
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const struct ethhdr *eth;
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unsigned int hlen = sizeof(*eth);
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napi->skb = NULL;
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if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr)))) {
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skb_reset_mac_header(skb);
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skb_gro_reset_offset(skb);
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eth = skb_gro_header_fast(skb, 0);
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if (unlikely(skb_gro_header_hard(skb, hlen))) {
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eth = skb_gro_header_slow(skb, hlen, 0);
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if (unlikely(!eth)) {
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napi_reuse_skb(napi, skb);
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return NULL;
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}
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skb->protocol = eth_type_trans(skb, skb->dev);
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} else {
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gro_pull_from_frag0(skb, hlen);
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NAPI_GRO_CB(skb)->frag0 += hlen;
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NAPI_GRO_CB(skb)->frag0_len -= hlen;
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}
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__skb_pull(skb, hlen);
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/*
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* This works because the only protocols we care about don't require
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* special handling.
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* We'll fix it up properly in napi_frags_finish()
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*/
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skb->protocol = eth->h_proto;
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return skb;
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}
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