From bad43ca8325f493dcaa0896c2f036276af059c7e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 19 May 2012 03:02:02 +0000 Subject: [PATCH] net: introduce skb_try_coalesce() Move tcp_try_coalesce() protocol independent part to skb_try_coalesce(). skb_try_coalesce() can be used in IPv4 defrag and IPv6 reassembly, to build optimized skbs (less sk_buff, and possibly less 'headers') skb_try_coalesce() is zero copy, unless the copy can fit in destination header (its a rare case) kfree_skb_partial() is also moved to net/core/skbuff.c and exported, because IPv6 will need it in patch (ipv6: use skb coalescing in reassembly). Signed-off-by: Eric Dumazet Cc: Alexander Duyck Signed-off-by: David S. Miller --- include/linux/skbuff.h | 5 +++ net/core/skbuff.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_input.c | 67 ++------------------------------------- 3 files changed, 94 insertions(+), 64 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index fe37c21..0e50171 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -562,6 +562,11 @@ extern void kfree_skb(struct sk_buff *skb); extern void consume_skb(struct sk_buff *skb); extern void __kfree_skb(struct sk_buff *skb); extern struct kmem_cache *skbuff_head_cache; + +extern void kfree_skb_partial(struct sk_buff *skb, bool head_stolen); +extern bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, + bool *fragstolen, int *delta_truesize); + extern struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int fclone, int node); extern struct sk_buff *build_skb(void *data, unsigned int frag_size); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 7ceb673..016694d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3346,3 +3346,89 @@ void __skb_warn_lro_forwarding(const struct sk_buff *skb) skb->dev->name); } EXPORT_SYMBOL(__skb_warn_lro_forwarding); + +void kfree_skb_partial(struct sk_buff *skb, bool head_stolen) +{ + if (head_stolen) + kmem_cache_free(skbuff_head_cache, skb); + else + __kfree_skb(skb); +} +EXPORT_SYMBOL(kfree_skb_partial); + +/** + * skb_try_coalesce - try to merge skb to prior one + * @to: prior buffer + * @from: buffer to add + * @fragstolen: pointer to boolean + * + */ +bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, + bool *fragstolen, int *delta_truesize) +{ + int i, delta, len = from->len; + + *fragstolen = false; + + if (skb_cloned(to)) + return false; + + if (len <= skb_tailroom(to)) { + BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len)); + *delta_truesize = 0; + return true; + } + + if (skb_has_frag_list(to) || skb_has_frag_list(from)) + return false; + + if (skb_headlen(from) != 0) { + struct page *page; + unsigned int offset; + + if (skb_shinfo(to)->nr_frags + + skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) + return false; + + if (skb_head_is_locked(from)) + return false; + + delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff)); + + page = virt_to_head_page(from->head); + offset = from->data - (unsigned char *)page_address(page); + + skb_fill_page_desc(to, skb_shinfo(to)->nr_frags, + page, offset, skb_headlen(from)); + *fragstolen = true; + } else { + if (skb_shinfo(to)->nr_frags + + skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS) + return false; + + delta = from->truesize - + SKB_TRUESIZE(skb_end_pointer(from) - from->head); + } + + WARN_ON_ONCE(delta < len); + + memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags, + skb_shinfo(from)->frags, + skb_shinfo(from)->nr_frags * sizeof(skb_frag_t)); + skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags; + + if (!skb_cloned(from)) + skb_shinfo(from)->nr_frags = 0; + + /* if the skb is cloned this does nothing since we set nr_frags to 0 */ + for (i = 0; i < skb_shinfo(from)->nr_frags; i++) + skb_frag_ref(from, i); + + to->truesize += delta; + to->len += len; + to->data_len += len; + + *delta_truesize = delta; + return true; +} +EXPORT_SYMBOL(skb_try_coalesce); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index b961ef5..cfa2aa1 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4549,84 +4549,23 @@ static bool tcp_try_coalesce(struct sock *sk, struct sk_buff *from, bool *fragstolen) { - int i, delta, len = from->len; + int delta; *fragstolen = false; - if (tcp_hdr(from)->fin || skb_cloned(to)) + if (tcp_hdr(from)->fin) return false; - - if (len <= skb_tailroom(to)) { - BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len)); - goto merge; - } - - if (skb_has_frag_list(to) || skb_has_frag_list(from)) + if (!skb_try_coalesce(to, from, fragstolen, &delta)) return false; - if (skb_headlen(from) != 0) { - struct page *page; - unsigned int offset; - - if (skb_shinfo(to)->nr_frags + - skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) - return false; - - if (skb_head_is_locked(from)) - return false; - - delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff)); - - page = virt_to_head_page(from->head); - offset = from->data - (unsigned char *)page_address(page); - - skb_fill_page_desc(to, skb_shinfo(to)->nr_frags, - page, offset, skb_headlen(from)); - *fragstolen = true; - } else { - if (skb_shinfo(to)->nr_frags + - skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS) - return false; - - delta = from->truesize - - SKB_TRUESIZE(skb_end_pointer(from) - from->head); - } - - WARN_ON_ONCE(delta < len); - - memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags, - skb_shinfo(from)->frags, - skb_shinfo(from)->nr_frags * sizeof(skb_frag_t)); - skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags; - - if (!skb_cloned(from)) - skb_shinfo(from)->nr_frags = 0; - - /* if the skb is cloned this does nothing since we set nr_frags to 0 */ - for (i = 0; i < skb_shinfo(from)->nr_frags; i++) - skb_frag_ref(from, i); - - to->truesize += delta; atomic_add(delta, &sk->sk_rmem_alloc); sk_mem_charge(sk, delta); - to->len += len; - to->data_len += len; - -merge: NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRCVCOALESCE); TCP_SKB_CB(to)->end_seq = TCP_SKB_CB(from)->end_seq; TCP_SKB_CB(to)->ack_seq = TCP_SKB_CB(from)->ack_seq; return true; } -static void kfree_skb_partial(struct sk_buff *skb, bool head_stolen) -{ - if (head_stolen) - kmem_cache_free(skbuff_head_cache, skb); - else - __kfree_skb(skb); -} - static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); -- 2.7.4