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Message-ID: <1337432522.7029.194.camel@edumazet-glaptop>
Date: Sat, 19 May 2012 15:02:02 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Alexander Duyck <alexander.h.duyck@...el.com>
Subject: [PATCH net-next 1/3] net: introduce skb_try_coalesce()
From: Eric Dumazet <edumazet@...gle.com>
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 <edumazet@...gle.com>
Cc: Alexander Duyck <alexander.h.duyck@...el.com>
---
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..ba8a470 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);
--
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