sctp: define sctp_packet_gso_append to build GSO frames

Now sctp GSO uses skb_gro_receive() to append the data into head
skb frag_list. However it actually only needs very few code from
skb_gro_receive(). Besides, NAPI_GRO_CB has to be set while most
of its members are not needed here.

This patch is to add sctp_packet_gso_append() to build GSO frames
instead of skb_gro_receive(), and it would avoid many unnecessary
checks and make the code clearer.

Note that sctp will use page frags instead of frag_list to build
GSO frames in another patch. But it may take time, as sctp's GSO
frames may have different size. skb_segment() can only split it
into the frags with the same size, which would break the border
of sctp chunks.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index ebf809eed33add7905ddd13abf98712a833ae0e0..dbe1b911a24d31e920f4c31d3c945857b760424b 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1133,6 +1133,11 @@ struct sctp_input_cb {
 };
 #define SCTP_INPUT_CB(__skb)   ((struct sctp_input_cb *)&((__skb)->cb[0]))
 
+struct sctp_output_cb {
+       struct sk_buff *last;
+};
+#define SCTP_OUTPUT_CB(__skb)  ((struct sctp_output_cb *)&((__skb)->cb[0]))
+
 static inline const struct sk_buff *sctp_gso_headskb(const struct sk_buff *skb)
 {
        const struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;

diff --git a/net/sctp/output.c b/net/sctp/output.c
index e672dee302c7092433a64ed3ed8bfcd183e1f9c8..7f849b01ec8e6767b851145bbf3d7086cc1cef23 100644 (file)
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -409,6 +409,21 @@ static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk)
        refcount_inc(&sk->sk_wmem_alloc);
 }
 
+static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb)
+{
+       if (SCTP_OUTPUT_CB(head)->last == head)
+               skb_shinfo(head)->frag_list = skb;
+       else
+               SCTP_OUTPUT_CB(head)->last->next = skb;
+       SCTP_OUTPUT_CB(head)->last = skb;
+
+       head->truesize += skb->truesize;
+       head->data_len += skb->len;
+       head->len += skb->len;
+
+       __skb_header_release(skb);
+}
+
 static int sctp_packet_pack(struct sctp_packet *packet,
                            struct sk_buff *head, int gso, gfp_t gfp)
 {
@@ -422,7 +437,7 @@ static int sctp_packet_pack(struct sctp_packet *packet,
 
        if (gso) {
                skb_shinfo(head)->gso_type = sk->sk_gso_type;
-               NAPI_GRO_CB(head)->last = head;
+               SCTP_OUTPUT_CB(head)->last = head;
        } else {
                nskb = head;
                pkt_size = packet->size;
@@ -503,15 +518,8 @@ merge:
                                         &packet->chunk_list);
                }
 
-               if (gso) {
-                       if (skb_gro_receive(&head, nskb)) {
-                               kfree_skb(nskb);
-                               return 0;
-                       }
-                       if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >=
-                                        sk->sk_gso_max_segs))
-                               return 0;
-               }
+               if (gso)
+                       sctp_packet_gso_append(head, nskb);
 
                pkt_count++;
        } while (!list_empty(&packet->chunk_list));