dccp: constify dccp_make_response() socket argument

Like tcp_make_synack() the only time we might change the socket is
when calling sock_wmalloc(), which is using atomic operation to
update sk->sk_wmem_alloc

Also use MAX_DCCP_HEADER as both IPv4/IPv6 use this value for max_header.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index bebc735f5afc0fd9993a2a6ddc4074dcaa5b1559..31e96df500d12a5dbde06c08992ce134444183df 100644 (file)
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -293,7 +293,7 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
 void dccp_destroy_sock(struct sock *sk);
 
 void dccp_close(struct sock *sk, long timeout);
-struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
+struct sk_buff *dccp_make_response(const struct sock *sk, struct dst_entry *dst,
                                   struct request_sock *req);
 
 int dccp_connect(struct sock *sk);

diff --git a/net/dccp/output.c b/net/dccp/output.c
index 0248e8a3460c829bf8da8b47b8b7a525f0b85473..4ce912e691d03e925e3fef59d53b0724bd13ce83 100644 (file)
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -390,7 +390,7 @@ int dccp_retransmit_skb(struct sock *sk)
        return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC));
 }
 
-struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
+struct sk_buff *dccp_make_response(const struct sock *sk, struct dst_entry *dst,
                                   struct request_sock *req)
 {
        struct dccp_hdr *dh;
@@ -398,13 +398,18 @@ struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
        const u32 dccp_header_size = sizeof(struct dccp_hdr) +
                                     sizeof(struct dccp_hdr_ext) +
                                     sizeof(struct dccp_hdr_response);
-       struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1,
-                                          GFP_ATOMIC);
-       if (skb == NULL)
+       struct sk_buff *skb;
+
+       /* sk is marked const to clearly express we dont hold socket lock.
+        * sock_wmalloc() will atomically change sk->sk_wmem_alloc,
+        * it is safe to promote sk to non const.
+        */
+       skb = sock_wmalloc((struct sock *)sk, MAX_DCCP_HEADER, 1,
+                          GFP_ATOMIC);
+       if (!skb)
                return NULL;
 
-       /* Reserve space for headers. */
-       skb_reserve(skb, sk->sk_prot->max_header);
+       skb_reserve(skb, MAX_DCCP_HEADER);
 
        skb_dst_set(skb, dst_clone(dst));