networking: introduce and use skb_put_data()

A common pattern with skb_put() is to just want to memcpy()
some data into the new space, introduce skb_put_data() for
this.

An spatch similar to the one for skb_put_zero() converts many
of the places using it:

    @@
    identifier p, p2;
    expression len, skb, data;
    type t, t2;
    @@
    (
    -p = skb_put(skb, len);
    +p = skb_put_data(skb, data, len);
    |
    -p = (t)skb_put(skb, len);
    +p = skb_put_data(skb, data, len);
    )
    (
    p2 = (t2)p;
    -memcpy(p2, data, len);
    |
    -memcpy(p, data, len);
    )

    @@
    type t, t2;
    identifier p, p2;
    expression skb, data;
    @@
    t *p;
    ...
    (
    -p = skb_put(skb, sizeof(t));
    +p = skb_put_data(skb, data, sizeof(t));
    |
    -p = (t *)skb_put(skb, sizeof(t));
    +p = skb_put_data(skb, data, sizeof(t));
    )
    (
    p2 = (t2)p;
    -memcpy(p2, data, sizeof(*p));
    |
    -memcpy(p, data, sizeof(*p));
    )

    @@
    expression skb, len, data;
    @@
    -memcpy(skb_put(skb, len), data, len);
    +skb_put_data(skb, data, len);

(again, manually post-processed to retain some comments)

Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 2 insertions, 5 deletions

diff --git a/net/sctp/output.c b/net/sctp/output.c
index c339c682675a..febcc350cf00 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -469,8 +469,7 @@ merge:
 				auth = (struct sctp_auth_chunk *)
 							skb_tail_pointer(nskb);
 
-			memcpy(skb_put(nskb, chunk->skb->len), chunk->skb->data,
-			       chunk->skb->len);
+			skb_put_data(nskb, chunk->skb->data, chunk->skb->len);
 
 			pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
 				 chunk,
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index aaac2660aaf7..034e916362cf 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1479,9 +1479,7 @@ void *sctp_addto_chunk(struct sctp_chunk *chunk, int len, const void *data)
 	int padlen = SCTP_PAD4(chunklen) - chunklen;
 
 	padding = skb_put_zero(chunk->skb, padlen);
-	target = skb_put(chunk->skb, len);
-
-	memcpy(target, data, len);
+	target = skb_put_data(chunk->skb, data, len);
 
 	/* Adjust the chunk length field.  */
 	chunk->chunk_hdr->length = htons(chunklen + padlen + len);