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authorHerbert Xu <herbert@gondor.apana.org.au>2006-06-23 13:06:41 +0400
committerDavid S. Miller <davem@davemloft.net>2006-06-23 13:06:41 +0400
commit5b057c6b1a25d57edf2b4d1e956e50936480a9ff (patch)
treee641febd6f562e0ed1198c160ff353ab513f0612 /include/linux/skbuff.h
parent5fa21d821f6972e70942f2c555ec29dde962bdb2 (diff)
downloadlinux-5b057c6b1a25d57edf2b4d1e956e50936480a9ff.tar.xz
[NET]: Avoid allocating skb in skb_pad
First of all it is unnecessary to allocate a new skb in skb_pad since the existing one is not shared. More importantly, our hard_start_xmit interface does not allow a new skb to be allocated since that breaks requeueing. This patch uses pskb_expand_head to expand the existing skb and linearize it if needed. Actually, someone should sift through every instance of skb_pad on a non-linear skb as they do not fit the reasons why this was originally created. Incidentally, this fixes a minor bug when the skb is cloned (tcpdump, TCP, etc.). As it is skb_pad will simply write over a cloned skb. Because of the position of the write it is unlikely to cause problems but still it's best if we don't do it. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/skbuff.h')
-rw-r--r--include/linux/skbuff.h11
1 files changed, 5 insertions, 6 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 66f8819f9568..f8c7eb79a27f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -345,7 +345,7 @@ extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
int newheadroom, int newtailroom,
gfp_t priority);
-extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
+extern int skb_pad(struct sk_buff *skb, int pad);
#define dev_kfree_skb(a) kfree_skb(a)
extern void skb_over_panic(struct sk_buff *skb, int len,
void *here);
@@ -1122,16 +1122,15 @@ static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
*
* Pads up a buffer to ensure the trailing bytes exist and are
* blanked. If the buffer already contains sufficient data it
- * is untouched. Returns the buffer, which may be a replacement
- * for the original, or NULL for out of memory - in which case
- * the original buffer is still freed.
+ * is untouched. Otherwise it is extended. Returns zero on
+ * success. The skb is freed on error.
*/
-static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
+static inline int skb_padto(struct sk_buff *skb, unsigned int len)
{
unsigned int size = skb->len;
if (likely(size >= len))
- return skb;
+ return 0;
return skb_pad(skb, len-size);
}