From 5b057c6b1a25d57edf2b4d1e956e50936480a9ff Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 23 Jun 2006 02:06:41 -0700 Subject: [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 Signed-off-by: David S. Miller --- include/linux/skbuff.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'include/linux/skbuff.h') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 66f8819f956..f8c7eb79a27 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); } -- cgit v1.2.3