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[NET]: Clean up sk_buff walkers.

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I noticed recently that, in skb_checksum(), "offset" and "start" are
essentially the same thing and have the same value throughout the
function, despite being computed differently. Using a single variable
allows some cleanups and makes the skb_checksum() function smaller,
more readable, and presumably marginally faster.

We appear to have many other "sk_buff walker" functions built on the
exact same model, so the cleanup applies to them, too. Here is a list
of the functions I found to be affected:

net/appletalk/ddp.c:atalk_sum_skb()
net/core/datagram.c:skb_copy_datagram_iovec()
net/core/datagram.c:skb_copy_and_csum_datagram()
net/core/skbuff.c:skb_copy_bits()
net/core/skbuff.c:skb_store_bits()
net/core/skbuff.c:skb_checksum()
net/core/skbuff.c:skb_copy_and_csum_bit()
net/core/user_dma.c:dma_skb_copy_datagram_iovec()
net/xfrm/xfrm_algo.c:skb_icv_walk()
net/xfrm/xfrm_algo.c:skb_to_sgvec()

OTOH, I admit I'm a bit surprised, the cleanup is rather obvious so I'm
really wondering if I am missing something. Can anyone please comment
on this?

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jean Delvare
2007-04-26 00:44:22 -07:00
committed by David S. Miller
parent 28d8909bc7
commit eefa390628
5 changed files with 86 additions and 158 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
net/xfrm/xfrm_algo.c
View File

@@ -532,8 +532,8 @@ EXPORT_SYMBOL_GPL(xfrm_count_enc_supported);
int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
int offset, int len, icv_update_fn_t icv_update)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
int end = skb_headlen(skb);
int i, copy = end - offset;
int err;
struct scatterlist sg;
@@ -556,11 +556,9 @@ int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
}
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
BUG_TRAP(len >= 0);
BUG_TRAP(start <= offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
end = offset + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
@@ -568,7 +566,7 @@ int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
copy = len;
sg.page = frag->page;
sg.offset = frag->page_offset + offset-start;
sg.offset = frag->page_offset;
sg.length = copy;
err = icv_update(desc, &sg, copy);
@@ -579,22 +577,19 @@ int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
return 0;
offset += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
int end;
BUG_TRAP(len >= 0);
BUG_TRAP(start <= offset + len);
end = start + list->len;
end = offset + list->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
err = skb_icv_walk(list, desc, offset-start,
err = skb_icv_walk(list, desc, 0,
copy, icv_update);
if (unlikely(err))
return err;
@@ -602,7 +597,6 @@ int skb_icv_walk(const struct sk_buff *skb, struct hash_desc *desc,
return 0;
offset += copy;
}
start = end;
}
}
BUG_ON(len);