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author | Jean Delvare <jdelvare@suse.de> | 2007-04-26 07:44:22 (GMT) |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2007-04-26 07:44:22 (GMT) |
commit | eefa3906283a2b60a6d02a2cda593a7d7d7946c5 (patch) | |
tree | a4e1f3b8dca04b8dff3cd99dc43f771f798558fb /net/core/skbuff.c | |
parent | 28d8909bc790d936ce33f4402adf7577533bbd4b (diff) | |
download | linux-fsl-qoriq-eefa3906283a2b60a6d02a2cda593a7d7d7946c5.tar.xz |
[NET]: Clean up sk_buff walkers.
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>
Diffstat (limited to 'net/core/skbuff.c')
-rw-r--r-- | net/core/skbuff.c | 122 |
1 files changed, 43 insertions, 79 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 1422573..32f087b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1045,13 +1045,13 @@ pull_pages: int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) { int i, copy; - int start = skb_headlen(skb); + int end = skb_headlen(skb); if (offset > (int)skb->len - len) goto fault; /* Copy header. */ - if ((copy = start - offset) > 0) { + if ((copy = end - offset) > 0) { if (copy > len) copy = len; skb_copy_from_linear_data_offset(skb, offset, to, copy); @@ -1062,11 +1062,9 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) } 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) { u8 *vaddr; @@ -1075,8 +1073,8 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]); memcpy(to, - vaddr + skb_shinfo(skb)->frags[i].page_offset+ - offset - start, copy); + vaddr + skb_shinfo(skb)->frags[i].page_offset, + copy); kunmap_skb_frag(vaddr); if ((len -= copy) == 0) @@ -1084,30 +1082,25 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) offset += copy; to += 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(start <= offset + len); + BUG_TRAP(len >= 0); - end = start + list->len; + end = offset + list->len; if ((copy = end - offset) > 0) { if (copy > len) copy = len; - if (skb_copy_bits(list, offset - start, - to, copy)) + if (skb_copy_bits(list, 0, to, copy)) goto fault; if ((len -= copy) == 0) return 0; offset += copy; to += copy; } - start = end; } } if (!len) @@ -1132,12 +1125,12 @@ fault: int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) { int i, copy; - int start = skb_headlen(skb); + int end = skb_headlen(skb); if (offset > (int)skb->len - len) goto fault; - if ((copy = start - offset) > 0) { + if ((copy = end - offset) > 0) { if (copy > len) copy = len; skb_copy_to_linear_data_offset(skb, offset, from, copy); @@ -1149,11 +1142,9 @@ int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; - int end; - - BUG_TRAP(start <= offset + len); + BUG_TRAP(len >= 0); - end = start + frag->size; + end = offset + frag->size; if ((copy = end - offset) > 0) { u8 *vaddr; @@ -1161,8 +1152,7 @@ int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) copy = len; vaddr = kmap_skb_frag(frag); - memcpy(vaddr + frag->page_offset + offset - start, - from, copy); + memcpy(vaddr + frag->page_offset, from, copy); kunmap_skb_frag(vaddr); if ((len -= copy) == 0) @@ -1170,30 +1160,25 @@ int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) offset += copy; from += 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; - if (skb_store_bits(list, offset - start, - from, copy)) + if (skb_store_bits(list, 0, from, copy)) goto fault; if ((len -= copy) == 0) return 0; offset += copy; from += copy; } - start = end; } } if (!len) @@ -1210,8 +1195,8 @@ EXPORT_SYMBOL(skb_store_bits); __wsum skb_checksum(const struct sk_buff *skb, int offset, int len, __wsum csum) { - int start = skb_headlen(skb); - int i, copy = start - offset; + int end = skb_headlen(skb); + int i, copy = end - offset; int pos = 0; /* Checksum header. */ @@ -1226,11 +1211,9 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, } for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { - int end; - - BUG_TRAP(start <= offset + len); + BUG_TRAP(len >= 0); - end = start + skb_shinfo(skb)->frags[i].size; + end = offset + skb_shinfo(skb)->frags[i].size; if ((copy = end - offset) > 0) { __wsum csum2; u8 *vaddr; @@ -1239,8 +1222,8 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, if (copy > len) copy = len; vaddr = kmap_skb_frag(frag); - csum2 = csum_partial(vaddr + frag->page_offset + - offset - start, copy, 0); + csum2 = csum_partial(vaddr + frag->page_offset, + copy, 0); kunmap_skb_frag(vaddr); csum = csum_block_add(csum, csum2, pos); if (!(len -= copy)) @@ -1248,31 +1231,26 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, offset += copy; pos += 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) { __wsum csum2; if (copy > len) copy = len; - csum2 = skb_checksum(list, offset - start, - copy, 0); + csum2 = skb_checksum(list, 0, copy, 0); csum = csum_block_add(csum, csum2, pos); if ((len -= copy) == 0) return csum; offset += copy; pos += copy; } - start = end; } } BUG_ON(len); @@ -1285,8 +1263,8 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to, int len, __wsum csum) { - int start = skb_headlen(skb); - int i, copy = start - offset; + int end = skb_headlen(skb); + int i, copy = end - offset; int pos = 0; /* Copy header. */ @@ -1303,11 +1281,9 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, } for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { - int end; - - BUG_TRAP(start <= offset + len); + BUG_TRAP(len >= 0); - end = start + skb_shinfo(skb)->frags[i].size; + end = offset + skb_shinfo(skb)->frags[i].size; if ((copy = end - offset) > 0) { __wsum csum2; u8 *vaddr; @@ -1317,9 +1293,8 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, copy = len; vaddr = kmap_skb_frag(frag); csum2 = csum_partial_copy_nocheck(vaddr + - frag->page_offset + - offset - start, to, - copy, 0); + frag->page_offset, + to, copy, 0); kunmap_skb_frag(vaddr); csum = csum_block_add(csum, csum2, pos); if (!(len -= copy)) @@ -1328,7 +1303,6 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, to += copy; pos += copy; } - start = end; } if (skb_shinfo(skb)->frag_list) { @@ -1336,16 +1310,13 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, for (; list; list = list->next) { __wsum csum2; - int end; - - BUG_TRAP(start <= offset + len); + BUG_TRAP(len >= 0); - end = start + list->len; + end = offset + list->len; if ((copy = end - offset) > 0) { if (copy > len) copy = len; - csum2 = skb_copy_and_csum_bits(list, - offset - start, + csum2 = skb_copy_and_csum_bits(list, 0, to, copy, 0); csum = csum_block_add(csum, csum2, pos); if ((len -= copy) == 0) @@ -1354,7 +1325,6 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, to += copy; pos += copy; } - start = end; } } BUG_ON(len); @@ -2026,8 +1996,8 @@ void __init skb_init(void) int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) { - int start = skb_headlen(skb); - int i, copy = start - offset; + int end = skb_headlen(skb); + int i, copy = end - offset; int elt = 0; if (copy > 0) { @@ -2043,45 +2013,39 @@ skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) } 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]; if (copy > len) copy = len; sg[elt].page = frag->page; - sg[elt].offset = frag->page_offset+offset-start; + sg[elt].offset = frag->page_offset; sg[elt].length = copy; elt++; if (!(len -= copy)) return elt; 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(start <= offset + len); + BUG_TRAP(len >= 0); - end = start + list->len; + end = offset + list->len; if ((copy = end - offset) > 0) { if (copy > len) copy = len; - elt += skb_to_sgvec(list, sg+elt, offset - start, copy); + elt += skb_to_sgvec(list, sg+elt, 0, copy); if ((len -= copy) == 0) return elt; offset += copy; } - start = end; } } BUG_ON(len); |