From eefa3906283a2b60a6d02a2cda593a7d7d7946c5 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Thu, 26 Apr 2007 00:44:22 -0700 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- net/appletalk/ddp.c | 25 ++++----- net/core/datagram.c | 50 ++++++------------ net/core/skbuff.c | 122 +++++++++++++++---------------------------- net/core/user_dma.c | 25 ++++----- net/xfrm/xfrm_algo.c | 22 +++----- 5 files changed, 86 insertions(+), 158 deletions(-) diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c index f6a92a0b7aa6..16eda21fb38c 100644 --- a/net/appletalk/ddp.c +++ b/net/appletalk/ddp.c @@ -937,11 +937,11 @@ static unsigned long atalk_sum_partial(const unsigned char *data, static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset, int len, unsigned long sum) { - int start = skb_headlen(skb); + int end = skb_headlen(skb); int i, copy; /* checksum stuff in header space */ - if ( (copy = start - offset) > 0) { + if ((copy = end - offset) > 0) { if (copy > len) copy = len; sum = atalk_sum_partial(skb->data + offset, copy, sum); @@ -953,11 +953,9 @@ static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset, /* checksum stuff in frags */ 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; skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; @@ -965,36 +963,31 @@ static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset, if (copy > len) copy = len; vaddr = kmap_skb_frag(frag); - sum = atalk_sum_partial(vaddr + frag->page_offset + - offset - start, copy, sum); + sum = atalk_sum_partial(vaddr + frag->page_offset, + copy, sum); kunmap_skb_frag(vaddr); if (!(len -= copy)) return sum; 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; - sum = atalk_sum_skb(list, offset - start, - copy, sum); + sum = atalk_sum_skb(list, 0, copy, sum); if ((len -= copy) == 0) return sum; offset += copy; } - start = end; } } diff --git a/net/core/datagram.c b/net/core/datagram.c index cb056f476126..e1afa7679445 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -247,8 +247,8 @@ EXPORT_SYMBOL(skb_kill_datagram); int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset, struct iovec *to, int len) { - int start = skb_headlen(skb); - int i, copy = start - offset; + int end = skb_headlen(skb); + int i, copy = end - offset; /* Copy header. */ if (copy > 0) { @@ -263,11 +263,9 @@ int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset, /* Copy paged appendix. Hmm... why does this look so complicated? */ 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) { int err; u8 *vaddr; @@ -277,8 +275,8 @@ int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset, if (copy > len) copy = len; vaddr = kmap(page); - err = memcpy_toiovec(to, vaddr + frag->page_offset + - offset - start, copy); + err = memcpy_toiovec(to, vaddr + frag->page_offset, + copy); kunmap(page); if (err) goto fault; @@ -286,30 +284,24 @@ int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset, 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; - if (skb_copy_datagram_iovec(list, - offset - start, - to, copy)) + if (skb_copy_datagram_iovec(list, 0, to, copy)) goto fault; if ((len -= copy) == 0) return 0; offset += copy; } - start = end; } } if (!len) @@ -323,9 +315,9 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, u8 __user *to, int len, __wsum *csump) { - int start = skb_headlen(skb); + int end = skb_headlen(skb); int pos = 0; - int i, copy = start - offset; + int i, copy = end - offset; /* Copy header. */ if (copy > 0) { @@ -344,11 +336,9 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, } 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) { __wsum csum2; int err = 0; @@ -360,8 +350,7 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, copy = len; vaddr = kmap(page); csum2 = csum_and_copy_to_user(vaddr + - frag->page_offset + - offset - start, + frag->page_offset, to, copy, 0, &err); kunmap(page); if (err) @@ -373,24 +362,20 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, to += 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 = 0; if (copy > len) copy = len; - if (skb_copy_and_csum_datagram(list, - offset - start, + if (skb_copy_and_csum_datagram(list, 0, to, copy, &csum2)) goto fault; @@ -401,7 +386,6 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, to += copy; pos += copy; } - start = end; } } if (!len) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 142257307fa2..32f087b5233e 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1045,13 +1045,13 @@ unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta) 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(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_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 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) 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(len >= 0); - BUG_TRAP(start <= offset + len); - - 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(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) { __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(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) { __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(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; - 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(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; - 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); diff --git a/net/core/user_dma.c b/net/core/user_dma.c index 0ad1cd57bc39..89241cdeea3f 100644 --- a/net/core/user_dma.c +++ b/net/core/user_dma.c @@ -49,8 +49,8 @@ int dma_skb_copy_datagram_iovec(struct dma_chan *chan, struct sk_buff *skb, int offset, struct iovec *to, size_t len, struct dma_pinned_list *pinned_list) { - int start = skb_headlen(skb); - int i, copy = start - offset; + int end = skb_headlen(skb); + int i, copy = end - offset; dma_cookie_t cookie = 0; /* Copy header. */ @@ -69,11 +69,9 @@ int dma_skb_copy_datagram_iovec(struct dma_chan *chan, /* Copy paged appendix. Hmm... why does this look so complicated? */ 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; copy = end - offset; if ((copy = end - offset) > 0) { skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; @@ -82,8 +80,8 @@ int dma_skb_copy_datagram_iovec(struct dma_chan *chan, if (copy > len) copy = len; - cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page, - frag->page_offset + offset - start, copy); + cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, + page, frag->page_offset, copy); if (cookie < 0) goto fault; len -= copy; @@ -91,25 +89,21 @@ int dma_skb_copy_datagram_iovec(struct dma_chan *chan, goto end; 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; copy = end - offset; if (copy > 0) { if (copy > len) copy = len; cookie = dma_skb_copy_datagram_iovec(chan, list, - offset - start, to, copy, - pinned_list); + 0, to, copy, pinned_list); if (cookie < 0) goto fault; len -= copy; @@ -117,7 +111,6 @@ int dma_skb_copy_datagram_iovec(struct dma_chan *chan, goto end; offset += copy; } - start = end; } } diff --git a/net/xfrm/xfrm_algo.c b/net/xfrm/xfrm_algo.c index 6249a9405bb8..be529c4241a6 100644 --- a/net/xfrm/xfrm_algo.c +++ b/net/xfrm/xfrm_algo.c @@ -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);