From eefa3906283a2b60a6d02a2cda593a7d7d7946c5 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Thu, 26 Apr 2007 00:44:22 -0700 Subject: [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/core/datagram.c | 50 +++++++++++++++++--------------------------------- 1 file changed, 17 insertions(+), 33 deletions(-) (limited to 'net/core/datagram.c') diff --git a/net/core/datagram.c b/net/core/datagram.c index cb056f47612..e1afa767944 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(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_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(start <= offset + len); + BUG_TRAP(len >= 0); - 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) -- cgit v1.2.3