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/appletalk/ddp.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) (limited to 'net/appletalk') 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(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; - 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; } } -- cgit v1.2.3