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/user_dma.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) (limited to 'net/core/user_dma.c') 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(start <= offset + len); + BUG_TRAP(len >= 0); - 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; } } -- cgit v1.2.3