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Date: Wed, 4 Apr 2007 18:03:04 +0200
From: Jean Delvare <jdelvare@...e.de>
To: netdev@...r.kernel.org
Subject: Re: [PATCH RFC] Clean up sk_buff walkers
Le Mardi 20 Mars 2007 08:19, Jean Delvare a écrit :
> 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?
Hmm, no comment? The cleanup seems worth the effort, both for source
code readability and binary size.
> Signed-off-by: Jean Delvare <jdelvare@...e.de>
> ---
> net/appletalk/ddp.c | 25 +++++--------
> net/core/datagram.c | 50 ++++++++----------------
> net/core/skbuff.c | 100 +++++++++++++++++--------------------------------
> net/core/user_dma.c | 25 +++++--------
> net/xfrm/xfrm_algo.c | 44 ++++++++--------------
> 5 files changed, 86 insertions(+), 158 deletions(-)
>
> --- linux-2.6.21-rc4.orig/net/core/skbuff.c 2007-03-19
> 09:23:49.000000000 +0100 +++
> linux-2.6.21-rc4/net/core/skbuff.c 2007-03-20 07:12:45.000000000
> +0100 @@ -1081,13 +1081,13 @@ 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;
> memcpy(to, skb->data + offset, copy);
> @@ -1098,11 +1098,9 @@ int skb_copy_bits(const struct sk_buff *
> }
>
> 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;
>
> @@ -1111,8 +1109,8 @@ int skb_copy_bits(const struct sk_buff *
>
> 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)
> @@ -1120,30 +1118,25 @@ int skb_copy_bits(const struct sk_buff *
> 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)
> @@ -1168,12 +1161,12 @@ fault:
> int skb_store_bits(const struct sk_buff *skb, int offset, 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;
> memcpy(skb->data + offset, from, copy);
> @@ -1185,11 +1178,9 @@ int skb_store_bits(const struct sk_buff
>
> 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;
>
> @@ -1197,8 +1188,7 @@ int skb_store_bits(const struct sk_buff
> 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)
> @@ -1206,30 +1196,25 @@ int skb_store_bits(const struct sk_buff
> 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(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_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)
> @@ -1246,8 +1231,8 @@ 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. */
> @@ -1262,11 +1247,9 @@ __wsum skb_checksum(const struct sk_buff
> }
>
> 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;
> @@ -1275,8 +1258,8 @@ __wsum skb_checksum(const struct sk_buff
> 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))
> @@ -1284,31 +1267,26 @@ __wsum skb_checksum(const struct sk_buff
> 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(start <= offset + len);
> + BUG_TRAP(len >= 0);
>
> - 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);
> @@ -1321,8 +1299,8 @@ __wsum skb_checksum(const struct sk_buff
> __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. */
> @@ -1339,11 +1317,9 @@ __wsum skb_copy_and_csum_bits(const stru
> }
>
> 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;
> @@ -1353,9 +1329,8 @@ __wsum skb_copy_and_csum_bits(const stru
> 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))
> @@ -1364,7 +1339,6 @@ __wsum skb_copy_and_csum_bits(const stru
> to += copy;
> pos += copy;
> }
> - start = end;
> }
>
> if (skb_shinfo(skb)->frag_list) {
> @@ -1372,16 +1346,13 @@ __wsum skb_copy_and_csum_bits(const stru
>
> 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)
> @@ -1390,7 +1361,6 @@ __wsum skb_copy_and_csum_bits(const stru
> to += copy;
> pos += copy;
> }
> - start = end;
> }
> }
> BUG_ON(len);
> --- linux-2.6.21-rc4.orig/net/core/datagram.c 2007-02-21
> 08:36:31.000000000 +0100 +++
> linux-2.6.21-rc4/net/core/datagram.c 2007-03-19 21:13:04.000000000
> +0100 @@ -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
>
> /* 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
> 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
> 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(co
> 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(co
> }
>
> 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(co
> 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(co
> 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(co
> to += copy;
> pos += copy;
> }
> - start = end;
> }
> }
> if (!len)
> --- linux-2.6.21-rc4.orig/net/core/user_dma.c 2007-02-21
> 08:36:31.000000000 +0100 +++
> linux-2.6.21-rc4/net/core/user_dma.c 2007-03-20 07:16:27.000000000
> +0100 @@ -49,8 +49,8 @@ int dma_skb_copy_datagram_iovec(struct d
> 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 d
>
> /* 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 d
> 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 d
> 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 d
> goto end;
> offset += copy;
> }
> - start = end;
> }
> }
>
> --- linux-2.6.21-rc4.orig/net/xfrm/xfrm_algo.c 2007-03-19
> 21:34:08.000000000 +0100 +++
> linux-2.6.21-rc4/net/xfrm/xfrm_algo.c 2007-03-19 21:41:59.000000000
> +0100 @@ -532,8 +532,8 @@ EXPORT_SYMBOL_GPL(xfrm_count_enc_support
> 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 *s
> }
>
> 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 *s
> 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 *s
> 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;
> - 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 *s
> return 0;
> offset += copy;
> }
> - start = end;
> }
> }
> BUG_ON(len);
> @@ -617,8 +611,8 @@ EXPORT_SYMBOL_GPL(skb_icv_walk);
> 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) {
> @@ -634,45 +628,39 @@ skb_to_sgvec(struct sk_buff *skb, struct
> }
>
> 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);
> --- linux-2.6.21-rc4.orig/net/appletalk/ddp.c 2007-02-21
> 08:36:30.000000000 +0100 +++
> linux-2.6.21-rc4/net/appletalk/ddp.c 2007-03-19 21:40:07.000000000
> +0100 @@ -937,11 +937,11 @@ static unsigned long atalk_sum_partial(c
> 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
>
> /* 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
> 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;
> }
> }
--
Jean Delvare
Suse L3
-
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