diff options
| -rw-r--r-- | include/linux/skbuff.h | 24 | ||||
| -rw-r--r-- | net/core/skbuff.c | 106 |
2 files changed, 86 insertions, 44 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index ad7cc22bd42..7e631a54257 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -956,15 +956,16 @@ static inline void skb_reserve(struct sk_buff *skb, int len) #define NET_IP_ALIGN 2 #endif -extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc); +extern int ___pskb_trim(struct sk_buff *skb, unsigned int len); static inline void __skb_trim(struct sk_buff *skb, unsigned int len) { - if (!skb->data_len) { - skb->len = len; - skb->tail = skb->data + len; - } else - ___pskb_trim(skb, len, 0); + if (unlikely(skb->data_len)) { + WARN_ON(1); + return; + } + skb->len = len; + skb->tail = skb->data + len; } /** @@ -974,6 +975,7 @@ static inline void __skb_trim(struct sk_buff *skb, unsigned int len) * * Cut the length of a buffer down by removing data from the tail. If * the buffer is already under the length specified it is not modified. + * The skb must be linear. */ static inline void skb_trim(struct sk_buff *skb, unsigned int len) { @@ -984,12 +986,10 @@ static inline void skb_trim(struct sk_buff *skb, unsigned int len) static inline int __pskb_trim(struct sk_buff *skb, unsigned int len) { - if (!skb->data_len) { - skb->len = len; - skb->tail = skb->data+len; - return 0; - } - return ___pskb_trim(skb, len, 1); + if (skb->data_len) + return ___pskb_trim(skb, len); + __skb_trim(skb, len); + return 0; } static inline int pskb_trim(struct sk_buff *skb, unsigned int len) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 09efe62fe01..a26b2348bc9 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -243,11 +243,11 @@ nodata: } -static void skb_drop_fraglist(struct sk_buff *skb) +static void skb_drop_list(struct sk_buff **listp) { - struct sk_buff *list = skb_shinfo(skb)->frag_list; + struct sk_buff *list = *listp; - skb_shinfo(skb)->frag_list = NULL; + *listp = NULL; do { struct sk_buff *this = list; @@ -256,6 +256,11 @@ static void skb_drop_fraglist(struct sk_buff *skb) } while (list); } +static inline void skb_drop_fraglist(struct sk_buff *skb) +{ + skb_drop_list(&skb_shinfo(skb)->frag_list); +} + static void skb_clone_fraglist(struct sk_buff *skb) { struct sk_buff *list; @@ -777,49 +782,86 @@ struct sk_buff *skb_pad(struct sk_buff *skb, int pad) return nskb; } -/* Trims skb to length len. It can change skb pointers, if "realloc" is 1. - * If realloc==0 and trimming is impossible without change of data, - * it is BUG(). +/* Trims skb to length len. It can change skb pointers. */ -int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc) +int ___pskb_trim(struct sk_buff *skb, unsigned int len) { + struct sk_buff **fragp; + struct sk_buff *frag; int offset = skb_headlen(skb); int nfrags = skb_shinfo(skb)->nr_frags; int i; + int err; - for (i = 0; i < nfrags; i++) { + if (skb_cloned(skb) && + unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))) + return err; + + i = 0; + if (offset >= len) + goto drop_pages; + + for (; i < nfrags; i++) { int end = offset + skb_shinfo(skb)->frags[i].size; - if (end > len) { - if (skb_cloned(skb)) { - BUG_ON(!realloc); - if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) - return -ENOMEM; - } - if (len <= offset) { - put_page(skb_shinfo(skb)->frags[i].page); - skb_shinfo(skb)->nr_frags--; - } else { - skb_shinfo(skb)->frags[i].size = len - offset; - } + + if (end < len) { + offset = end; + continue; } - offset = end; + + skb_shinfo(skb)->frags[i++].size = len - offset; + +drop_pages: + skb_shinfo(skb)->nr_frags = i; + + for (; i < nfrags; i++) + put_page(skb_shinfo(skb)->frags[i].page); + + if (skb_shinfo(skb)->frag_list) + skb_drop_fraglist(skb); + goto done; + } + + for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp); + fragp = &frag->next) { + int end = offset + frag->len; + + if (skb_shared(frag)) { + struct sk_buff *nfrag; + + nfrag = skb_clone(frag, GFP_ATOMIC); + if (unlikely(!nfrag)) + return -ENOMEM; + + nfrag->next = frag->next; + kfree_skb(frag); + frag = nfrag; + *fragp = frag; + } + + if (end < len) { + offset = end; + continue; + } + + if (end > len && + unlikely((err = pskb_trim(frag, len - offset)))) + return err; + + if (frag->next) + skb_drop_list(&frag->next); + break; } - if (offset < len) { +done: + if (len > skb_headlen(skb)) { skb->data_len -= skb->len - len; skb->len = len; } else { - if (len <= skb_headlen(skb)) { - skb->len = len; - skb->data_len = 0; - skb->tail = skb->data + len; - if (skb_shinfo(skb)->frag_list && !skb_cloned(skb)) - skb_drop_fraglist(skb); - } else { - skb->data_len -= skb->len - len; - skb->len = len; - } + skb->len = len; + skb->data_len = 0; + skb->tail = skb->data + len; } return 0; |