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    Subject[PATCH 2/5] AF_RXRPC: Move generic skbuff stuff from XFRM code to generic code [try #3]
    Date
    Move generic skbuff stuff from XFRM code to generic code so that AF_RXRPC can
    use it too.

    The kdoc comments I've attached to the functions needs to be checked by whoever
    wrote them as I had to make some guesses about the workings of these functions.

    Signed-Off-By: David Howells <dhowells@redhat.com>
    ---

    include/linux/skbuff.h | 6 ++
    include/net/esp.h | 2 -
    net/core/skbuff.c | 188 ++++++++++++++++++++++++++++++++++++++++++++++++
    net/xfrm/xfrm_algo.c | 169 -------------------------------------------
    4 files changed, 194 insertions(+), 171 deletions(-)

    diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
    index 4ff3940..9e70270 100644
    --- a/include/linux/skbuff.h
    +++ b/include/linux/skbuff.h
    @@ -83,6 +83,7 @@
    */

    struct net_device;
    +struct scatterlist;

    #ifdef CONFIG_NETFILTER
    struct nf_conntrack {
    @@ -363,6 +364,11 @@ extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
    extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
    int newheadroom, int newtailroom,
    gfp_t priority);
    +extern int skb_to_sgvec(struct sk_buff *skb,
    + struct scatterlist *sg, int offset,
    + int len);
    +extern int skb_cow_data(struct sk_buff *skb, int tailbits,
    + struct sk_buff **trailer);
    extern int skb_pad(struct sk_buff *skb, int pad);
    #define dev_kfree_skb(a) kfree_skb(a)
    extern void skb_over_panic(struct sk_buff *skb, int len,
    diff --git a/include/net/esp.h b/include/net/esp.h
    index 713d039..d05d8d2 100644
    --- a/include/net/esp.h
    +++ b/include/net/esp.h
    @@ -40,8 +40,6 @@ struct esp_data
    } auth;
    };

    -extern int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len);
    -extern int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
    extern void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);

    static inline int esp_mac_digest(struct esp_data *esp, struct sk_buff *skb,
    diff --git a/net/core/skbuff.c b/net/core/skbuff.c
    index 702fa8f..f3ed31b 100644
    --- a/net/core/skbuff.c
    +++ b/net/core/skbuff.c
    @@ -55,6 +55,7 @@
    #include <linux/cache.h>
    #include <linux/rtnetlink.h>
    #include <linux/init.h>
    +#include <linux/scatterlist.h>

    #include <net/protocol.h>
    #include <net/dst.h>
    @@ -2060,6 +2061,190 @@ void __init skb_init(void)
    NULL, NULL);
    }

    +/**
    + * skb_to_sgvec - Fill a scatter-gather list from a socket buffer
    + * @skb: Socket buffer containing the buffers to be mapped
    + * @sg: The scatter-gather list to map into
    + * @offset: The offset into the buffer's contents to start mapping
    + * @len: Length of buffer space to be mapped
    + *
    + * Fill the specified scatter-gather list with mappings/pointers into a
    + * region of the buffer space attached to a socket buffer.
    + */
    +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 elt = 0;
    +
    + if (copy > 0) {
    + if (copy > len)
    + copy = len;
    + sg[elt].page = virt_to_page(skb->data + offset);
    + sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
    + sg[elt].length = copy;
    + elt++;
    + if ((len -= copy) == 0)
    + return elt;
    + offset += copy;
    + }
    +
    + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
    + int end;
    +
    + BUG_TRAP(start <= offset + len);
    +
    + end = start + 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].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);
    +
    + end = start + list->len;
    + if ((copy = end - offset) > 0) {
    + if (copy > len)
    + copy = len;
    + elt += skb_to_sgvec(list, sg+elt, offset - start, copy);
    + if ((len -= copy) == 0)
    + return elt;
    + offset += copy;
    + }
    + start = end;
    + }
    + }
    + BUG_ON(len);
    + return elt;
    +}
    +
    +/**
    + * skb_cow_data - Check that a socket buffer's data buffers are writable
    + * @skb: The socket buffer to check.
    + * @tailbits: Amount of trailing space to be added
    + * @trailer: Returned pointer to the skb where the @tailbits space begins
    + *
    + * Make sure that the data buffers attached to a socket buffer are
    + * writable. If they are not, private copies are made of the data buffers
    + * and the socket buffer is set to use these instead.
    + *
    + * If @tailbits is given, make sure that there is space to write @tailbits
    + * bytes of data beyond current end of socket buffer. @trailer will be
    + * set to point to the skb in which this space begins.
    + *
    + * The number of scatterlist elements required to completely map the
    + * COW'd and extended socket buffer will be returned.
    + */
    +int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
    +{
    + int copyflag;
    + int elt;
    + struct sk_buff *skb1, **skb_p;
    +
    + /* If skb is cloned or its head is paged, reallocate
    + * head pulling out all the pages (pages are considered not writable
    + * at the moment even if they are anonymous).
    + */
    + if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
    + __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
    + return -ENOMEM;
    +
    + /* Easy case. Most of packets will go this way. */
    + if (!skb_shinfo(skb)->frag_list) {
    + /* A little of trouble, not enough of space for trailer.
    + * This should not happen, when stack is tuned to generate
    + * good frames. OK, on miss we reallocate and reserve even more
    + * space, 128 bytes is fair. */
    +
    + if (skb_tailroom(skb) < tailbits &&
    + pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
    + return -ENOMEM;
    +
    + /* Voila! */
    + *trailer = skb;
    + return 1;
    + }
    +
    + /* Misery. We are in troubles, going to mincer fragments... */
    +
    + elt = 1;
    + skb_p = &skb_shinfo(skb)->frag_list;
    + copyflag = 0;
    +
    + while ((skb1 = *skb_p) != NULL) {
    + int ntail = 0;
    +
    + /* The fragment is partially pulled by someone,
    + * this can happen on input. Copy it and everything
    + * after it. */
    +
    + if (skb_shared(skb1))
    + copyflag = 1;
    +
    + /* If the skb is the last, worry about trailer. */
    +
    + if (skb1->next == NULL && tailbits) {
    + if (skb_shinfo(skb1)->nr_frags ||
    + skb_shinfo(skb1)->frag_list ||
    + skb_tailroom(skb1) < tailbits)
    + ntail = tailbits + 128;
    + }
    +
    + if (copyflag ||
    + skb_cloned(skb1) ||
    + ntail ||
    + skb_shinfo(skb1)->nr_frags ||
    + skb_shinfo(skb1)->frag_list) {
    + struct sk_buff *skb2;
    +
    + /* Fuck, we are miserable poor guys... */
    + if (ntail == 0)
    + skb2 = skb_copy(skb1, GFP_ATOMIC);
    + else
    + skb2 = skb_copy_expand(skb1,
    + skb_headroom(skb1),
    + ntail,
    + GFP_ATOMIC);
    + if (unlikely(skb2 == NULL))
    + return -ENOMEM;
    +
    + if (skb1->sk)
    + skb_set_owner_w(skb2, skb1->sk);
    +
    + /* Looking around. Are we still alive?
    + * OK, link new skb, drop old one */
    +
    + skb2->next = skb1->next;
    + *skb_p = skb2;
    + kfree_skb(skb1);
    + skb1 = skb2;
    + }
    + elt++;
    + *trailer = skb1;
    + skb_p = &skb1->next;
    + }
    +
    + return elt;
    +}
    +
    EXPORT_SYMBOL(___pskb_trim);
    EXPORT_SYMBOL(__kfree_skb);
    EXPORT_SYMBOL(kfree_skb);
    @@ -2094,3 +2279,6 @@ EXPORT_SYMBOL(skb_seq_read);
    EXPORT_SYMBOL(skb_abort_seq_read);
    EXPORT_SYMBOL(skb_find_text);
    EXPORT_SYMBOL(skb_append_datato_frags);
    +
    +EXPORT_SYMBOL_GPL(skb_to_sgvec);
    +EXPORT_SYMBOL_GPL(skb_cow_data);
    diff --git a/net/xfrm/xfrm_algo.c b/net/xfrm/xfrm_algo.c
    index f373a8a..6249a94 100644
    --- a/net/xfrm/xfrm_algo.c
    +++ b/net/xfrm/xfrm_algo.c
    @@ -612,175 +612,6 @@ EXPORT_SYMBOL_GPL(skb_icv_walk);

    #if defined(CONFIG_INET_ESP) || defined(CONFIG_INET_ESP_MODULE) || defined(CONFIG_INET6_ESP) || defined(CONFIG_INET6_ESP_MODULE)

    -/* Looking generic it is not used in another places. */
    -
    -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 elt = 0;
    -
    - if (copy > 0) {
    - if (copy > len)
    - copy = len;
    - sg[elt].page = virt_to_page(skb->data + offset);
    - sg[elt].offset = (unsigned long)(skb->data + offset) % PAGE_SIZE;
    - sg[elt].length = copy;
    - elt++;
    - if ((len -= copy) == 0)
    - return elt;
    - offset += copy;
    - }
    -
    - for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
    - int end;
    -
    - BUG_TRAP(start <= offset + len);
    -
    - end = start + 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].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);
    -
    - end = start + list->len;
    - if ((copy = end - offset) > 0) {
    - if (copy > len)
    - copy = len;
    - elt += skb_to_sgvec(list, sg+elt, offset - start, copy);
    - if ((len -= copy) == 0)
    - return elt;
    - offset += copy;
    - }
    - start = end;
    - }
    - }
    - BUG_ON(len);
    - return elt;
    -}
    -EXPORT_SYMBOL_GPL(skb_to_sgvec);
    -
    -/* Check that skb data bits are writable. If they are not, copy data
    - * to newly created private area. If "tailbits" is given, make sure that
    - * tailbits bytes beyond current end of skb are writable.
    - *
    - * Returns amount of elements of scatterlist to load for subsequent
    - * transformations and pointer to writable trailer skb.
    - */
    -
    -int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
    -{
    - int copyflag;
    - int elt;
    - struct sk_buff *skb1, **skb_p;
    -
    - /* If skb is cloned or its head is paged, reallocate
    - * head pulling out all the pages (pages are considered not writable
    - * at the moment even if they are anonymous).
    - */
    - if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
    - __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
    - return -ENOMEM;
    -
    - /* Easy case. Most of packets will go this way. */
    - if (!skb_shinfo(skb)->frag_list) {
    - /* A little of trouble, not enough of space for trailer.
    - * This should not happen, when stack is tuned to generate
    - * good frames. OK, on miss we reallocate and reserve even more
    - * space, 128 bytes is fair. */
    -
    - if (skb_tailroom(skb) < tailbits &&
    - pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
    - return -ENOMEM;
    -
    - /* Voila! */
    - *trailer = skb;
    - return 1;
    - }
    -
    - /* Misery. We are in troubles, going to mincer fragments... */
    -
    - elt = 1;
    - skb_p = &skb_shinfo(skb)->frag_list;
    - copyflag = 0;
    -
    - while ((skb1 = *skb_p) != NULL) {
    - int ntail = 0;
    -
    - /* The fragment is partially pulled by someone,
    - * this can happen on input. Copy it and everything
    - * after it. */
    -
    - if (skb_shared(skb1))
    - copyflag = 1;
    -
    - /* If the skb is the last, worry about trailer. */
    -
    - if (skb1->next == NULL && tailbits) {
    - if (skb_shinfo(skb1)->nr_frags ||
    - skb_shinfo(skb1)->frag_list ||
    - skb_tailroom(skb1) < tailbits)
    - ntail = tailbits + 128;
    - }
    -
    - if (copyflag ||
    - skb_cloned(skb1) ||
    - ntail ||
    - skb_shinfo(skb1)->nr_frags ||
    - skb_shinfo(skb1)->frag_list) {
    - struct sk_buff *skb2;
    -
    - /* Fuck, we are miserable poor guys... */
    - if (ntail == 0)
    - skb2 = skb_copy(skb1, GFP_ATOMIC);
    - else
    - skb2 = skb_copy_expand(skb1,
    - skb_headroom(skb1),
    - ntail,
    - GFP_ATOMIC);
    - if (unlikely(skb2 == NULL))
    - return -ENOMEM;
    -
    - if (skb1->sk)
    - skb_set_owner_w(skb2, skb1->sk);
    -
    - /* Looking around. Are we still alive?
    - * OK, link new skb, drop old one */
    -
    - skb2->next = skb1->next;
    - *skb_p = skb2;
    - kfree_skb(skb1);
    - skb1 = skb2;
    - }
    - elt++;
    - *trailer = skb1;
    - skb_p = &skb1->next;
    - }
    -
    - return elt;
    -}
    -EXPORT_SYMBOL_GPL(skb_cow_data);
    -
    void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
    {
    if (tail != skb) {
    -
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      Last update: 2007-03-20 21:27    [W:0.042 / U:3.524 seconds]
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