static int
__new_pgfrag(struct sk_buff *skb, struct sk_buff *pskb, int size, int i,
int shift)
{
int off = 0;
struct page *page = NULL;
skb_frag_t *frag;
BUG_ON(i > MAX_SKB_FRAGS);
frag = __lookup_pgfrag_room(skb, size);
if (frag) {
page = skb_frag_page(frag);
off = ss_skb_frag_len(frag);
__skb_frag_ref(frag);
} else {
page = alloc_page(GFP_ATOMIC);
if (!page)
return -ENOMEM;
}
if (__extend_pgfrags(skb, pskb, i, shift)) {
if (!frag)
__free_page(page);
return -ENOMEM;
}
if (i == MAX_SKB_FRAGS) {
/*
* Insert a new paged fragment right after the last one
* in @skb, i.e. as the first fragment of the next skb.
*/
skb = skb_shinfo(pskb ? : skb)->frag_list;
i = 0;
}
/*
* Make room for @shift fragments starting with slot @i. Then make
* a new fragment in slot @i that can hold @size bytes, and it set up.
*/
static int
__new_pgfrag(struct sk_buff *skb, int size, int i, int shift, TfwStr *it)
{
int off = 0;
struct page *page = NULL;
skb_frag_t *frag;
BUG_ON(i > MAX_SKB_FRAGS);
/*
* Try to find room for @size bytes in SKB fragments.
* If none found, then allocate a new page for the fragment.
*/
frag = __lookup_pgfrag_room(skb, size);
if (frag) {
page = skb_frag_page(frag);
off = ss_skb_frag_len(frag);
__skb_frag_ref(frag); /* get_page(page); */
} else {
page = alloc_page(GFP_ATOMIC);
if (!page)
return -ENOMEM;
}
/* Make room for @shift fragments starting with slot @i. */
if (__extend_pgfrags(skb, i, shift, it)) {
if (frag)
__skb_frag_unref(frag); /* put_page(page); */
else
__free_page(page);
return -ENOMEM;
}
/*
* When the requested slot is right outside the range of the
* array of paged fragments, then the new fragment is put as
* the first fragment of the next SKB.
*/
if (i == MAX_SKB_FRAGS) {
i = 0;
skb = it->skb;
}
/* Set up the new fragment in slot @i to hold @size bytes. */
__skb_fill_page_desc(skb, i, page, off, size);
ss_skb_adjust_data_len(skb, size);
return 0;
}
/**
* Somewhat like skb_shift().
*
* Beware: @from can be equal to MAX_SKB_FRAGS if we need to insert a new
* fragment after the last one.
*/
static int
__extend_pgfrags(struct sk_buff *skb, struct sk_buff *pskb, int from, int n)
{
int i, n_frag = 0;
struct skb_shared_info *psi, *si = skb_shinfo(skb);
if (skb_shinfo(skb)->nr_frags > MAX_SKB_FRAGS - n) {
skb_frag_t *f;
struct sk_buff *skb_frag;
psi = pskb ? skb_shinfo(pskb) : si;
skb_frag = psi->frag_list;
n_frag = skb_shinfo(skb)->nr_frags + n - MAX_SKB_FRAGS;
if (skb_frag && !skb_headlen(skb_frag)
&& skb_shinfo(skb_frag)->nr_frags <= MAX_SKB_FRAGS - n_frag)
{
int r = __extend_pgfrags(skb_frag, NULL, 0, n_frag);
if (r)
return r;
} else {
skb_frag = alloc_skb(0, GFP_ATOMIC);
if (!skb_frag)
return -ENOMEM;
skb_frag->next = psi->frag_list;
psi->frag_list = skb_frag;
}
for (i = n_frag - 1;
i >= 0 && MAX_SKB_FRAGS - n + i >= from; --i)
{
f = &si->frags[MAX_SKB_FRAGS - n + i];
skb_shinfo(skb_frag)->frags[i] = *f;
ss_skb_adjust_data_len(skb, -skb_frag_size(f));
ss_skb_adjust_data_len(skb_frag, skb_frag_size(f));
}
skb_shinfo(skb_frag)->nr_frags += n_frag;
skb->ip_summed = CHECKSUM_PARTIAL;
skb_frag->ip_summed = CHECKSUM_PARTIAL;
}
memmove(&si->frags[from + n], &si->frags[from],
(si->nr_frags - from - n_frag) * sizeof(skb_frag_t));
si->nr_frags += n - n_frag;
return 0;
}
/**
* Delete @len (the value is positive now) bytes from @frag.
*
* @return 0 on success, -errno on failure.
* @return SKB in @it->skb if new SKB is allocated.
* @return pointer to data after the deleted area in @it->ptr.
* @return @it->flags is set if @it->ptr points to data in it->skb.
*/
static int
__split_pgfrag_del(struct sk_buff *skb, int i, int off, int len, TfwStr *it)
{
int tail_len;
struct sk_buff *skb_dst;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
struct skb_shared_info *si = skb_shinfo(skb);
SS_DBG("[%d]: %s: skb [%p] i [%d] off [%d] len [%d] fragsize [%d]\n",
smp_processor_id(), __func__,
skb, i, off, len, skb_frag_size(frag));
if (unlikely(off + len > skb_frag_size(frag))) {
SS_WARN("Attempt to delete too much\n");
return -EFAULT;
}
/* Fast path: delete a full fragment. */
if (!off && len == skb_frag_size(frag)) {
ss_skb_adjust_data_len(skb, -len);
__skb_frag_unref(frag);
if (i + 1 < si->nr_frags)
memmove(&si->frags[i], &si->frags[i + 1],
(si->nr_frags - i - 1) * sizeof(skb_frag_t));
--si->nr_frags;
goto lookup_next_ptr;
}
/* Fast path: delete the head part of a fragment. */
if (!off) {
frag->page_offset += len;
skb_frag_size_sub(frag, len);
ss_skb_adjust_data_len(skb, -len);
it->ptr = skb_frag_address(frag);
return 0;
}
/* Fast path: delete the tail part of a fragment. */
if (off + len == skb_frag_size(frag)) {
skb_frag_size_sub(frag, len);
ss_skb_adjust_data_len(skb, -len);
++i;
goto lookup_next_ptr;
}
/*
* Delete data in the middle of a fragment. After the data
* is deleted the fragment will contain only the head part,
* and the tail part is moved to another fragment.
* [frag @i] [frag @i+1 - tail data]
*
* Make room for a fragment right after the @i fragment
* to move the tail part of data there.
*/
if (__extend_pgfrags(skb, i + 1, 1, it))
return -EFAULT;
/* Find the SKB for tail data. */
skb_dst = (i < MAX_SKB_FRAGS - 1) ? skb : it->skb;
/* Calculate the length of the tail part. */
tail_len = skb_frag_size(frag) - off - len;
/* Trim the fragment with the head part. */
skb_frag_size_sub(frag, len + tail_len);
/* Make the fragment with the tail part. */
i = (i + 1) % MAX_SKB_FRAGS;
__skb_fill_page_desc(skb_dst, i, skb_frag_page(frag),
frag->page_offset + off + len, tail_len);
__skb_frag_ref(frag);
/* Adjust SKB data lengths. */
ss_skb_adjust_data_len(skb, -len);
if (skb != skb_dst) {
ss_skb_adjust_data_len(skb, -tail_len);
ss_skb_adjust_data_len(skb_dst, tail_len);
}
/* Get the SKB and the address of data after the deleted area. */
it->flags = (skb != skb_dst);
it->ptr = skb_frag_address(&skb_shinfo(skb_dst)->frags[i]);
return 0;
lookup_next_ptr:
/* Get the next fragment after the deleted fragment. */
if (i < si->nr_frags)
it->ptr = skb_frag_address(&si->frags[i]);
return 0;
}
/**
* The kernel may allocate a bit more memory for an SKB than what was
* requested (see ksize() call in __alloc_skb()). Use the extra memory
* if it's enough to hold @n bytes. Otherwise, allocate new linear data.
*
* @return 0 on success, -errno on failure.
* @return SKB in @it->skb if new SKB is allocated.
* @return pointer to the room for new data in @it->ptr if making room.
* @return pointer to data right after the deleted fragment in @it->ptr.
*/
static int
__split_linear_data(struct sk_buff *skb, char *pspt, int len, TfwStr *it)
{
int alloc = len > 0;
int tail_len = (char *)skb_tail_pointer(skb) - pspt;
struct page *page = virt_to_head_page(skb->head);
SS_DBG("[%d]: %s: skb [%p] pspt [%p] len [%d] tail_len [%d]\n",
smp_processor_id(), __func__, skb, pspt, len, tail_len);
BUG_ON(!skb->head_frag);
BUG_ON(tail_len <= 0);
BUG_ON(!(alloc | tail_len));
BUG_ON(-len > tail_len);
/*
* Quick and unlikely path: just advance the skb tail pointer.
* Note that this only works when we make room. When we remove,
* pspt points at the start of the data chunk to remove. In that
* case, tail_len can never be zero.
*/
if (unlikely(!tail_len && len <= ss_skb_tailroom(skb))) {
BUG_ON(len < 0);
it->ptr = ss_skb_put(skb, len);
return 0;
}
/*
* Quick and unlikely path: just move skb tail pointer backward.
* Note that this only works when we remove data, and the data
* is located exactly at the end of the linear part of an skb.
*/
if (unlikely((len < 0) && (tail_len == -len))) {
ss_skb_put(skb, len);
if (skb_is_nonlinear(skb))
it->ptr = skb_frag_address(&skb_shinfo(skb)->frags[0]);
return 0;
}
/*
* Data is inserted or deleted in the middle of the linear part,
* or there's insufficient room in the linear part of an SKB to
* insert @len bytes.
*
* Don't bother with skb tail room: if the linear part is large,
* then it's likely that we'll do some smaller data insertions
* later and go by the quick path above. Otherwise, the tail size
* is also small.
*
* The inserted data is placed in a fragment. The tail part is
* moved to yet another fragment. The linear part is trimmed to
* exclude the deleted data and the tail part.
*
* Do all allocations before moving the fragments to avoid complex
* rollback.
*/
if (alloc) {
if (__new_pgfrag(skb, len, 0, alloc + !!tail_len, it))
return -EFAULT;
} else {
if (__extend_pgfrags(skb, 0, 1, it))
return -EFAULT;
tail_len += len; /* @len is negative. */
}
if (tail_len) {
int tail_off = pspt - (char *)page_address(page);
/*
* Trim the linear part by |@len| bytes if data
* is deleted. Then trim it further to exclude
* the tail data. Finally, set up the fragment
* allotted above with the tail data.
*/
if (len < 0) {
tail_off -= len;
skb->tail += len;
skb->len += len;
}
skb->tail -= tail_len;
skb->data_len += tail_len;
skb->truesize += tail_len;
__skb_fill_page_desc(skb, alloc, page, tail_off, tail_len);
skb_frag_ref(skb, alloc); /* get_page(page); */
}
it->ptr = skb_frag_address(&skb_shinfo(skb)->frags[0]);
return 0;
}
