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net: add alloc_skb_with_frags() helper 

Extract from sock_alloc_send_pskb() code building skb with frags,
so that we can reuse this in other contexts.

Intent is to use it from tcp_send_rcvq(), tcp_collapse(), ...

We also want to replace some skb_linearize() calls to a more reliable
strategy in pathological cases where we need to reduce number of frags.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-09-17 04:49:49 -07:00 committed by David S. Miller
parent cb93471acc
commit 2e4e441071
3 changed files with 99 additions and 63 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/skbuff.h
View File

@ -769,6 +769,12 @@ static inline struct sk_buff *alloc_skb(unsigned int size,
return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
}
struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
unsigned long data_len,
int max_page_order,
int *errcode,
gfp_t gfp_mask);
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
gfp_t priority)
{

78
net/core/skbuff.c
View File

@ -4102,3 +4102,81 @@ err_free:
return NULL;
}
EXPORT_SYMBOL(skb_vlan_untag);
/**
* alloc_skb_with_frags - allocate skb with page frags
*
* header_len: size of linear part
* data_len: needed length in frags
* max_page_order: max page order desired.
* errcode: pointer to error code if any
* gfp_mask: allocation mask
*
* This can be used to allocate a paged skb, given a maximal order for frags.
*/
struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
unsigned long data_len,
int max_page_order,
int *errcode,
gfp_t gfp_mask)
{
int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
unsigned long chunk;
struct sk_buff *skb;
struct page *page;
gfp_t gfp_head;
int i;
*errcode = -EMSGSIZE;
/* Note this test could be relaxed, if we succeed to allocate
* high order pages...
*/
if (npages > MAX_SKB_FRAGS)
return NULL;
gfp_head = gfp_mask;
if (gfp_head & __GFP_WAIT)
gfp_head |= __GFP_REPEAT;
*errcode = -ENOBUFS;
skb = alloc_skb(header_len, gfp_head);
if (!skb)
return NULL;
skb->truesize += npages << PAGE_SHIFT;
for (i = 0; npages > 0; i++) {
int order = max_page_order;
while (order) {
if (npages >= 1 << order) {
page = alloc_pages(gfp_mask |
__GFP_COMP |
__GFP_NOWARN |
__GFP_NORETRY,
order);
if (page)
goto fill_page;
/* Do not retry other high order allocations */
order = 1;
max_page_order = 0;
}
order--;
}
page = alloc_page(gfp_mask);
if (!page)
goto failure;
fill_page:
chunk = min_t(unsigned long, data_len,
PAGE_SIZE << order);
skb_fill_page_desc(skb, i, page, 0, chunk);
data_len -= chunk;
npages -= 1 << order;
}
return skb;
failure:
kfree_skb(skb);
return NULL;
}
EXPORT_SYMBOL(alloc_skb_with_frags);

78
net/core/sock.c
View File

@ -1762,21 +1762,12 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len,
unsigned long data_len, int noblock,
int *errcode, int max_page_order)
{
struct sk_buff *skb = NULL;
unsigned long chunk;
gfp_t gfp_mask;
struct sk_buff *skb;
long timeo;
int err;
int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
struct page *page;
int i;
err = -EMSGSIZE;
if (npages > MAX_SKB_FRAGS)
goto failure;
timeo = sock_sndtimeo(sk, noblock);
while (!skb) {
for (;;) {
err = sock_error(sk);
if (err != 0)
goto failure;
@ -1785,66 +1776,27 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len,
if (sk->sk_shutdown & SEND_SHUTDOWN)
goto failure;
if (atomic_read(&sk->sk_wmem_alloc) >= sk->sk_sndbuf) {
set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
err = -EAGAIN;
if (!timeo)
goto failure;
if (signal_pending(current))
goto interrupted;
timeo = sock_wait_for_wmem(sk, timeo);
continue;
}
if (sk_wmem_alloc_get(sk) < sk->sk_sndbuf)
break;
err = -ENOBUFS;
gfp_mask = sk->sk_allocation;
if (gfp_mask & __GFP_WAIT)
gfp_mask |= __GFP_REPEAT;
skb = alloc_skb(header_len, gfp_mask);
if (!skb)
set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
err = -EAGAIN;
if (!timeo)
goto failure;
skb->truesize += data_len;
for (i = 0; npages > 0; i++) {
int order = max_page_order;
while (order) {
if (npages >= 1 << order) {
page = alloc_pages(sk->sk_allocation |
__GFP_COMP |
__GFP_NOWARN |
__GFP_NORETRY,
order);
if (page)
goto fill_page;
/* Do not retry other high order allocations */
order = 1;
max_page_order = 0;
}
order--;
}
page = alloc_page(sk->sk_allocation);
if (!page)
goto failure;
fill_page:
chunk = min_t(unsigned long, data_len,
PAGE_SIZE << order);
skb_fill_page_desc(skb, i, page, 0, chunk);
data_len -= chunk;
npages -= 1 << order;
}
if (signal_pending(current))
goto interrupted;
timeo = sock_wait_for_wmem(sk, timeo);
}
skb_set_owner_w(skb, sk);
skb = alloc_skb_with_frags(header_len, data_len, max_page_order,
errcode, sk->sk_allocation);
if (skb)
skb_set_owner_w(skb, sk);
return skb;
interrupted:
err = sock_intr_errno(timeo);
failure:
kfree_skb(skb);
*errcode = err;
return NULL;
}