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Date: Wed, 17 Sep 2014 04:49:49 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] net: add alloc_skb_with_frags() helper
From: Eric Dumazet <edumazet@...gle.com>
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@...gle.com>
---
include/linux/skbuff.h | 6 +++
net/core/skbuff.c | 78 +++++++++++++++++++++++++++++++++++++++
net/core/sock.c | 78 +++++++--------------------------------
3 files changed, 99 insertions(+), 63 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 756e3d057e84..f1bfa3781c75 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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)
{
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 29f7f0121491..06a8feb10099 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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);
diff --git a/net/core/sock.c b/net/core/sock.c
index 6f436b5e4961..de887c45c63b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -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;
- }
-
- err = -ENOBUFS;
- gfp_mask = sk->sk_allocation;
- if (gfp_mask & __GFP_WAIT)
- gfp_mask |= __GFP_REPEAT;
+ if (sk_wmem_alloc_get(sk) < sk->sk_sndbuf)
+ break;
- 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;
}
--
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