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sock: allocate skbs from optmem

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Add sock_omalloc and sock_ofree to be able to allocate control skbs,
for instance for looping errors onto sk_error_queue.

The transmit budget (sk_wmem_alloc) is involved in transmit skb
shaping, most notably in TCP Small Queues. Using this budget for
control packets would impact transmission.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2017-08-03 16:29:37 -04:00 committed by David S. Miller
parent 84b7187ca2
commit 98ba0bd550
2 changed files with 29 additions and 0 deletions
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2
include/net/sock.h
View File

@ -1531,6 +1531,8 @@ struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
gfp_t priority);
void __sock_wfree(struct sk_buff *skb);
void sock_wfree(struct sk_buff *skb);
struct sk_buff *sock_omalloc(struct sock *sk, unsigned long size,
gfp_t priority);
void skb_orphan_partial(struct sk_buff *skb);
void sock_rfree(struct sk_buff *skb);
void sock_efree(struct sk_buff *skb);

27
net/core/sock.c
View File

@ -1923,6 +1923,33 @@ struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
}
EXPORT_SYMBOL(sock_wmalloc);
static void sock_ofree(struct sk_buff *skb)
{
struct sock *sk = skb->sk;
atomic_sub(skb->truesize, &sk->sk_omem_alloc);
}
struct sk_buff *sock_omalloc(struct sock *sk, unsigned long size,
gfp_t priority)
{
struct sk_buff *skb;
/* small safe race: SKB_TRUESIZE may differ from final skb->truesize */
if (atomic_read(&sk->sk_omem_alloc) + SKB_TRUESIZE(size) >
sysctl_optmem_max)
return NULL;
skb = alloc_skb(size, priority);
if (!skb)
return NULL;
atomic_add(skb->truesize, &sk->sk_omem_alloc);
skb->sk = sk;
skb->destructor = sock_ofree;
return skb;
}
/*
* Allocate a memory block from the socket's option memory buffer.
*/