From 98ba0bd5505dcbb90322a4be07bcfe6b8a18c73f Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Thu, 3 Aug 2017 16:29:37 -0400
Subject: [PATCH] sock: allocate skbs from optmem
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>
---
include/net/sock.h | 2 ++
net/core/sock.c | 27 +++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
diff --git a/include/net/sock.h b/include/net/sock.h
index 393c38e9f6aa79..0f778d3c430066 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -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);
diff --git a/net/core/sock.c b/net/core/sock.c
index 742f68c9c84a2b..1261880bdcc81c 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -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.
*/
--
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