diff options
authorThomas Graf <>2013-09-03 13:37:01 +0200
committerGreg Kroah-Hartman <>2013-09-14 06:54:56 -0700
commit4b7ead801d3e174ae14ccaed02773041419ae278 (patch)
parent5612d36ca1438c23280b962a80943d14b2e9f778 (diff)
ipv6: Don't depend on per socket memory for neighbour discovery messages
[ Upstream commit 25a6e6b84fba601eff7c28d30da8ad7cfbef0d43 ] Allocating skbs when sending out neighbour discovery messages currently uses sock_alloc_send_skb() based on a per net namespace socket and thus share a socket wmem buffer space. If a netdevice is temporarily unable to transmit due to carrier loss or for other reasons, the queued up ndisc messages will cosnume all of the wmem space and will thus prevent from any more skbs to be allocated even for netdevices that are able to transmit packets. The number of neighbour discovery messages sent is very limited, use of alloc_skb() bypasses the socket wmem buffer size enforcement while the manual call to skb_set_owner_w() maintains the socket reference needed for the IPv6 output path. This patch has orginally been posted by Eric Dumazet in a modified form. Signed-off-by: Thomas Graf <> Cc: Eric Dumazet <> Cc: Hannes Frederic Sowa <> Cc: Stephen Warren <> Cc: Fabio Estevam <> Tested-by: Fabio Estevam <> Tested-by: Stephen Warren <> Acked-by: Hannes Frederic Sowa <> Signed-off-by: David S. Miller <> Signed-off-by: Greg Kroah-Hartman <>
1 files changed, 8 insertions, 6 deletions
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index ca4ffcc287f1..060a0449acaa 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -372,14 +372,11 @@ static struct sk_buff *ndisc_alloc_skb(struct net_device *dev,
int tlen = dev->needed_tailroom;
struct sock *sk = dev_net(dev)->ipv6.ndisc_sk;
struct sk_buff *skb;
- int err;
- skb = sock_alloc_send_skb(sk,
- hlen + sizeof(struct ipv6hdr) + len + tlen,
- 1, &err);
+ skb = alloc_skb(hlen + sizeof(struct ipv6hdr) + len + tlen, GFP_ATOMIC);
if (!skb) {
- ND_PRINTK(0, err, "ndisc: %s failed to allocate an skb, err=%d\n",
- __func__, err);
+ ND_PRINTK(0, err, "ndisc: %s failed to allocate an skb\n",
+ __func__);
return NULL;
@@ -389,6 +386,11 @@ static struct sk_buff *ndisc_alloc_skb(struct net_device *dev,
skb_reserve(skb, hlen + sizeof(struct ipv6hdr));
+ /* Manually assign socket ownership as we avoid calling
+ * sock_alloc_send_pskb() to bypass wmem buffer limits
+ */
+ skb_set_owner_w(skb, sk);
return skb;