path: root/include/linux/if_macvlan.h
diff options
authorHerbert Xu <herbert@gondor.apana.org.au>2010-07-21 21:44:31 +0000
committerDavid S. Miller <davem@davemloft.net>2010-07-22 13:08:56 -0700
commit8a35747a5d13b99e076b0222729e0caa48cb69b6 (patch)
tree387e2840fe46edd9cc36027cf188778f2c5ab1ff /include/linux/if_macvlan.h
parentbded64a7ff82f6af56426a4ff2483888e5ad5fe9 (diff)
macvtap: Limit packet queue length
Mark Wagner reported OOM symptoms when sending UDP traffic over a macvtap link to a kvm receiver. This appears to be caused by the fact that macvtap packet queues are unlimited in length. This means that if the receiver can't keep up with the rate of flow, then we will hit OOM. Of course it gets worse if the OOM killer then decides to kill the receiver. This patch imposes a cap on the packet queue length, in the same way as the tuntap driver, using the device TX queue length. Please note that macvtap currently has no way of giving congestion notification, that means the software device TX queue cannot be used and packets will always be dropped once the macvtap driver queue fills up. This shouldn't be a great problem for the scenario where macvtap is used to feed a kvm receiver, as the traffic is most likely external in origin so congestion notification can't be applied anyway. Of course, if anybody decides to complain about guest-to-guest UDP packet loss down the track, then we may have to revisit this. Incidentally, this patch also fixes a real memory leak when macvtap_get_queue fails. Chris Wright noticed that for this patch to work, we need a non-zero TX queue length. This patch includes his work to change the default macvtap TX queue length to 500. Reported-by: Mark Wagner <mwagner@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Chris Wright <chrisw@sous-sol.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/if_macvlan.h')
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index 9ea047aca79..1ffaeffeff7 100644
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -67,6 +67,8 @@ static inline void macvlan_count_rx(const struct macvlan_dev *vlan,
+extern void macvlan_common_setup(struct net_device *dev);
extern int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
struct nlattr *tb[], struct nlattr *data[],
int (*receive)(struct sk_buff *skb),