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Commit fa17806c authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv4: do not abuse GFP_ATOMIC in inet_netconf_notify_devconf() 



inet_forward_change() runs with RTNL held.
We are allowed to sleep if required.

If we use __in_dev_get_rtnl() instead of __in_dev_get_rcu(),
we no longer have to use GFP_ATOMIC allocations in
inet_netconf_notify_devconf(), meaning we are less likely to miss
notifications under memory pressure, and wont touch precious memory
reserves either and risk dropping incoming packets.

inet_netconf_get_devconf() can also use GFP_KERNEL allocation.

Fixes: edc9e748 ("rtnl/ipv4: use netconf msg to advertise forwarding status")
Fixes: 9e551110 ("rtnl/ipv4: add support of RTM_GETNETCONF")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: default avatarNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent db9a1ba5

net/ipv4/devinet.c

+6 −6
Original line number Diff line number Diff line
@@ -1834,7 +1834,7 @@ void inet_netconf_notify_devconf(struct net *net, int type, int ifindex, 
	struct sk_buff *skb;

	int err = -ENOBUFS;



	skb = nlmsg_new(inet_netconf_msgsize_devconf(type), GFP_ATOMIC);

	skb = nlmsg_new(inet_netconf_msgsize_devconf(type), GFP_KERNEL);

	if (!skb)

		goto errout;
@@ -1846,7 +1846,7 @@ void inet_netconf_notify_devconf(struct net *net, int type, int ifindex, 
		kfree_skb(skb);

		goto errout;

	}

	rtnl_notify(skb, net, 0, RTNLGRP_IPV4_NETCONF, NULL, GFP_ATOMIC);

	rtnl_notify(skb, net, 0, RTNLGRP_IPV4_NETCONF, NULL, GFP_KERNEL);

	return;

errout:

	if (err < 0)
@@ -1903,7 +1903,7 @@ static int inet_netconf_get_devconf(struct sk_buff *in_skb, 
	}



	err = -ENOBUFS;

	skb = nlmsg_new(inet_netconf_msgsize_devconf(NETCONFA_ALL), GFP_ATOMIC);

	skb = nlmsg_new(inet_netconf_msgsize_devconf(NETCONFA_ALL), GFP_KERNEL);

	if (!skb)

		goto errout;
@@ -2027,16 +2027,16 @@ static void inet_forward_change(struct net *net) 


	for_each_netdev(net, dev) {

		struct in_device *in_dev;



		if (on)

			dev_disable_lro(dev);

		rcu_read_lock();

		in_dev = __in_dev_get_rcu(dev);



		in_dev = __in_dev_get_rtnl(dev);

		if (in_dev) {

			IN_DEV_CONF_SET(in_dev, FORWARDING, on);

			inet_netconf_notify_devconf(net, NETCONFA_FORWARDING,

						    dev->ifindex, &in_dev->cnf);

		}

		rcu_read_unlock();

	}

}