Commit 9cc9a5cb authored by Tonghao Zhang's avatar Tonghao Zhang Committed by David S. Miller
Browse files

datapath: Avoid using stack larger than 1024. 



When compiling OvS-master on 4.4.0-81 kernel,
there is a warning:

    CC [M]  /root/ovs/datapath/linux/datapath.o
    /root/ovs/datapath/linux/datapath.c: In function
    'ovs_flow_cmd_set':
    /root/ovs/datapath/linux/datapath.c:1221:1: warning:
    the frame size of 1040 bytes is larger than 1024 bytes
    [-Wframe-larger-than=]

This patch factors out match-init and action-copy to avoid
"Wframe-larger-than=1024" warning. Because mask is only
used to get actions, we new a function to save some
stack space.

Signed-off-by: default avatarTonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: default avatarPravin B Shelar <pshelar@ovn.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7e5988df

net/openvswitch/datapath.c

+58 −23
Original line number Diff line number Diff line
@@ -1090,6 +1090,58 @@ static struct sw_flow_actions *get_flow_actions(struct net *net, 
	return acts;

}



/* Factor out match-init and action-copy to avoid

 * "Wframe-larger-than=1024" warning. Because mask is only

 * used to get actions, we new a function to save some

 * stack space.

 *

 * If there are not key and action attrs, we return 0

 * directly. In the case, the caller will also not use the

 * match as before. If there is action attr, we try to get

 * actions and save them to *acts. Before returning from

 * the function, we reset the match->mask pointer. Because

 * we should not to return match object with dangling reference

 * to mask.

 * */

static int ovs_nla_init_match_and_action(struct net *net,

					 struct sw_flow_match *match,

					 struct sw_flow_key *key,

					 struct nlattr **a,

					 struct sw_flow_actions **acts,

					 bool log)

{

	struct sw_flow_mask mask;

	int error = 0;



	if (a[OVS_FLOW_ATTR_KEY]) {

		ovs_match_init(match, key, true, &mask);

		error = ovs_nla_get_match(net, match, a[OVS_FLOW_ATTR_KEY],

					  a[OVS_FLOW_ATTR_MASK], log);

		if (error)

			goto error;

	}



	if (a[OVS_FLOW_ATTR_ACTIONS]) {

		if (!a[OVS_FLOW_ATTR_KEY]) {

			OVS_NLERR(log,

				  "Flow key attribute not present in set flow.");

			return -EINVAL;

		}



		*acts = get_flow_actions(net, a[OVS_FLOW_ATTR_ACTIONS], key,

					 &mask, log);

		if (IS_ERR(*acts)) {

			error = PTR_ERR(*acts);

			goto error;

		}

	}



	/* On success, error is 0. */

error:

	match->mask = NULL;

	return error;

}



static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info)

{

	struct net *net = sock_net(skb->sk);
@@ -1097,7 +1149,6 @@ static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info) 
	struct ovs_header *ovs_header = info->userhdr;

	struct sw_flow_key key;

	struct sw_flow *flow;

	struct sw_flow_mask mask;

	struct sk_buff *reply = NULL;

	struct datapath *dp;

	struct sw_flow_actions *old_acts = NULL, *acts = NULL;
@@ -1109,34 +1160,18 @@ static int ovs_flow_cmd_set(struct sk_buff *skb, struct genl_info *info) 
	bool ufid_present;



	ufid_present = ovs_nla_get_ufid(&sfid, a[OVS_FLOW_ATTR_UFID], log);

	if (a[OVS_FLOW_ATTR_KEY]) {

		ovs_match_init(&match, &key, true, &mask);

		error = ovs_nla_get_match(net, &match, a[OVS_FLOW_ATTR_KEY],

					  a[OVS_FLOW_ATTR_MASK], log);

	} else if (!ufid_present) {

	if (!a[OVS_FLOW_ATTR_KEY] && !ufid_present) {

		OVS_NLERR(log,

			  "Flow set message rejected, Key attribute missing.");

		error = -EINVAL;

	}

	if (error)

		goto error;



	/* Validate actions. */

	if (a[OVS_FLOW_ATTR_ACTIONS]) {

		if (!a[OVS_FLOW_ATTR_KEY]) {

			OVS_NLERR(log,

				  "Flow key attribute not present in set flow.");

			error = -EINVAL;

			goto error;

		return -EINVAL;

	}



		acts = get_flow_actions(net, a[OVS_FLOW_ATTR_ACTIONS], &key,

					&mask, log);

		if (IS_ERR(acts)) {

			error = PTR_ERR(acts);

	error = ovs_nla_init_match_and_action(net, &match, &key, a,

					      &acts, log);

	if (error)

		goto error;

		}



	if (acts) {

		/* Can allocate before locking if have acts. */

		reply = ovs_flow_cmd_alloc_info(acts, &sfid, info, false,

						ufid_flags);

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