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Subject[Patch] net: kill an RCU warning in inet_fill_link_af()
Date
From: WANG Cong <amwang@redhat.com>

The latest net-next-2.6 triggers an RCU warning during boot,
lockdep complains that in inet_fill_link_af() we call rcu_dereference_check()
without rcu_read_lock() protection.

This patch fixes it by replacing __in_dev_get_rcu() with in_dev_get().

Signed-off-by: WANG Cong <amwang@redhat.com>

---
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index d9f71ba..73baed8 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1258,31 +1258,36 @@ errout:

static size_t inet_get_link_af_size(const struct net_device *dev)
{
- struct in_device *in_dev = __in_dev_get_rcu(dev);
+ struct in_device *in_dev = in_dev_get(dev);

if (!in_dev)
return 0;

+ in_dev_put(in_dev);
return nla_total_size(IPV4_DEVCONF_MAX * 4); /* IFLA_INET_CONF */
}

static int inet_fill_link_af(struct sk_buff *skb, const struct net_device *dev)
{
- struct in_device *in_dev = __in_dev_get_rcu(dev);
+ struct in_device *in_dev = in_dev_get(dev);
struct nlattr *nla;
- int i;
+ int i, ret = 0;

if (!in_dev)
return -ENODATA;

nla = nla_reserve(skb, IFLA_INET_CONF, IPV4_DEVCONF_MAX * 4);
- if (nla == NULL)
- return -EMSGSIZE;
+ if (nla == NULL) {
+ ret = -EMSGSIZE;
+ goto out;
+ }

for (i = 0; i < IPV4_DEVCONF_MAX; i++)
((u32 *) nla_data(nla))[i] = in_dev->cnf.data[i];

- return 0;
+out:
+ in_dev_put(in_dev);
+ return ret;
}

static const struct nla_policy inet_af_policy[IFLA_INET_MAX+1] = {
@@ -1293,11 +1298,14 @@ static int inet_validate_link_af(const struct net_device *dev,
const struct nlattr *nla)
{
struct nlattr *a, *tb[IFLA_INET_MAX+1];
+ struct in_device *in_dev = in_dev_get(dev);
int err, rem;

- if (dev && !__in_dev_get_rcu(dev))
+ if (dev && !in_dev)
return -EAFNOSUPPORT;

+ in_dev_put(in_dev);
+
err = nla_parse_nested(tb, IFLA_INET_MAX, nla, inet_af_policy);
if (err < 0)
return err;
@@ -1319,7 +1327,7 @@ static int inet_validate_link_af(const struct net_device *dev,

static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla)
{
- struct in_device *in_dev = __in_dev_get_rcu(dev);
+ struct in_device *in_dev = in_dev_get(dev);
struct nlattr *a, *tb[IFLA_INET_MAX+1];
int rem;

@@ -1334,6 +1342,7 @@ static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla)
ipv4_devconf_set(in_dev, nla_type(a), nla_get_u32(a));
}

+ in_dev_put(in_dev);
return 0;
}


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