ipv4: convert fib_num_tclassid_users to atomic_t

commit 213f5f8f31f10aa1e83187ae20fb7fa4e626b724 upstream.

Before commit faa041a40b9f ("ipv4: Create cleanup helper for fib_nh")
changes to net->ipv4.fib_num_tclassid_users were protected by RTNL.

After the change, this is no longer the case, as free_fib_info_rcu()
runs after rcu grace period, without rtnl being held.

Fixes: faa041a40b9f ("ipv4: Create cleanup helper for fib_nh")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Ahern <dsahern@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 4d431d7..088f257 100644 (file)
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -437,7 +437,7 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 #ifdef CONFIG_IP_ROUTE_CLASSID
 static inline int fib_num_tclassid_users(struct net *net)
 {
-       return net->ipv4.fib_num_tclassid_users;
+       return atomic_read(&net->ipv4.fib_num_tclassid_users);
 }
 #else
 static inline int fib_num_tclassid_users(struct net *net)

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 8e4fcac..75484f4 100644 (file)
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -61,7 +61,7 @@ struct netns_ipv4 {
 #endif
        bool                    fib_has_custom_local_routes;
 #ifdef CONFIG_IP_ROUTE_CLASSID
-       int                     fib_num_tclassid_users;
+       atomic_t                fib_num_tclassid_users;
 #endif
        struct hlist_head       *fib_table_hash;
        bool                    fib_offload_disabled;

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 647bcea..917ea95 100644 (file)
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1578,7 +1578,7 @@ static int __net_init fib_net_init(struct net *net)
        int error;
 
 #ifdef CONFIG_IP_ROUTE_CLASSID
-       net->ipv4.fib_num_tclassid_users = 0;
+       atomic_set(&net->ipv4.fib_num_tclassid_users, 0);
 #endif
        error = ip_fib_net_init(net);
        if (error < 0)

diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 364ad34..d279cb8 100644 (file)
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -264,7 +264,7 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
        if (tb[FRA_FLOW]) {
                rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
                if (rule4->tclassid)
-                       net->ipv4.fib_num_tclassid_users++;
+                       atomic_inc(&net->ipv4.fib_num_tclassid_users);
        }
 #endif
 
@@ -296,7 +296,7 @@ static int fib4_rule_delete(struct fib_rule *rule)
 
 #ifdef CONFIG_IP_ROUTE_CLASSID
        if (((struct fib4_rule *)rule)->tclassid)
-               net->ipv4.fib_num_tclassid_users--;
+               atomic_dec(&net->ipv4.fib_num_tclassid_users);
 #endif
        net->ipv4.fib_has_custom_rules = true;
 

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 642503e..36f3497 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -222,7 +222,7 @@ void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
 {
 #ifdef CONFIG_IP_ROUTE_CLASSID
        if (fib_nh->nh_tclassid)
-               net->ipv4.fib_num_tclassid_users--;
+               atomic_dec(&net->ipv4.fib_num_tclassid_users);
 #endif
        fib_nh_common_release(&fib_nh->nh_common);
 }
@@ -633,7 +633,7 @@ int fib_nh_init(struct net *net, struct fib_nh *nh,
 #ifdef CONFIG_IP_ROUTE_CLASSID
        nh->nh_tclassid = cfg->fc_flow;
        if (nh->nh_tclassid)
-               net->ipv4.fib_num_tclassid_users++;
+               atomic_inc(&net->ipv4.fib_num_tclassid_users);
 #endif
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
        nh->fib_nh_weight = nh_weight;