[PATCH 5.4 46/70] ipv4: convert fib_num_tclassid_users to atomic_t

Greg Kroah-Hartman
2021-12-06T15:24:06Z

From: Eric Dumazet <edumazet@google.com>

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>
---
include/net/ip_fib.h | 2 +-
include/net/netns/ipv4.h | 2 +-
net/ipv4/fib_frontend.c | 2 +-
net/ipv4/fib_rules.c | 4 ++--
net/ipv4/fib_semantics.c | 4 ++--
5 files changed, 7 insertions(+), 7 deletions(-)

--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -412,7 +412,7 @@ int fib_validate_source(struct sk_buff *
#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)
--- 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;
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1588,7 +1588,7 @@ static int __net_init fib_net_init(struc
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)
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -258,7 +258,7 @@ static int fib4_rule_configure(struct fi
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

@@ -290,7 +290,7 @@ static int fib4_rule_delete(struct fib_r

#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;

--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -222,7 +222,7 @@ void fib_nh_release(struct net *net, str
{
#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);
}
@@ -624,7 +624,7 @@ int fib_nh_init(struct net *net, struct
#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;