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ipv4: use READ_ONCE()/WRITE_ONCE() on net->ipv4.fib_seq

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Using RTNL to protect ops->fib_rules_seq reads seems a big hammer.

Writes are protected by RTNL.
We can use READ_ONCE() when reading it.

Constify 'struct net' argument of fib4_rules_seq_read()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241009184405.3752829-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-10-09 18:44:02 +00:00 committed by Jakub Kicinski
parent a716ff52be
commit 16207384d2
4 changed files with 8 additions and 8 deletions
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4
include/net/ip_fib.h
View File

@ -347,7 +347,7 @@ static inline int fib4_rules_dump(struct net *net, struct notifier_block *nb,
return 0;
}
static inline unsigned int fib4_rules_seq_read(struct net *net)
static inline unsigned int fib4_rules_seq_read(const struct net *net)
{
return 0;
}
@ -411,7 +411,7 @@ static inline bool fib4_has_custom_rules(const struct net *net)
bool fib4_rule_default(const struct fib_rule *rule);
int fib4_rules_dump(struct net *net, struct notifier_block *nb,
struct netlink_ext_ack *extack);
unsigned int fib4_rules_seq_read(struct net *net);
unsigned int fib4_rules_seq_read(const struct net *net);
static inline bool fib4_rules_early_flow_dissect(struct net *net,
struct sk_buff *skb,

2
include/net/netns/ipv4.h
View File

@ -262,7 +262,7 @@ struct netns_ipv4 {
#endif
struct fib_notifier_ops *notifier_ops;
unsigned int fib_seq; /* protected by rtnl_mutex */
unsigned int fib_seq; /* writes protected by rtnl_mutex */
struct fib_notifier_ops *ipmr_notifier_ops;
unsigned int ipmr_seq; /* protected by rtnl_mutex */

8
net/ipv4/fib_notifier.c
View File

@ -22,15 +22,15 @@ int call_fib4_notifiers(struct net *net, enum fib_event_type event_type,
ASSERT_RTNL();
info->family = AF_INET;
net->ipv4.fib_seq++;
/* Paired with READ_ONCE() in fib4_seq_read() */
WRITE_ONCE(net->ipv4.fib_seq, net->ipv4.fib_seq + 1);
return call_fib_notifiers(net, event_type, info);
}
static unsigned int fib4_seq_read(struct net *net)
{
ASSERT_RTNL();
return net->ipv4.fib_seq + fib4_rules_seq_read(net);
/* Paired with WRITE_ONCE() in call_fib4_notifiers() */
return READ_ONCE(net->ipv4.fib_seq) + fib4_rules_seq_read(net);
}
static int fib4_dump(struct net *net, struct notifier_block *nb,

2
net/ipv4/fib_rules.c
View File

@ -74,7 +74,7 @@ int fib4_rules_dump(struct net *net, struct notifier_block *nb,
return fib_rules_dump(net, nb, AF_INET, extack);
}
unsigned int fib4_rules_seq_read(struct net *net)
unsigned int fib4_rules_seq_read(const struct net *net)
{
return fib_rules_seq_read(net, AF_INET);
}