[PATCH v1 net 2/2] net: fib_rules: Don't dump dying fib_rule in fib_rules_dump().

[Kuniyuki Iwashima <kuniyu@google.com>]

rocker_router_fib_event() calls fib_rule_get() during RCU dump.

If the fib_rule is dying, refcount_inc() will complain about it.

Let's call refcount_inc_not_zero() in fib_rules_dump().

Fixes: 5d7bfd141924 ("ipv4: fib_rules: Dump FIB rules when registering FIB notifier")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 include/net/fib_rules.h | 5 +++++
 net/core/fib_rules.c    | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 6e68e359ad18..7dee0ae616e3 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -111,6 +111,11 @@ static inline void fib_rule_get(struct fib_rule *rule)
 	refcount_inc(&rule->refcnt);
 }
 
+static inline bool fib_rule_get_safe(struct fib_rule *rule)
+{
+	return refcount_inc_not_zero(&rule->refcnt);
+}
+
 static inline void fib_rule_put(struct fib_rule *rule)
 {
 	if (refcount_dec_and_test(&rule->refcnt))
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 8ca634964e36..cf374c208732 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -349,7 +349,7 @@ int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 
 		if (err != -EAGAIN) {
 			if ((arg->flags & FIB_LOOKUP_NOREF) ||
-			    likely(refcount_inc_not_zero(&rule->refcnt))) {
+			    likely(fib_rule_get_safe(rule))) {
 				arg->rule = rule;
 				goto out;
 			}
@@ -410,8 +410,12 @@ int fib_rules_dump(struct net *net, struct notifier_block *nb, int family,
 	if (!ops)
 		return -EAFNOSUPPORT;
 	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
+		if (!fib_rule_get_safe(rule))
+			continue;
+
 		err = call_fib_rule_notifier(nb, FIB_EVENT_RULE_ADD,
 					     rule, family, extack);
+		fib_rule_put(rule);
 		if (err)
 			break;
 	}
-- 
2.54.0.1099.g489fc7bff1-goog