[PATCH 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro

From: Amol Grover
Date: Sat Feb 22 2020 - 01:42:20 EST


ipmr_for_each_table() uses list_for_each_entry_rcu() for
traversing outside of an RCU read-side critical section but
under the protection of pernet_ops_rwsem. Hence add the
corresponding lockdep expression to silence the following
false-positive warning at boot:

[ 0.645292] =============================
[ 0.645294] WARNING: suspicious RCU usage
[ 0.645296] 5.5.4-stable #17 Not tainted
[ 0.645297] -----------------------------
[ 0.645299] net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!

Signed-off-by: Amol Grover <frextrite@xxxxxxxxx>
---
net/ipv4/ipmr.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 99c864eb6e34..950ffe9943da 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
static void ipmr_expire_process(struct timer_list *t);

#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
- lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net) \
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held() || \
+ lockdep_is_held(&pernet_ops_rwsem))

static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1