Subject: [PATCH AUTOSEL 4.14 02/27] hv_netvsc: Fix a warning of suspicious RCU usage

From: Sasha Levin <[email-masked]>
Date: Thu, 29 Aug 2019 14:16:28 -0400

From: Dexuan Cui <[email-masked]>

[ Upstream commit 6d0d779dca73cd5acb649c54f81401f93098b298 ]

This fixes a warning of "suspicious rcu_dereference_check() usage"
when nload runs.

Fixes: 776e726bfb34 ("netvsc: fix RCU warning in get_stats")
Signed-off-by: Dexuan Cui <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 drivers/net/hyperv/netvsc_drv.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index eb92720dd1c4a..33c1f6548fb79 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -1170,12 +1170,15 @@ static void netvsc_get_stats64(struct net_device *net,
 			       struct rtnl_link_stats64 *t)
 {
 	struct net_device_context *ndev_ctx = netdev_priv(net);
-	struct netvsc_device *nvdev = rcu_dereference_rtnl(ndev_ctx->nvdev);
+	struct netvsc_device *nvdev;
 	struct netvsc_vf_pcpu_stats vf_tot;
 	int i;
 
+	rcu_read_lock();
+
+	nvdev = rcu_dereference(ndev_ctx->nvdev);
 	if (!nvdev)
-		return;
+		goto out;
 
 	netdev_stats_to_stats64(t, &net->stats);
 
@@ -1214,6 +1217,8 @@ static void netvsc_get_stats64(struct net_device *net,
 		t->rx_packets	+= packets;
 		t->multicast	+= multicast;
 	}
+out:
+	rcu_read_unlock();
 }
 
 static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
-- 
2.20.1