[PATCH net 3/4] net-sysfs: check device is present when showing testing

[Jamie Bainbridge]

A sysfs reader can race with a device reset or removal.

This was fixed for speed_show with commit 4224cfd7fb65 ("net-sysfs: add
check for netdevice being present to speed_show") so add the same check
to testing_show.

Fixes: db30a57779b1 ("net: Add testing sysfs attribute")

Signed-off-by: Jamie Bainbridge <jamie.bainbridge@xxxxxxxxx>
---
 net/core/net-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 3a539a2bd4d11c5f5d7b6f15a23d61439f178c3b..17927832a4fbb56d3e1dfbed29c567d70ab944be 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -291,7 +291,7 @@ static ssize_t testing_show(struct device *dev,
 {
 	struct net_device *netdev = to_net_dev(dev);
 
-	if (netif_running(netdev))
+	if (netif_running(netdev) && netif_device_present(netdev))
 		return sysfs_emit(buf, fmt_dec, !!netif_testing(netdev));
 
 	return -EINVAL;
-- 
2.39.2