From: Haiyang Zhang <haiya...@microsoft.com>
The loop in default_device_exit_net() won't be able to properly detect the
head then stop, and will hit NULL pointer, when a driver, like hv_netvsc,
automatically moves the slave device together with the master device.
To fix this, add a helper function to return the first migratable netdev
correctly, no matter one or two devices were removed from this net's list
in the last iteration.
Cc: sta...@vger.kernel.org # 5.4+
Signed-off-by: Haiyang Zhang <haiya...@microsoft.com>
---
net/core/dev.c | 31 +++++++++++++++++++++----------
1 file changed, 21 insertions(+), 10 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 621a639aeba1..d83f5f12cf70 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -12629,19 +12629,11 @@ static struct pernet_operations __net_initdata
netdev_net_ops = {
.exit = netdev_exit,
};
-static void __net_exit default_device_exit_net(struct net *net)
+static inline struct net_device *first_migratable_netdev(struct net *net)
{
- struct netdev_name_node *name_node, *tmp;
struct net_device *dev, *aux;
- /*
- * Push all migratable network devices back to the
- * initial network namespace
- */
- ASSERT_RTNL();
- for_each_netdev_safe(net, dev, aux) {
- int err;
- char fb_name[IFNAMSIZ];
+ for_each_netdev_safe(net, dev, aux) {
/* Ignore unmoveable devices (i.e. loopback) */
if (dev->netns_immutable)
continue;
@@ -12650,6 +12642,25 @@ static void __net_exit default_device_exit_net(struct
net *net)
if (dev->rtnl_link_ops && !dev->rtnl_link_ops->netns_refund)
continue;
+ return dev;
+ }
+
+ return NULL;
+}
+
+static void __net_exit default_device_exit_net(struct net *net)
+{
+ struct netdev_name_node *name_node, *tmp;
+ struct net_device *dev;
+ /*
+ * Push all migratable network devices back to the
+ * initial network namespace
+ */
+ ASSERT_RTNL();
+ while ((dev = first_migratable_netdev(net)) != NULL) {
+ int err;
+ char fb_name[IFNAMSIZ];
+
/* Push remaining network devices to init_net */
snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
if (netdev_name_in_use(&init_net, fb_name))
--
2.34.1
