net: netdevsim: use xso.real_dev instead of xso.dev in callback functions of struct xfrmdev_ops

There are two pointers in struct xfrm_state_offload, *dev, *real_dev.
These are used in callback functions of struct xfrmdev_ops.
The *dev points whether bonding interface or real interface.
If bonding ipsec offload is used, it points bonding interface If not,
it points real interface.
And real_dev always points real interface.
So, netdevsim should always use real_dev instead of dev.
Of course, real_dev always not be null.

Test commands:
ip netns add A
ip netns exec A bash
modprobe netdevsim
echo "1 1" > /sys/bus/netdevsim/new_device
ip link add bond0 type bond mode active-backup
ip link set eth0 master bond0
ip link set eth0 up
ip link set bond0 up
ip x s add proto esp dst 14.1.1.1 src 15.1.1.1 spi 0x07 mode \
transport reqid 0x07 replay-window 32 aead 'rfc4106(gcm(aes))' \
0x44434241343332312423222114131211f4f3f2f1 128 sel src 14.0.0.52/24 \
dst 14.0.0.70/24 proto tcp offload dev bond0 dir in

Splat looks like:
BUG: spinlock bad magic on CPU#5, kworker/5:1/53
lock: 0xffff8881068c2cc8, .magic: 11121314, .owner: <none>/-1,
.owner_cpu: -235736076
CPU: 5 PID: 53 Comm: kworker/5:1 Not tainted 5.13.0-rc3+ #1168
Workqueue: events linkwatch_event
Call Trace:
dump_stack+0xa4/0xe5
do_raw_spin_lock+0x20b/0x270
? rwlock_bug.part.1+0x90/0x90
_raw_spin_lock_nested+0x5f/0x70
bond_get_stats+0xe4/0x4c0 [bonding]
? rcu_read_lock_sched_held+0xc0/0xc0
? bond_neigh_init+0x2c0/0x2c0 [bonding]
? dev_get_alias+0xe2/0x190
? dev_get_port_parent_id+0x14a/0x360
? rtnl_unregister+0x190/0x190
? dev_get_phys_port_name+0xa0/0xa0
? memset+0x1f/0x40
? memcpy+0x38/0x60
? rtnl_phys_switch_id_fill+0x91/0x100
dev_get_stats+0x8c/0x270
rtnl_fill_stats+0x44/0xbe0
? nla_put+0xbe/0x140
rtnl_fill_ifinfo+0x1054/0x3ad0
[ ... ]

Fixes: 272c2330adc9 ("xfrm: bail early on slave pass over skb")
Signed-off-by: Taehee Yoo <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/netdevsim/ipsec.c

···
 				       u32 *mykey, u32 *mysalt)
 {
 	const char aes_gcm_name[] = "rfc4106(gcm(aes))";
-	struct net_device *dev = xs->xso.dev;
+	struct net_device *dev = xs->xso.real_dev;
 	unsigned char *key_data;
 	char *alg_name = NULL;
 	int key_len;
···
 	u16 sa_idx;
 	int ret;
 
-	dev = xs->xso.dev;
+	dev = xs->xso.real_dev;
 	ns = netdev_priv(dev);
 	ipsec = &ns->ipsec;
 
···
 
 static void nsim_ipsec_del_sa(struct xfrm_state *xs)
 {
-	struct netdevsim *ns = netdev_priv(xs->xso.dev);
+	struct netdevsim *ns = netdev_priv(xs->xso.real_dev);
 	struct nsim_ipsec *ipsec = &ns->ipsec;
 	u16 sa_idx;
 
···
 
 static bool nsim_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs)
 {
-	struct netdevsim *ns = netdev_priv(xs->xso.dev);
+	struct netdevsim *ns = netdev_priv(xs->xso.real_dev);
 	struct nsim_ipsec *ipsec = &ns->ipsec;
 
 	ipsec->ok++;