net/mlx5e: Verify dev is present in get devlink port ndo

When changing eswitch mode, the netdev is detached from the
hardware resources. So verify dev is present in get devlink
port ndo. Otherwise, we will hit the following panic:

[241535.973539] RIP: 0010:__devlink_port_phys_port_name_get+0x13/0x1b0
[241535.976471] RSP: 0018:ffff9eaf0ae1b7c8 EFLAGS: 00010292
[241535.977471] RAX: 000000000002d370 RBX: 000000000002d370 RCX: 0000000000000000
[241535.978479] RDX: 0000000000000010 RSI: ffff9eaf0ae1b858 RDI: 000000000002d370
[241535.979482] RBP: ffff9eaf0ae1b7e0 R08: 000000000000002a R09: ffff8888d54d13da
[241535.980486] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8888e6700000
[241535.981491] R13: ffff9eaf0ae1b858 R14: 0000000000000010 R15: 0000000000000000
[241535.982489] FS:  00007fd374ef3740(0000) GS:ffff88909ea00000(0000) knlGS:0000000000000000
[241535.983494] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[241535.984487] CR2: 000000000002d444 CR3: 000000089fd26006 CR4: 00000000003706e0
[241535.985502] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[241535.986499] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[241535.987477] Call Trace:
[241535.988426]  ? nla_put_64bit+0x71/0xa0
[241535.989368]  devlink_compat_phys_port_name_get+0x50/0xa0
[241535.990312]  dev_get_phys_port_name+0x4b/0x60
[241535.991252]  rtnl_fill_ifinfo+0x57b/0xcb0
[241535.992192]  rtnl_dump_ifinfo+0x58f/0x6d0
[241535.993123]  ? ksize+0x14/0x20
[241535.994033]  ? __alloc_skb+0xe8/0x250
[241535.994935]  netlink_dump+0x17c/0x300
[241535.995821]  netlink_recvmsg+0x1de/0x2c0
[241535.996677]  sock_recvmsg+0x70/0x80
[241535.997518]  ____sys_recvmsg+0x9b/0x1b0
[241535.998360]  ? iovec_from_user+0x82/0x120
[241535.999202]  ? __import_iovec+0x2c/0x130
[241536.000031]  ___sys_recvmsg+0x94/0x130
[241536.000850]  ? __handle_mm_fault+0x56d/0x6e0
[241536.001668]  __sys_recvmsg+0x5f/0xb0
[241536.002464]  ? syscall_enter_from_user_mode+0x2b/0x80
[241536.003242]  __x64_sys_recvmsg+0x1f/0x30
[241536.004008]  do_syscall_64+0x38/0x50
[241536.004767]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[241536.005532] RIP: 0033:0x7fd375014f47

Fixes: 2ff349c5 ("net/mlx5e: Verify dev is present in some ndos")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Chris Mi <cmi@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/devlink.c

@@ -64,6 +64,8 @@ struct devlink_port *mlx5e_get_devlink_port(struct net_device *dev)
 	struct mlx5e_priv *priv = netdev_priv(dev);
 	struct devlink_port *port;
 
+	if (!netif_device_present(dev))
+		return NULL;
 	port = mlx5e_devlink_get_dl_port(priv);
 	if (port->registered)
 		return port;