From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: No address after suspend/resume with 4.18
Date: Fri, 30 Nov 2018 15:26:15 -0800
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Cc: netdev@vger.kernel.org
To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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On my box with Debian testing, I see a new problem with suspend/resume of wired network device.
Using stock Debian kernel 4.18.0-2-amd64

After suspend/resume cycle, IP address is lost.

Device Info:
$ /sbin/ethtool -i enp12s0
driver: igb
version: 5.4.0-k
firmware-version:  0. 6-1
expansion-rom-version: 
bus-info: 0000:0c:00.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: yes


$ lspci -v -s 0000:0c:00.0
0c:00.0 Ethernet controller: Intel Corporation I211 Gigabit Network Connection (rev 03)
	Subsystem: Gigabyte Technology Co., Ltd I211 Gigabit Network Connection
	Flags: bus master, fast devsel, latency 0, IRQ 17, NUMA node 0
	Memory at dfb00000 (32-bit, non-prefetchable) [size=128K]
	I/O ports at c000 [size=32]
	Memory at dfb20000 (32-bit, non-prefetchable) [size=16K]
	Capabilities: <access denied>
	Kernel driver in use: igb
	Kernel modules: igb

State before suspend:
$ ip addr show dev enp12s0
4: enp12s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 1c:1b:0d:0a:4b:0e brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.18/24 brd 192.168.1.255 scope global enp12s0
       valid_lft forever preferred_lft forever

State after resume:

$ ip addr show dev enp12s0
4: enp12s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 1c:1b:0d:0a:4b:0e brd ff:ff:ff:ff:ff:f

Doing ifdown/ifup which restarts the DHCP client does restore the address.

Not sure if this is a kernel issue with carrier handling, Intel driver issue, or DHCP client issue.