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Willy Tarreau 8976606ca3 net: linkwatch: fix failure to restore device state across suspend/resume 
[ Upstream commit 6922110d15 ]

After migrating my laptop from 4.19-LTS to 5.4-LTS a while ago I noticed
that my Ethernet port to which a bond and a VLAN interface are attached
appeared to remain up after resuming from suspend with the cable unplugged
(and that problem still persists with 5.10-LTS).

It happens that the following happens:

  - the network driver (e1000e here) prepares to suspend, calls e1000e_down()
    which calls netif_carrier_off() to signal that the link is going down.
  - netif_carrier_off() adds a link_watch event to the list of events for
    this device
  - the device is completely stopped.
  - the machine suspends
  - the cable is unplugged and the machine brought to another location
  - the machine is resumed
  - the queued linkwatch events are processed for the device
  - the device doesn't yet have the __LINK_STATE_PRESENT bit and its events
    are silently dropped
  - the device is resumed with its link down
  - the upper VLAN and bond interfaces are never notified that the link had
    been turned down and remain up
  - the only way to provoke a change is to physically connect the machine
    to a port and possibly unplug it.

The state after resume looks like this:
  $ ip -br li | egrep 'bond|eth'
  bond0            UP             e8:6a:64:64:64:64 <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP>
  eth0             DOWN           e8:6a:64:64:64:64 <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP>
  eth0.2@eth0      UP             e8:6a:64:64:64:64 <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP>

Placing an explicit call to netdev_state_change() either in the suspend
or the resume code in the NIC driver worked around this but the solution
is not satisfying.

The issue in fact really is in link_watch that loses events while it
ought not to. It happens that the test for the device being present was
added by commit 124eee3f69 ("net: linkwatch: add check for netdevice
being present to linkwatch_do_dev") in 4.20 to avoid an access to
devices that are not present.

Instead of dropping events, this patch proceeds slightly differently by
postponing their handling so that they happen after the device is fully
resumed.

Fixes: 124eee3f69 ("net: linkwatch: add check for netdevice being present to linkwatch_do_dev")
Link: https://lists.openwall.net/netdev/2018/03/15/62
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20210809160628.22623-1-w@1wt.eu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2021-08-18 08:59:13 +02:00
arch ARC: fp: set FPU_STATUS.FWE to enable FPU_STATUS update on context switch 2021-08-18 08:59:06 +02:00
block blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() 2021-08-12 13:22:08 +02:00
certs certs: add 'x509_revocation_list' to gitignore 2021-07-20 16:05:35 +02:00
crypto crypto: sm2 - fix a memory leak in sm2 2021-07-14 16:56:06 +02:00
Documentation Documentation: Fix intiramfs script name 2021-07-28 14:35:47 +02:00
drivers net: dsa: sja1105: fix broken backpressure in .port_fdb_dump 2021-08-18 08:59:12 +02:00
fs ceph: reduce contention in ceph_check_delayed_caps() 2021-08-18 08:59:06 +02:00
include net: bridge: fix flags interpretation for extern learn fdb entries 2021-08-18 08:59:13 +02:00
init sched/core: Initialize the idle task with preemption disabled 2021-07-14 16:55:50 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel bpf: Fix integer overflow involving bucket_size 2021-08-18 08:59:10 +02:00
lib net: add kcov handle to skb extensions 2021-07-28 14:35:33 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm memblock: make for_each_mem_range() traverse MEMBLOCK_HOTPLUG regions 2021-07-28 14:35:46 +02:00
net net: linkwatch: fix failure to restore device state across suspend/resume 2021-08-18 08:59:13 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:56:23 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2021-08-12 13:22:12 +02:00
security bpf: Add lockdown check for probe_write_user helper 2021-08-15 14:00:25 +02:00
sound ASoC: cs42l42: Fix LRCLK frame start edge 2021-08-18 08:59:09 +02:00
tools libbpf: Fix probe for BPF_PROG_TYPE_CGROUP_SOCKOPT 2021-08-18 08:59:09 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:22:17 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile Linux 5.10.59 2021-08-15 14:00:27 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.