linux-stable.git/net/core/link_watch.c, branch linux-5.4.y

net: linkwatch: use system_unbound_wq

2024-08-19T03:33:46+00:00

[ Upstream commit 3e7917c0cdad835a5121520fc5686d954b7a61ab ]

linkwatch_event() grabs possibly very contended RTNL mutex.

system_wq is not suitable for such work.

Inspired by many noisy syzbot reports.

3 locks held by kworker/0:7/5266:
 #0: ffff888015480948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3206 [inline]
 #0: ffff888015480948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3312
 #1: ffffc90003f6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3207 [inline]
 , at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3312
 #2: ffffffff8fa6f208 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:276

Reported-by: syzbot 
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20240805085821.1616528-1-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: linkwatch: fix failure to restore device state across suspend/resume

2021-08-18T06:57:00+00:00

[ Upstream commit 6922110d152e56d7569616b45a1f02876cf3eb9f ]

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 
  eth0             DOWN           e8:6a:64:64:64:64 
  eth0.2@eth0      UP             e8:6a:64:64:64:64 

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 124eee3f6955 ("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: 124eee3f6955 ("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 
Cc: Geert Uytterhoeven 
Cc: Florian Fainelli 
Signed-off-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20210809160628.22623-1-w@1wt.eu
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: link_watch: prevent starvation when processing linkwatch wq

2019-07-02T02:02:47+00:00

When user has configured a large number of virtual netdev, such
as 4K vlans, the carrier on/off operation of the real netdev
will also cause it's virtual netdev's link state to be processed
in linkwatch. Currently, the processing is done in a work queue,
which may cause rtnl locking starvation problem and worker
starvation problem for other work queue, such as irqfd_inject wq.

This patch releases the cpu when link watch worker has processed
a fixed number of netdev' link watch event, and schedule the
work queue again when there is still link watch event remaining.

Signed-off-by: Yunsheng Lin 
Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

net: linkwatch: add check for netdevice being present to linkwatch_do_dev

2018-09-20T04:06:46+00:00

When bringing down the netdevice (incl. detaching it) and calling
netif_carrier_off directly or indirectly the latter triggers an
asynchronous linkwatch event.
This linkwatch event eventually may fail to access chip registers in
the ndo_get_stats/ndo_get_stats64 callback because the device isn't
accessible any longer, see call trace in [0].

To prevent this scenario don't check for IFF_UP only, but also make
sure that the netdevice is present.

[0] https://lists.openwall.net/netdev/2018/03/15/62

Signed-off-by: Heiner Kallweit 
Tested-by: Geert Uytterhoeven 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net: link_watch: mark bonding link events urgent

2018-01-24T00:43:30+00:00

It takes 1sec for bond link down notification to hit user-space
when all slaves of the bond go down. 1sec is too long for
protocol daemons in user-space relying on bond notification
to recover (eg: multichassis lag implementations in user-space).
Since the link event code already marks team device port link events
 as urgent, this patch moves the code to cover all lag ports and master.

Signed-off-by: Roopa Prabhu 
Acked-by: Jiri Pirko 
Reviewed-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

dev: introduce dev_get_iflink()

2015-04-02T18:04:59+00:00

The goal of this patch is to prepare the removal of the iflink field. It
introduces a new ndo function, which will be implemented by virtual interfaces.

There is no functional change into this patch. All readers of iflink field
now call dev_get_iflink().

Signed-off-by: Nicolas Dichtel 
Signed-off-by: David S. Miller

net/core: include linux/types.h instead of asm/types.h

2014-11-18T20:26:32+00:00

Signed-off-by: Fabian Frederick 
Signed-off-by: David S. Miller

arch: Mass conversion of smp_mb__*()

2014-04-18T12:20:48+00:00

Mostly scripted conversion of the smp_mb__* barriers.

Signed-off-by: Peter Zijlstra 
Acked-by: Paul E. McKenney 
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds 
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar

net: make all team port device link events urgent

2013-06-13T09:31:41+00:00

Since team functionality relies heavily on userspace daemon, we need to
deliver event to userspace via Netlink as quick as possible. So make all
team port device link events urgent.

Signed-off-by: Flavio Leitner 
Signed-off-by: Jiri Pirko 
Signed-off-by: David S. Miller