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  1. 27 Jan, 2021 5 commits
    • Jakub Kicinski's avatar
      Merge branch 'net-fec-fix-temporary-rmii-clock-reset-on-link-up' · 2bd29748
      Jakub Kicinski authored 
      Laurent Badel says:

====================
net: fec: Fix temporary RMII clock reset on link up

v2: fixed a compilation warning

The FEC drivers performs a "hardware reset" of the MAC module when the
link is reported to be up. This causes a short glitch in the RMII clock
due to the hardware reset clearing the receive control register which
controls the MII mode. It seems that some link partners do not tolerate
this glitch, and invalidate the link, which leads to a never-ending loop
of negotiation-link up-link down events.

This was observed with the iMX28 Soc and LAN8720/LAN8742 PHYs, with two
Intel adapters I218-LM and X722-DA2 as link partners, though a number of
other link partners do not seem to mind the clock glitch. Changing the
hardware reset to a software reset (clearing bit 1 of the ECR register)
cured the issue.

Attempts to optimize fec_restart() in order to minimize the duration of
the glitch were unsuccessful. Furthermore manually producing the glitch by
setting MII mode and then back to RMII in two consecutive instructions,
resulting in a clock glitch <10us in duration, was enough to cause the
partner to invalidate the link. This strongly suggests that the root cause
of the link being dropped is indeed the change in clock frequency.

In an effort to minimize changes to driver, the patch proposes to use
soft reset only for tested SoCs (iMX28) and only if the link is up. This
preserves hardware reset in other situations, which might be required for
proper setup of the MAC.
====================

Link: https://lore.kernel.org/r/20210125100745.5090-1-laurentbadel@eaton.comSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      2bd29748
    • Laurent Badel's avatar
      net: fec: Fix temporary RMII clock reset on link up · c730ab42
      Laurent Badel authored 
      fec_restart() does a hard reset of the MAC module when the link status
changes to up. This temporarily resets the R_CNTRL register which controls
the MII mode of the ENET_OUT clock. In the case of RMII, the clock
frequency momentarily drops from 50MHz to 25MHz until the register is
reconfigured. Some link partners do not tolerate this glitch and
invalidate the link causing failure to establish a stable link when using
PHY polling mode. Since as per IEEE802.3 the criteria for link validity
are PHY-specific, what the partner should tolerate cannot be assumed, so
avoid resetting the MII clock by using software reset instead of hardware
reset when the link is up. This is generally relevant only if the SoC
provides the clock to an external PHY and the PHY is configured for RMII.
Signed-off-by: default avatarLaurent Badel <laurentbadel@eaton.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      c730ab42
    • Xie He's avatar
      net: lapb: Add locking to the lapb module · b491e6a7
      Xie He authored 
      In the lapb module, the timers may run concurrently with other code in
this module, and there is currently no locking to prevent the code from
racing on "struct lapb_cb". This patch adds locking to prevent racing.

1. Add "spinlock_t lock" to "struct lapb_cb"; Add "spin_lock_bh" and
"spin_unlock_bh" to APIs, timer functions and notifier functions.

2. Add "bool t1timer_stop, t2timer_stop" to "struct lapb_cb" to make us
able to ask running timers to abort; Modify "lapb_stop_t1timer" and
"lapb_stop_t2timer" to make them able to abort running timers;
Modify "lapb_t2timer_expiry" and "lapb_t1timer_expiry" to make them
abort after they are stopped by "lapb_stop_t1timer", "lapb_stop_t2timer",
and "lapb_start_t1timer", "lapb_start_t2timer".

3. Let lapb_unregister wait for other API functions and running timers
to stop.

4. The lapb_device_event function calls lapb_disconnect_request. In
order to avoid trying to hold the lock twice, add a new function named
"__lapb_disconnect_request" which assumes the lock is held, and make
it called by lapb_disconnect_request and lapb_device_event.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: Martin Schiller <ms@dev.tdt.de>
Signed-off-by: default avatarXie He <xie.he.0141@gmail.com>
Link: https://lore.kernel.org/r/20210126040939.69995-1-xie.he.0141@gmail.comSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      b491e6a7
    • Ivan Vecera's avatar
      team: protect features update by RCU to avoid deadlock · f0947d0d
      Ivan Vecera authored 
      Function __team_compute_features() is protected by team->lock
mutex when it is called from team_compute_features() used when
features of an underlying device is changed. This causes
a deadlock when NETDEV_FEAT_CHANGE notifier for underlying device
is fired due to change propagated from team driver (e.g. MTU
change). It's because callbacks like team_change_mtu() or
team_vlan_rx_{add,del}_vid() protect their port list traversal
by team->lock mutex.

Example (r8169 case where this driver disables TSO for certain MTU
values):
...
[ 6391.348202]  __mutex_lock.isra.6+0x2d0/0x4a0
[ 6391.358602]  team_device_event+0x9d/0x160 [team]
[ 6391.363756]  notifier_call_chain+0x47/0x70
[ 6391.368329]  netdev_update_features+0x56/0x60
[ 6391.373207]  rtl8169_change_mtu+0x14/0x50 [r8169]
[ 6391.378457]  dev_set_mtu_ext+0xe1/0x1d0
[ 6391.387022]  dev_set_mtu+0x52/0x90
[ 6391.390820]  team_change_mtu+0x64/0xf0 [team]
[ 6391.395683]  dev_set_mtu_ext+0xe1/0x1d0
[ 6391.399963]  do_setlink+0x231/0xf50
...

In fact team_compute_features() called from team_device_event()
does not need to be protected by team->lock mutex and rcu_read_lock()
is sufficient there for port list traversal.

Fixes: 3d249d4c ("net: introduce ethernet teaming device")
Cc: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: default avatarIvan Vecera <ivecera@redhat.com>
Reviewed-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20210125074416.4056484-1-ivecera@redhat.comSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      f0947d0d
    • Jakub Kicinski's avatar
      MAINTAINERS: add David Ahern to IPv4/IPv6 maintainers · 5cfeb562
      Jakub Kicinski authored 
      David has been the de-facto maintainer for much of the IP code
for the last couple of years, let's make it official.

Link: https://lore.kernel.org/r/20210122173220.3579491-1-kuba@kernel.orgSigned-off-by: default avatarJakub Kicinski <kuba@kernel.org>
      5cfeb562
  3. 26 Jan, 2021 6 commits
  5. 25 Jan, 2021 21 commits
  7. 24 Jan, 2021 2 commits
  9. 23 Jan, 2021 6 commits
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