Commit Graph

949550 Commits

Author SHA1 Message Date
Miaohe Lin 34e1ec319e net: ipv4: remove unused arg exact_dif in compute_score
The arg exact_dif is not used anymore, remove it. inet_exact_dif_match()
is no longer needed after the above is removed, so remove it too.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 13:08:29 -07:00
Miaohe Lin 3f7d820bad net: ipv6: remove unused arg exact_dif in compute_score
The arg exact_dif is not used anymore, remove it. inet6_exact_dif_match()
is no longer needed after the above is removed, remove it too.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 13:08:10 -07:00
David S. Miller 10eb466794 Merge branch 'net-phy-add-Lynx-PCS-MDIO-module'
Ioana Ciornei says:

====================
net: phy: add Lynx PCS MDIO module

Add support for the Lynx PCS as a separate module in drivers/net/phy/.
The advantage of this structure is that multiple ethernet or switch
drivers used on NXP hardware (ENETC, Seville, Felix DSA switch etc) can
share the same implementation of PCS configuration and runtime
management.

The module implements phylink_pcs_ops and exports a phylink_pcs
(incorporated into a lynx_pcs) which can be directly passed to phylink
through phylink_pcs_set.

The first 3 patches add some missing pieces in phylink and the locked
mdiobus write accessor. Next, the Lynx PCS MDIO module is added as a
standalone module. The majority of the code is extracted from the Felix
DSA driver. The last patch makes the necessary changes in the Felix and
Seville drivers in order to use the new common PCS implementation.

At the moment, USXGMII (only with in-band AN), SGMII, QSGMII (with and
without in-band AN) and 2500Base-X (only w/o in-band AN) are supported
by the Lynx PCS MDIO module since these were also supported by Felix and
no functional change is intended at this time.

Changes in v2:
 * got rid of the mdio_lynx_pcs structure and directly exported the
 functions without the need of an indirection
 * made the necessary adjustments for this in the Felix DSA driver
 * solved the broken allmodconfig build test by making the module
 tristate instead of bool
 * fixed a memory leakage in the Felix driver (the pcs structure was
 allocated twice)

Changes in v3:
 * added support for PHYLINK PCS ops in DSA (patch 5/9)
 * cleanup in Felix PHYLINK operations and migrate to
 phylink_mac_link_up() being the callback of choice for applying MAC
 configuration (patches 6-8)

Changes in v4:
 * use the newly introduced phylink PCS mechanism
 * install the phylink_pcs in the phylink_mac_config DSA ops
 * remove the direct implementations of the PCS ops
 * do no use the SGMII_ prefix when referring to the IF_MORE register
 * add a phylink helper to decode the USXGMII code word
 * remove cleanup patches for Felix (these have been already accepted)
 * Seville (recently introduced) now has PCS support through the same
 Lynx PCS module

Changes in v5:
 - move the pcs-lynx driver to drivers/net/pcs
 - reword the commit message a bit in 4/5
 - add error checking and error propagation in 4/5
 - s/IF_MODE_DUPLEX/IF_MODE_HALF_DUPLEX in 4/5
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:52:33 -07:00
Ioana Ciornei 588d05504d net: dsa: ocelot: use the Lynx PCS helpers in Felix and Seville
Use the helper functions introduced by the newly added
Lynx PCS MDIO module in the Felix VSC9959 and Seville VSC9953.

Instead of representing the PCS as a phy_device, a mdio_device structure
will be passed to the Lynx module which is now actually implementing all
the PCS configuration and status reporting.

All code previously used for PCS monitoring and runtime configuration
is removed and replaced will calls to the Lynx PCS operations.

Tested on the following SERDES protocols of LS1028A: 0x7777
(2500Base-X), 0x85bb (QSGMII), 0x9999 (SGMII) and 0x13bb (USXGMII).

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:52:33 -07:00
Ioana Ciornei 0da4c3d393 net: phy: add Lynx PCS module
Add a Lynx PCS module which exposes the necessary operations to drive
the PCS using phylink.

The majority of the code is extracted from the Felix DSA driver, which
will be also modified in a later patch, and exposed as a separate module
for code reusability purposes.
As such, this aims at feature and bug parity with the existing Felix DSA
driver, and thus USXGMII, SGMII, QSGMII and 2500Base-X (only w/o in-band
AN) are supported by the Lynx PCS module since these were also supported
by Felix.

The module can only be enabled by the drivers in need and not user
selectable.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:52:33 -07:00
Ioana Ciornei 2dab432c5a net: mdiobus: add clause 45 mdiobus write accessor
Add the locked variant of the clause 45 mdiobus write accessor -
mdiobus_c45_write().

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:52:33 -07:00
Ioana Ciornei 29f02ee477 net: phylink: consider QSGMII interface mode in phylink_mii_c22_pcs_get_state
The same link partner advertisement word is used for both QSGMII and
SGMII, thus treat both interface modes using the same
phylink_decode_sgmii_word() function.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:52:33 -07:00
Ioana Ciornei afd6220999 net: phylink: add helper function to decode USXGMII word
With the new addition of the USXGMII link partner ability constants we
can now introduce a phylink helper that decodes the USXGMII word and
populates the appropriate fields in the phylink_link_state structure
based on them.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:52:33 -07:00
YueHaibing d60432994e net/wan/fsl_ucc_hdlc: Add MODULE_DESCRIPTION
Add missing MODULE_DESCRIPTION.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:41:50 -07:00
YueHaibing 26613a9559 net: hns: Remove unused macro AE_NAME_PORT_ID_IDX
There is no caller in tree.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:41:28 -07:00
YueHaibing 52db4bcafc net: dl2k: Remove unused macro DRV_NAME
There is no caller in tree any more.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:41:06 -07:00
YueHaibing d32575aa62 net: wan: slic_ds26522: Remove unused macro DRV_NAME
There is no caller in tree any more.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:40:42 -07:00
YueHaibing 622a63f6f3 tipc: Remove unused macro TIPC_NACK_INTV
There is no caller in tree any more.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:39:07 -07:00
YueHaibing ff007a9ba2 tipc: Remove unused macro TIPC_FWD_MSG
There is no caller in tree any more.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:38:48 -07:00
YueHaibing b1fd4470cd mptcp: Remove unused macro MPTCP_SAME_STATE
There is no caller in tree any more.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:37:40 -07:00
Miaohe Lin 5af68891dc net: clean up codestyle
This is a pure codestyle cleanup patch. No functional change intended.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:33:34 -07:00
Miaohe Lin cbc08a3312 net: Use helper macro IP_MAX_MTU in __ip_append_data()
What 0xFFFF means here is actually the max mtu of a ip packet. Use help
macro IP_MAX_MTU here.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:33:16 -07:00
Grygorii Strashko 4d4dce31ef net: ethernet: ti: am65-cpts: fix i2083 genf (and estf) Reconfiguration Issue
The new bit TX_GENF_CLR_EN has been added in AM65x SR2.0 to fix i2083
errata, which can be just set unconditionally for all SoCs.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:29:52 -07:00
David S. Miller 31b143e5b7 Merge branch 'sfc-clean-up-some-W-1-build-warnings'
Edward Cree says:

====================
sfc: clean up some W=1 build warnings

A collection of minor fixes to issues flagged up by W=1.
After this series, the only remaining warnings in the sfc driver are
 some 'member missing in kerneldoc' warnings from ptp.c.
Tested by building on x86_64 and running 'ethtool -p' on an EF10 NIC;
 there was no error, but I couldn't observe the actual LED as I'm
 working remotely.

[ Incidentally, ethtool_phys_id()'s behaviour on an error return
  looks strange — if I'm reading it right, it will break out of the
  inner loop but not the outer one, and eventually return the rc
  from the last run of the inner loop.  Is this intended? ]
====================

Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:28:50 -07:00
Edward Cree f2ed621fad sfc: return errors from efx_mcdi_set_id_led, and de-indirect
W=1 warnings indicated that 'rc' was unused in efx_mcdi_set_id_led();
 change the function to return int instead of void and plumb the rc
 through the caller efx_ethtool_phys_id().
Since (post-Falcon) all sfc NICs use MCDI for this, there's no point in
 indirecting through a nic_type method, so remove that and just call
 efx_mcdi_set_id_led() directly.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:28:50 -07:00
Edward Cree b1d11fdbe5 sfc: fix kernel-doc on struct efx_loopback_state
Missing 'struct' keyword caused "cannot understand function prototype"
 warnings.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:28:50 -07:00
Edward Cree b6d96931ca sfc: fix unused-but-set-variable warning in efx_farch_filter_remove_safe
Thanks to some past refactor, 'spec' is not actually used in this
 function; the code using it moved to the callee efx_farch_filter_remove.
Remove the variable to fix a W=1 warning.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:28:50 -07:00
Edward Cree 35ff765f8d sfc: fix W=1 warnings in efx_farch_handle_rx_not_ok
Some of these RX-event flags aren't used at all, so remove them.
Others are used only #ifdef DEBUG to log a message; suppress the
 unused-var warnings #ifndef DEBUG with a void cast.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:28:50 -07:00
David S. Miller bd10d45905 Merge branch 'Add-ip6_fragment-in-ipv6_stub'
wenxu says:

====================
Add ip6_fragment in ipv6_stub

Add ip6_fragment in ipv6_stub and use it in openvswitch
This version add default function eafnosupport_ipv6_fragment
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:26:39 -07:00
wenxu a7c978c6c9 openvswitch: using ip6_fragment in ipv6_stub
Using ipv6_stub->ipv6_fragment to avoid the netfilter dependency

Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:26:39 -07:00
wenxu 1d97898b36 ipv6: add ipv6_fragment hook in ipv6_stub
Add ipv6_fragment to ipv6_stub to avoid calling netfilter when
access ip6_fragment.

Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:26:39 -07:00
David S. Miller 353ff8ccad Merge branch 'gtp-minor-enhancements'
Nicolas Dichtel says:

====================
gtp: minor enhancements

The first patch removes a useless rcu lock and the second relax alloc
constraints when a PDP context is added.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:24:35 -07:00
Nicolas Dichtel 151ea46f3d gtp: relax alloc constraint when adding a pdp
When a PDP context is added, the rtnl lock is held, thus no need to force
a GFP_ATOMIC.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:24:34 -07:00
Nicolas Dichtel e2d1baca2b gtp: remove useless rcu_read_lock()
The rtnl lock is taken just the line above, no need to take the rcu also.

Fixes: 1788b8569f ("gtp: fix use-after-free in gtp_encap_destroy()")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:24:34 -07:00
Russell King e859a60add net: phylink: avoid oops during initialisation
If we intend to use PCS operations, mac_pcs_get_state() will not be
implemented, so will be NULL. If we also intend to register the PCS
operations in mac_prepare() or mac_config(), then this leads to an
attempt to call NULL function pointer during phylink_start(). Avoid
this, but we must report the link is down.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:23:16 -07:00
David S. Miller 3b44c79360 Merge branch 'hinic-add-debugfs-support'
Luo bin says:

====================
hinic: add debugfs support

add debugfs node for querying sq/rq info and function table
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:21:27 -07:00
Luo bin 5215e16244 hinic: add support to query function table
add debugfs node for querying function table, for example:
cat /sys/kernel/debug/hinic/0000:15:00.0/func_table/valid

Signed-off-by: Luo bin <luobin9@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:21:27 -07:00
Luo bin 626f060311 hinic: add support to query rq info
add debugfs node for querying rq info, for example:
cat /sys/kernel/debug/hinic/0000:15:00.0/RQs/0x0/rq_hw_pi

Signed-off-by: Luo bin <luobin9@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:21:27 -07:00
Luo bin 253ac3a979 hinic: add support to query sq info
add debugfs node for querying sq info, for example:
cat /sys/kernel/debug/hinic/0000:15:00.0/SQs/0x0/sq_pi

Signed-off-by: Luo bin <luobin9@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:21:26 -07:00
Johannes Berg c30a3c957c netlink: policy: correct validation type check
In the policy export for binary attributes I erroneously used
a != NLA_VALIDATE_NONE comparison instead of checking for the
two possible values, which meant that if a validation function
pointer ended up aliasing the min/max as negatives, we'd hit
a warning in nla_get_range_unsigned().

Fix this to correctly check for only the two types that should
be handled here, i.e. range with or without warn-too-long.

Reported-by: syzbot+353df1490da781637624@syzkaller.appspotmail.com
Fixes: 8aa26c575f ("netlink: make NLA_BINARY validation more flexible")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-31 12:01:15 -07:00
Alex Dewar 0f091e4331 netlabel: remove unused param from audit_log_format()
Commit d3b990b7f3 ("netlabel: fix problems with mapping removal")
added a check to return an error if ret_val != 0, before ret_val is
later used in a log message. Now it will unconditionally print "...
res=1". So just drop the check.

Addresses-Coverity: ("Dead code")
Fixes: d3b990b7f3 ("netlabel: fix problems with mapping removal")
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 09:08:51 -07:00
David S. Miller f3fb15b93a Merge branch 'ionic-memory-usage-rework'
Shannon Nelson says:

====================
ionic memory usage rework

Previous review comments have suggested [1],[2] that this driver
needs to rework how queue resources are managed and reconfigured
so that we don't do a full driver reset and to better handle
potential allocation failures.  This patchset is intended to
address those comments.

The first few patches clean some general issues and
simplify some of the memory structures.  The last 4 patches
specifically address queue parameter changes without a full
ionic_stop()/ionic_open().

[1] https://lore.kernel.org/netdev/20200706103305.182bd727@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com/
[2] https://lore.kernel.org/netdev/20200724.194417.2151242753657227232.davem@davemloft.net/

v3: use PTR_ALIGN without typecast
    fix up Neel's attribution

v2: use PTR_ALIGN
    recovery if netif_set_real_num_tx/rx_queues fails
    less racy queue bring up after reconfig
    common-ize the reconfig queue stop and start
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson 6f7d6f0fd7 ionic: pull reset_queues into tx_timeout handler
Convert tx_timeout handler to not do the full reset.  As this was
the last user of ionic_reset_queues(), we can drop it.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson 101b40a017 ionic: change queue count with no reset
Add to our new ionic_reconfigure_queues() to also be able to change
the number of queues in use, and to change the queue interrupt layout
between split and combined.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson a34e25ab97 ionic: change the descriptor ring length without full reset
The original way of changing ring length was to completely
tear down the lif's queue structure and then rebuild it, while
running the risk of allocations that might fail in the middle
and leave us with a broken driver.

Instead, we can set up all the new queue and descriptor
allocations first, then swap them out and delete the old
allocations.  If the new allocations fail, we report the error,
stay with the old setup and continue running.  This gives us
a safer path, and a smaller window of time where we're not
processing traffic.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson f053e1f870 ionic: change mtu without full queue rebuild
We really don't need to tear down and rebuild the whole queue structure
when changing the MTU; we can simply stop the queues, clean and refill,
then restart the queues.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson f1d2e894f1 ionic: use index not pointer for queue tracking
Use index counters rather than pointers for tracking head
and tail in the queues to save a little memory and to perhaps
slightly faster queue processing.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson ea5a8b09dc ionic: reduce contiguous memory allocation requirement
Split out the queue descriptor blocks into separate dma
allocations to make for smaller blocks.

Co-developed-by: Neel Patel <neel@pensando.io>
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson d4881430f5 ionic: clean up unnecessary non-static functions
ionic_open() and ionic_stop() are not referenced outside of their
defining file, so make them static.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson 34dec947b9 ionic: rework and simplify handling of the queue stats block
Use a block of stats structs attached to the lif instead of
little ones attached to each qcq.  This simplifies our memory
management and gets rid of a lot of unnecessary indirection.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson 30b87ab4c0 ionic: remove lif list concept
As we aren't yet supporting multiple lifs, we can remove
complexity by removing the list concept and related code,
to be re-engineered later when actually needed.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson ee205626af ionic: use kcalloc for new arrays
Use kcalloc for allocating arrays of structures.

Following along after
commit e71642009cbdA ("ionic_lif: Use devm_kcalloc() in ionic_qcq_alloc()")
there are a couple more array allocations that can be converted
to using devm_kcalloc().

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson 9aa1c152eb ionic: fix up a couple of debug strings
Fix the queue name displayed.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:30 -07:00
Shannon Nelson eba8760948 ionic: set MTU floor at ETH_MIN_MTU
The NIC might tell us its minimum MTU, but let's be sure not
to use something smaller than ETH_MIN_MTU.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 08:01:29 -07:00
David S. Miller 161e310667 Merge branch 'Enable-Fiber-on-DP83822-PHY'
Dan Murphy says:

====================
Enable Fiber on DP83822 PHY

The DP83822 Ethernet PHY has the ability to connect via a Fiber port.  The
derivative PHYs DP83825 and DP83826 do not have this ability. In fiber mode
the DP83822 disables auto negotiation and has a fixed 100Mbps speed with
support for full or half duplex modes.

A devicetree binding was added to set the signal polarity for the fiber
connection.  This property is only applicable if the FX_EN strap is set in
hardware other wise the signal loss detection is disabled on the PHY.

If the FX_EN is not strapped the device can be configured to run in fiber mode
via the device tree. All be it the PHY will not perform signal loss detection.

v2 review from a long time ago can be found here - https://lore.kernel.org/patchwork/patch/1270958/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-08-28 06:57:58 -07:00