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  1. 02 11月, 2021 1 次提交
    • J
      net: arp: introduce arp_evict_nocarrier sysctl parameter · fcdb44d0
      由 James Prestwood 提交于 
      This change introduces a new sysctl parameter, arp_evict_nocarrier.
When set (default) the ARP cache will be cleared on a NOCARRIER event.
This new option has been defaulted to '1' which maintains existing
behavior.

Clearing the ARP cache on NOCARRIER is relatively new, introduced by:

commit 859bd2ef
Author: David Ahern <dsahern@gmail.com>
Date:   Thu Oct 11 20:33:49 2018 -0700

    net: Evict neighbor entries on carrier down

The reason for this changes is to prevent the ARP cache from being
cleared when a wireless device roams. Specifically for wireless roams
the ARP cache should not be cleared because the underlying network has not
changed. Clearing the ARP cache in this case can introduce significant
delays sending out packets after a roam.

A user reported such a situation here:

https://lore.kernel.org/linux-wireless/CACsRnHWa47zpx3D1oDq9JYnZWniS8yBwW1h0WAVZ6vrbwL_S0w@mail.gmail.com/

After some investigation it was found that the kernel was holding onto
packets until ARP finished which resulted in this 1 second delay. It
was also found that the first ARP who-has was never responded to,
which is actually what caues the delay. This change is more or less
working around this behavior, but again, there is no reason to clear
the cache on a roam anyways.

As for the unanswered who-has, we know the packet made it OTA since
it was seen while monitoring. Why it never received a response is
unknown. In any case, since this is a problem on the AP side of things
all that can be done is to work around it until it is solved.

Some background on testing/reproducing the packet delay:

Hardware:
 - 2 access points configured for Fast BSS Transition (Though I don't
   see why regular reassociation wouldn't have the same behavior)
 - Wireless station running IWD as supplicant
 - A device on network able to respond to pings (I used one of the APs)

Procedure:
 - Connect to first AP
 - Ping once to establish an ARP entry
 - Start a tcpdump
 - Roam to second AP
 - Wait for operstate UP event, and note the timestamp
 - Start pinging

Results:

Below is the tcpdump after UP. It was recorded the interface went UP at
10:42:01.432875.

10:42:01.461871 ARP, Request who-has 192.168.254.1 tell 192.168.254.71, length 28
10:42:02.497976 ARP, Request who-has 192.168.254.1 tell 192.168.254.71, length 28
10:42:02.507162 ARP, Reply 192.168.254.1 is-at ac:86:74:55:b0:20, length 46
10:42:02.507185 IP 192.168.254.71 > 192.168.254.1: ICMP echo request, id 52792, seq 1, length 64
10:42:02.507205 IP 192.168.254.71 > 192.168.254.1: ICMP echo request, id 52792, seq 2, length 64
10:42:02.507212 IP 192.168.254.71 > 192.168.254.1: ICMP echo request, id 52792, seq 3, length 64
10:42:02.507219 IP 192.168.254.71 > 192.168.254.1: ICMP echo request, id 52792, seq 4, length 64
10:42:02.507225 IP 192.168.254.71 > 192.168.254.1: ICMP echo request, id 52792, seq 5, length 64
10:42:02.507232 IP 192.168.254.71 > 192.168.254.1: ICMP echo request, id 52792, seq 6, length 64
10:42:02.515373 IP 192.168.254.1 > 192.168.254.71: ICMP echo reply, id 52792, seq 1, length 64
10:42:02.521399 IP 192.168.254.1 > 192.168.254.71: ICMP echo reply, id 52792, seq 2, length 64
10:42:02.521612 IP 192.168.254.1 > 192.168.254.71: ICMP echo reply, id 52792, seq 3, length 64
10:42:02.521941 IP 192.168.254.1 > 192.168.254.71: ICMP echo reply, id 52792, seq 4, length 64
10:42:02.522419 IP 192.168.254.1 > 192.168.254.71: ICMP echo reply, id 52792, seq 5, length 64
10:42:02.523085 IP 192.168.254.1 > 192.168.254.71: ICMP echo reply, id 52792, seq 6, length 64

You can see the first ARP who-has went out very quickly after UP, but
was never responded to. Nearly a second later the kernel retries and
gets a response. Only then do the ping packets go out. If an ARP entry
is manually added prior to UP (after the cache is cleared) it is seen
that the first ping is never responded to, so its not only an issue with
ARP but with data packets in general.

As mentioned prior, the wireless interface was also monitored to verify
the ping/ARP packet made it OTA which was observed to be true.
Signed-off-by: NJames Prestwood <prestwoj@gmail.com>
Reviewed-by: NDavid Ahern <dsahern@kernel.org>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
      fcdb44d0
  3. 29 10月, 2021 2 次提交
  5. 28 10月, 2021 2 次提交
  7. 27 10月, 2021 1 次提交
  9. 26 10月, 2021 6 次提交
  11. 24 10月, 2021 2 次提交
  13. 22 10月, 2021 2 次提交
  15. 20 10月, 2021 4 次提交
  17. 18 10月, 2021 3 次提交
  19. 15 10月, 2021 8 次提交
  21. 14 10月, 2021 2 次提交
  23. 13 10月, 2021 1 次提交
  25. 09 10月, 2021 2 次提交
  27. 08 10月, 2021 2 次提交
  29. 07 10月, 2021 2 次提交
    • I
      ethtool: Add transceiver module extended state · 3dfb5112
      由 Ido Schimmel 提交于 
      Add an extended state and sub-state to describe link issues related to
transceiver modules.

The 'ETHTOOL_LINK_EXT_SUBSTATE_MODULE_CMIS_NOT_READY' extended sub-state
tells user space that port is unable to gain a carrier because the CMIS
Module State Machine did not reach the ModuleReady (Fully Operational)
state. For example, if the module is stuck at ModuleLowPwr or
ModuleFault state. In case of the latter, user space can read the fault
reason from the module's EEPROM and potentially reset it.
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
      3dfb5112
    • I
      ethtool: Add ability to control transceiver modules' power mode · 353407d9
      由 Ido Schimmel 提交于 
      Add a pair of new ethtool messages, 'ETHTOOL_MSG_MODULE_SET' and
'ETHTOOL_MSG_MODULE_GET', that can be used to control transceiver
modules parameters and retrieve their status.

The first parameter to control is the power mode of the module. It is
only relevant for paged memory modules, as flat memory modules always
operate in low power mode.

When a paged memory module is in low power mode, its power consumption
is reduced to the minimum, the management interface towards the host is
available and the data path is deactivated.

User space can choose to put modules that are not currently in use in
low power mode and transition them to high power mode before putting the
associated ports administratively up. This is useful for user space that
favors reduced power consumption and lower temperatures over reduced
link up times. In QSFP-DD modules the transition from low power mode to
high power mode can take a few seconds and this transition is only
expected to get longer with future / more complex modules.

User space can control the power mode of the module via the power mode
policy attribute ('ETHTOOL_A_MODULE_POWER_MODE_POLICY'). Possible
values:

* high: Module is always in high power mode.

* auto: Module is transitioned by the host to high power mode when the
  first port using it is put administratively up and to low power mode
  when the last port using it is put administratively down.

The operational power mode of the module is available to user space via
the 'ETHTOOL_A_MODULE_POWER_MODE' attribute. The attribute is not
reported to user space when a module is not plugged-in.

The user API is designed to be generic enough so that it could be used
for modules with different memory maps (e.g., SFF-8636, CMIS).

The only implementation of the device driver API in this series is for a
MAC driver (mlxsw) where the module is controlled by the device's
firmware, but it is designed to be generic enough so that it could also
be used by implementations where the module is controlled by the CPU.

CMIS testing
============

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x03 (ModuleReady)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : Off

The module is not in low power mode, as it is not forced by hardware
(LowPwrAllowRequestHW is off) or by software (LowPwrRequestSW is off).

The power mode can be queried from the kernel. In case
LowPwrAllowRequestHW was on, the kernel would need to take into account
the state of the LowPwrRequestHW signal, which is not visible to user
space.

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy high
 power-mode high

Change the power mode policy to 'auto':

 # ethtool --set-module swp11 power-mode-policy auto

Query the power mode again:

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x01 (ModuleLowPwr)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : On

Put the associated port administratively up which will instruct the host
to transition the module to high power mode:

 # ip link set dev swp11 up

Query the power mode again:

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy auto
 power-mode high

Verify with the data read from the EEPROM:

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x03 (ModuleReady)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : Off

Put the associated port administratively down which will instruct the
host to transition the module to low power mode:

 # ip link set dev swp11 down

Query the power mode again:

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x01 (ModuleLowPwr)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : On

SFF-8636 testing
================

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 ...
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) enabled
 Power set                                 : Off
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.7733 mW / -1.12 dBm
 Transmit avg optical power (Channel 2)    : 0.7649 mW / -1.16 dBm
 Transmit avg optical power (Channel 3)    : 0.7790 mW / -1.08 dBm
 Transmit avg optical power (Channel 4)    : 0.7837 mW / -1.06 dBm
 Rcvr signal avg optical power(Channel 1)  : 0.9302 mW / -0.31 dBm
 Rcvr signal avg optical power(Channel 2)  : 0.9079 mW / -0.42 dBm
 Rcvr signal avg optical power(Channel 3)  : 0.8993 mW / -0.46 dBm
 Rcvr signal avg optical power(Channel 4)  : 0.8778 mW / -0.57 dBm

The module is not in low power mode, as it is not forced by hardware
(Power override is on) or by software (Power set is off).

The power mode can be queried from the kernel. In case Power override
was off, the kernel would need to take into account the state of the
LPMode signal, which is not visible to user space.

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy high
 power-mode high

Change the power mode policy to 'auto':

 # ethtool --set-module swp13 power-mode-policy auto

Query the power mode again:

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) not enabled
 Power set                                 : On
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 2)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 3)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 4)    : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 1)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 2)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 3)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 4)  : 0.0000 mW / -inf dBm

Put the associated port administratively up which will instruct the host
to transition the module to high power mode:

 # ip link set dev swp13 up

Query the power mode again:

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy auto
 power-mode high

Verify with the data read from the EEPROM:

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 ...
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) enabled
 Power set                                 : Off
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.7934 mW / -1.01 dBm
 Transmit avg optical power (Channel 2)    : 0.7859 mW / -1.05 dBm
 Transmit avg optical power (Channel 3)    : 0.7885 mW / -1.03 dBm
 Transmit avg optical power (Channel 4)    : 0.7985 mW / -0.98 dBm
 Rcvr signal avg optical power(Channel 1)  : 0.9325 mW / -0.30 dBm
 Rcvr signal avg optical power(Channel 2)  : 0.9034 mW / -0.44 dBm
 Rcvr signal avg optical power(Channel 3)  : 0.9086 mW / -0.42 dBm
 Rcvr signal avg optical power(Channel 4)  : 0.8885 mW / -0.51 dBm

Put the associated port administratively down which will instruct the
host to transition the module to low power mode:

 # ip link set dev swp13 down

Query the power mode again:

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 ...
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) not enabled
 Power set                                 : On
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 2)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 3)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 4)    : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 1)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 2)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 3)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 4)  : 0.0000 mW / -inf dBm
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
      353407d9