[net-next,v04,0/3] net: af_packet: allow joining a fanout when link is down

Message

Gur Stavi Oct. 13, 2024, 7:15 a.m. UTC

PACKET socket can retain its fanout membership through link down and up
and leave a fanout while closed regardless of link state.
However, socket was forbidden from joining a fanout while it was not
RUNNING.

This scenario was identified while studying DPDK pmd_af_packet_drv.
Since sockets are only created during initialization, there is no reason
to fail the initialization if a single link is temporarily down.

This patch allows PACKET socket to join a fanout while not RUNNING.

Selftest psock_fanout is extended to test this "fanout while link down"
scenario.

Selftest psock_fanout is also extended to test fanout create/join by
socket that did not bind or specified a protocol, which carries an
implicit bind.

This is the only test that was performed.

Changes:

V04:
* Minimized code change.
* Removed test of ifindex. A socket that went through bind "unlisted" race can
  join a fanout.

V03: https://lore.kernel.org/netdev/[e-mail]
* psock_fanout: add test for joining fanout with unbound socket.
* Test that socket can receive packets before adding it to a fanout match.
  This is kind of replaces the RUNNING test that was removed.
* Initialize po->ifindex in packet_create. To -1 if no protocol is specified
  and add an explicit initialization to 0 if protocol is specified.
* Refactor relevant code in fanout_add within bind_lock, as a sequence of
  if {} else if {}, in order to reduce indentation of nested if statements and
  provide specific error codes.

V02: https://lore.kernel.org/netdev/[e-mail]
* psock_fanout: use explicit loopback up/down instead of toggle.
* psock_fanout: don't try to restore loopback state on failure.
* Rephrase commit message about "leaving a fanout".

V01: https://lore.kernel.org/netdev/[e-mail]/

Gur Stavi (3):
  af_packet: allow fanout_add when socket is not RUNNING
  selftests: net/psock_fanout: socket joins fanout when link is down
  selftests: net/psock_fanout: unbound socket fanout

 net/packet/af_packet.c                     |  9 +--
 tools/testing/selftests/net/psock_fanout.c | 78 +++++++++++++++++++++-
 2 files changed, 80 insertions(+), 7 deletions(-)


base-commit: c531f2269a53db5cf64b24baf785ccbcda52970f

Comments

[e-mail] Oct. 15, 2024, 5 p.m. UTC | #1

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <[e-mail]>:

On Sun, 13 Oct 2024 10:15:24 +0300 you wrote:
> PACKET socket can retain its fanout membership through link down and up
> and leave a fanout while closed regardless of link state.
> However, socket was forbidden from joining a fanout while it was not
> RUNNING.
> 
> This scenario was identified while studying DPDK pmd_af_packet_drv.
> Since sockets are only created during initialization, there is no reason
> to fail the initialization if a single link is temporarily down.
> 
> [...]

Here is the summary with links:
  - [net-next,v04,1/3] af_packet: allow fanout_add when socket is not RUNNING
    https://git.kernel.org/netdev/net-next/c/2cee3e6e2e4b
  - [net-next,v04,2/3] selftests: net/psock_fanout: socket joins fanout when link is down
    https://git.kernel.org/netdev/net-next/c/9317e8933e27
  - [net-next,v04,3/3] selftests: net/psock_fanout: unbound socket fanout
    https://git.kernel.org/netdev/net-next/c/7ec02a3aef05

You are awesome, thank you!