[PATCH net-next 0/2] netconsole: replace target_list_lock by RCU on userdata hot path

[Breno Leitao <leitao@debian.org>]

I would like to move netconsole to use RCU on the hot path for
a while instead of target_list_lock. My goal is to have no lock on the
tx side at all and eventually drop CON_NBCON_ATOMIC_UNSAFE, if that is
possible [1].

Start removing target_list_lock on certain parts of the code. This patch
transform the userdata array into a RCU-protected pointer, and use the
dynamic mutex as the write lock.

Added a selftest, given we didn't have any netconsole selftest for
userdata operations. Feel free to drop it if this is not user, dear
maintainers.

Link: https://lore.kernel.org/all/20251121-nbcon-v1-0-503d17b2b4af@debian.org/[1]

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Breno Leitao (2):
      netconsole: publish the userdata payload with RCU
      selftests: netconsole: add a userdata torture test

 drivers/net/netconsole.c                           |  88 ++++----
 .../selftests/drivers/net/netconsole/Makefile      |   1 +
 .../drivers/net/netconsole/netcons_userdata.sh     | 224 +++++++++++++++++++++
 3 files changed, 279 insertions(+), 34 deletions(-)
---
base-commit: 8ba098e6b6ff0db8edf28528d1552be261af30d4
change-id: 20260801-netcons-userdata-rcu-40446e018f86

Best regards,
--  
Breno Leitao <leitao@debian.org>