Fix a memory leak issue on netpoll and create a netconsole test that exposes
the problem, when run with kmemleak enabled.

This is a merge of two patches I've sent individually and are merged on
the same patchset[1][2].

Link: https://lore.kernel.org/all/20250904-netconsole_torture-v2-0-5775ed5dc366@debian.org/ [1]
Link: https://lore.kernel.org/all/20250902165426.6d6cd172@kernel.org/ [2]

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changes in v3:
- this patchset is a merge of the fix and the selftest together as
recommended by Jakub.

Changes in v2:
- Reuse the netconsole creation from lib_netcons.sh. Thus, refactoring
  the create_dynamic_target() (Jakub)
- Move the "wait" to after all the messages has been sent.
- Link to v1: https://lore.kernel.org/r/20250902-netconsole_torture-v1-1-03c6066598e9@debian.org

---
Breno Leitao (3):
      netpoll: fix incorrect refcount handling causing incorrect cleanup
      selftest: netcons: refactor target creation
      selftest: netcons: create a torture test

 net/core/netpoll.c                                 |   7 +-
 tools/testing/selftests/drivers/net/Makefile       |   1 +
 .../selftests/drivers/net/lib/sh/lib_netcons.sh    |  30 +++--
 .../selftests/drivers/net/netcons_torture.sh       | 127 +++++++++++++++++++++
 4 files changed, 152 insertions(+), 13 deletions(-)
---
base-commit: d69eb204c255c35abd9e8cb621484e8074c75eaa
change-id: 20250902-netconsole_torture-8fc23f0aca99

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