[PATCH net-next v2 0/3] Misc vlan cleanups

[Gal Pressman <gal@nvidia.com>]

This patch series addresses compilation issues with objtool when VLAN
support is disabled (CONFIG_VLAN_8021Q=n) and makes related improvements
to the VLAN infrastructure.

When CONFIG_VLAN_8021Q=n, CONFIG_OBJTOOL=y, and CONFIG_OBJTOOL_WERROR=y,
the following compilation error occurs:

drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.o: error: objtool: parse_mirred.isra.0+0x370: mlx5e_tc_act_vlan_add_push_action() missing __noreturn in .c/.h or NORETURN() in noreturns.h

The error occurs because objtool cannot determine that unreachable BUG()
calls in VLAN code paths are actually dead code when VLAN support is
disabled.

First patch makes is_vlan_dev() a stub when VLAN is not configured,
allows compile-out of VLAN-dependent dead code paths and resolves the
objtool compilation error.

Second patch replaces BUG() calls with WARN_ON_ONCE(), as the usage of
BUG() should be avoided.

Third patch uses the "kernel" way of testing whether an option is
configured as builtin/module, instead of open-coding it.

Changelog -
v1->v2: https://lore.kernel.org/netdev/20250610072611.1647593-1-gal@nvidia.com/
* Add the first patch, alternative approach suggested by Jakub

Gal Pressman (3):
  net: vlan: Make is_vlan_dev() a stub when VLAN is not configured
  net: vlan: Replace BUG() with WARN_ON_ONCE() in vlan_dev_* stubs
  net: vlan: Use IS_ENABLED() helper for CONFIG_VLAN_8021Q guard

 include/linux/if_vlan.h | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

-- 
2.40.1