Merge branch 'net-ipv4-allow-directed-broadcast-routes-to-use-dst-hint'

Oscar Maes says:

====================
net: ipv4: allow directed broadcast routes to use dst hint

Currently, ip_extract_route_hint uses RTN_BROADCAST to decide
whether to use the route dst hint mechanism.

This check is too strict, as it prevents directed broadcast
routes from using the hint, resulting in poor performance
during bursts of directed broadcast traffic.

This series fixes this, and adds a new selftest to ensure
this does not regress.

Link to v2: https://lore.kernel.org/20250814140309.3742-1-oscmaes92@gmail.com
====================

Link: https://patch.msgid.link/20250819174642.5148-1-oscmaes92@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>