Merge branch 'net-sched-load-modules-via-alias'

Merge branch 'net-sched-load-modules-via-alias'

Michal Koutný says:

====================
net/sched: Load modules via alias

These modules may be loaded lazily without user's awareness and
control. Add respective aliases to modules and request them under these
aliases so that modprobe's blacklisting mechanism (through aliases)
works for them. (The same pattern exists e.g. for filesystem
modules.)

For example (before the change):
  $ tc filter add dev lo parent 10: protocol ip prio 10 handle 1: cgroup
  # cls_cgroup module is loaded despite a `blacklist cls_cgroup` entry
  # in /etc/modprobe.d/*.conf

After the change:
  $ tc filter add dev lo parent 10: protocol ip prio 10 handle 1: cgroup
  Error: TC classifier not found.
  We have an error talking to the kernel
  # explicit/acknowledged (privileged) action is needed
  $ modprobe cls_cgroup
  # blacklist entry won't apply to this direct modprobe, module is
  # loaded with awareness

A considered alternative was invoking `modprobe -b` always from
request_module(), however, dismissed as too intrusive and slightly
confusing in favor of the precedented aliases (the commit 7f78e0351394
("fs: Limit sys_mount to only request filesystem modules.").

User experience suffers in both alternatives. Its improvement is
orthogonal to blacklist honoring.

v1: https://lore.kernel.org/r/20231121175640.9981-1-mkoutny@suse.com
v2 https://lore.kernel.org/r/20231206192752.18989-1-mkoutny@suse.com
v3 https://lore.kernel.org/r/20240112180646.13232-1-mkoutny@suse.com
v4 https://lore.kernel.org/r/20240123135242.11430-1-mkoutny@suse.com

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
====================

Link: https://lore.kernel.org/r/20240201130943.19536-1-mkoutny@suse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>