[PATCH sched_ext/for-6.16 0/2] sched_ext: Extend usability of scx_bpf_select_cpu_and()

[Andrea Righi <arighi@nvidia.com>]

Many scx schedulers implement their own idle CPU selection policy, which
may be invoked from different contexts, not just from ops.select_cpu().

For example, some schedulers may need to trigger a proactive CPU wakeup
from ops.enqueue() after enqueuing a task, while others may expose this
functionality to user space, relying on a BPF test_run call to pick an idle
CPU.

To maintain a consistent selection policy, these schedulers often implement
their own idle CPU selection logic, since the built-in one is only usable
from ops.select_cpu(), leading to unnecessary code duplication and
fragmentation.

To address this, allow scx_bpf_select_cpu_and() to be used from any
context. This gives scx schedulers the option to use the built-in idle CPU
selection policy in a consistent way, potentially reducing code duplication
and fragmentation.

Andrea Righi (2):
      sched_ext: Make scx_kf_allowed_if_unlocked() available outside ext.c
      sched_ext/idle: Make scx_bpf_select_cpu_and() usable from any context

 kernel/sched/ext.c      |  5 -----
 kernel/sched/ext.h      |  5 +++++
 kernel/sched/ext_idle.c | 23 +++++++++++++++++------
 3 files changed, 22 insertions(+), 11 deletions(-)