The invocation of do_softirq() in flush_smp_call_function_from_idle()
breaks on RT because RT does not provide do_softirq().

Aside of that flush_smp_call_function_from_idle() is a misnomer since the
function is invoked not only from idle, but also from the scheduler
migration thread.

The following series addresses this. Changes vs. V4, which can be found
here: https://lore.kernel.org/lkml/20220412203649.956258017@linutronix.de

  - Fix a boatload of missing prototypes warning related to the
    scheduler and its header files.

Thanks,

	tglx
---
 include/linux/interrupt.h    |    9 +++++++++
 include/linux/sched.h        |    2 ++
 kernel/sched/build_policy.c  |    2 ++
 kernel/sched/build_utility.c |    1 +
 kernel/sched/core.c          |    5 ++++-
 kernel/sched/deadline.c      |    2 --
 kernel/sched/fair.c          |    1 +
 kernel/sched/idle.c          |    2 +-
 kernel/sched/sched.h         |    8 ++------
 kernel/sched/smp.h           |    6 ++++++
 kernel/smp.c                 |   32 ++++++++++++++++++++++++--------
 kernel/softirq.c             |   13 +++++++++++++
 kernel/stop_machine.c        |    2 --
 13 files changed, 65 insertions(+), 20 deletions(-)

On Wed, Apr 13, 2022 at 03:31:00PM +0200, Thomas Gleixner wrote:
>  include/linux/interrupt.h    |    9 +++++++++
>  include/linux/sched.h        |    2 ++
>  kernel/sched/build_policy.c  |    2 ++
>  kernel/sched/build_utility.c |    1 +
>  kernel/sched/core.c          |    5 ++++-
>  kernel/sched/deadline.c      |    2 --
>  kernel/sched/fair.c          |    1 +
>  kernel/sched/idle.c          |    2 +-
>  kernel/sched/sched.h         |    8 ++------
>  kernel/sched/smp.h           |    6 ++++++
>  kernel/smp.c                 |   32 ++++++++++++++++++++++++--------
>  kernel/softirq.c             |   13 +++++++++++++
>  kernel/stop_machine.c        |    2 --
>  13 files changed, 65 insertions(+), 20 deletions(-)

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>