sched/uclamp: Reset uclamp values on RESET_ON_FORK

A forked tasks gets the same clamp values of its parent however, when
the RESET_ON_FORK flag is set on parent, e.g. via:

   sys_sched_setattr()
      sched_setattr()
         __sched_setscheduler(attr::SCHED_FLAG_RESET_ON_FORK)

the new forked task is expected to start with all attributes reset to
default values.

Do that for utilization clamp values too by checking the reset request
from the existing uclamp_fork() call which already provides the required
initialization for other uclamp related bits.

Signed-off-by: Patrick Bellasi <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alessio Balsini <[email protected]>
Cc: Dietmar Eggemann <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Morten Rasmussen <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Quentin Perret <[email protected]>
Cc: Rafael J . Wysocki <[email protected]>
Cc: Steve Muckle <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Todd Kjos <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: Viresh Kumar <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: derkling

kernel/sched/core.c

@@ -1082,6 +1082,14 @@ static void uclamp_fork(struct task_struct *p)
 
 	for_each_clamp_id(clamp_id)
 		p->uclamp[clamp_id].active = false;
+
+	if (likely(!p->sched_reset_on_fork))
+		return;
+
+	for_each_clamp_id(clamp_id) {
+		uclamp_se_set(&p->uclamp_req[clamp_id],
+			      uclamp_none(clamp_id), false);
+	}
 }
 
 static void __init init_uclamp(void)