sched/deadline: Use online cpus for validating runtime

[ Upstream commit 14672f0 ]

The ftrace selftest reported a failure because writing -1 to
sched_rt_runtime_us returns -EBUSY. This happens when the possible
CPUs are different from active CPUs.

Active CPUs are part of one root domain, while remaining CPUs are part
of def_root_domain. Since active cpumask is being used, this results in
cpus=0 when a non active CPUs is used in the loop.

Fix it by looping over the online CPUs instead for validating the
bandwidth calculations.

Signed-off-by: Shrikanth Hegde <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Juri Lelli <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sasha Levin <[email protected]>
(cherry picked from commit 0ab44f03c50fceb8c8bd27ea9b61039c5c611cf0)
Signed-off-by: Alok Tiwari <[email protected]>

Author: Shrikanth Hegde

kernel/sched/deadline.c

@@ -2521,7 +2521,7 @@ int sched_dl_global_validate(void)
 	 * cycling on root_domains... Discussion on different/better
 	 * solutions is welcome!
 	 */
-	for_each_possible_cpu(cpu) {
+	for_each_online_cpu(cpu) {
 		rcu_read_lock_sched();
 		dl_b = dl_bw_of(cpu);
 		cpus = dl_bw_cpus(cpu);