Merge: cgroup/rstat: avoid disabling irqs for O(num_cpu)

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6931

Backporting upstream patch `cgroup/rstat: avoid disabling irqs for O(num_cpu)` to help address performance degradation issues.

JIRA: https://issues.redhat.com/browse/RHEL-94298

Signed-off-by: Radostin Stoyanov <[email protected]>

Approved-by: Herton R. Krzesinski <[email protected]>
Approved-by: Waiman Long <[email protected]>
Approved-by: Phil Auld <[email protected]>
Approved-by: CKI KWF Bot <[email protected]>

Merged-by: CKI GitLab Kmaint Pipeline Bot <[email protected]>

Author: CKI KWF Bot

kernel/cgroup/rstat.c

@@ -323,13 +323,11 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp)
 			rcu_read_unlock();
 		}
 
-		/* play nice and yield if necessary */
-		if (need_resched() || spin_needbreak(&cgroup_rstat_lock)) {
-			__cgroup_rstat_unlock(cgrp, cpu);
-			if (!cond_resched())
-				cpu_relax();
-			__cgroup_rstat_lock(cgrp, cpu);
-		}
+		/* play nice and avoid disabling interrupts for a long time */
+		__cgroup_rstat_unlock(cgrp, cpu);
+		if (!cond_resched())
+			cpu_relax();
+		__cgroup_rstat_lock(cgrp, cpu);
 	}
 }