Revert "cpuacct: reduce one NULL check in fast-path"

This reverts commit 7a46c594.

This was applied to the x86 tree mistakenly, it belongs into the
scheduler tree.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -10001,11 +10001,10 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 	cpu = task_cpu(tsk);
 	ca = task_ca(tsk);
 
-	do {
+	for (; ca; ca = ca->parent) {
 		u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 		*cpuusage += cputime;
-		ca = ca->parent;
-	} while (ca);
+	}
 }
 
 struct cgroup_subsys cpuacct_subsys = {