linux-kernel - [PATCH v2] sched/core: clean up sched

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Message-Id: <1559681162-5385-1-git-send-email-cai@lca.pw>
Date:   Tue,  4 Jun 2019 16:46:02 -0400
From:   Qian Cai <cai@....pw>
To:     akpm@...ux-foundation.org
Cc:     mingo@...nel.org, peterz@...radead.org,
        torvalds@...ux-foundation.org, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, Qian Cai <cai@....pw>
Subject: [PATCH v2] sched/core: clean up sched_init() a bit

Compiling a kernel with both FAIR_GROUP_SCHED=n and RT_GROUP_SCHED=n
will generate a warning using W=1:

  kernel/sched/core.c: In function 'sched_init':
  kernel/sched/core.c:5906:32: warning: variable 'ptr' set but not used

Use this opportunity to tidy up a code a bit by removing unnecssary
indentations, #endif comments and lines.

Signed-off-by: Qian Cai <cai@....pw>
---

v2: Fix an oversight when both FAIR_GROUP_SCHED and RT_GROUP_SCHED
    selected which was found by the 0day kernel testing robot.

 kernel/sched/core.c | 50 +++++++++++++++++++++++---------------------------
 1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 874c427742a9..edebd5e97542 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5903,36 +5903,31 @@ int in_sched_functions(unsigned long addr)
 void __init sched_init(void)
 {
 	int i, j;
-	unsigned long alloc_size = 0, ptr;
-
-	wait_bit_init();
-
-#ifdef CONFIG_FAIR_GROUP_SCHED
-	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
+#if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_RT_GROUP_SCHED)
+	unsigned long alloc_size = 4 * nr_cpu_ids * sizeof(void **);
+	unsigned long ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
+#elif defined(CONFIG_FAIR_GROUP_SCHED) || defined(CONFIG_RT_GROUP_SCHED)
+	unsigned long alloc_size = 2 * nr_cpu_ids * sizeof(void **);
+	unsigned long ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
 #endif
-#ifdef CONFIG_RT_GROUP_SCHED
-	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
-#endif
-	if (alloc_size) {
-		ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
+	wait_bit_init();
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-		root_task_group.se = (struct sched_entity **)ptr;
-		ptr += nr_cpu_ids * sizeof(void **);
+	root_task_group.se = (struct sched_entity **)ptr;
+	ptr += nr_cpu_ids * sizeof(void **);
 
-		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
-		ptr += nr_cpu_ids * sizeof(void **);
+	root_task_group.cfs_rq = (struct cfs_rq **)ptr;
+	ptr += nr_cpu_ids * sizeof(void **);
 
-#endif /* CONFIG_FAIR_GROUP_SCHED */
+#endif
 #ifdef CONFIG_RT_GROUP_SCHED
-		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
-		ptr += nr_cpu_ids * sizeof(void **);
+	root_task_group.rt_se = (struct sched_rt_entity **)ptr;
+	ptr += nr_cpu_ids * sizeof(void **);
 
-		root_task_group.rt_rq = (struct rt_rq **)ptr;
-		ptr += nr_cpu_ids * sizeof(void **);
+	root_task_group.rt_rq = (struct rt_rq **)ptr;
+	ptr += nr_cpu_ids * sizeof(void **);
 
-#endif /* CONFIG_RT_GROUP_SCHED */
-	}
+#endif
 #ifdef CONFIG_CPUMASK_OFFSTACK
 	for_each_possible_cpu(i) {
 		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
@@ -5940,7 +5935,7 @@ void __init sched_init(void)
 		per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
 			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
 	}
-#endif /* CONFIG_CPUMASK_OFFSTACK */
+#endif
 
 	init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
 	init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime());
@@ -5950,9 +5945,9 @@ void __init sched_init(void)
 #endif
 
 #ifdef CONFIG_RT_GROUP_SCHED
-	init_rt_bandwidth(&root_task_group.rt_bandwidth,
-			global_rt_period(), global_rt_runtime());
-#endif /* CONFIG_RT_GROUP_SCHED */
+	init_rt_bandwidth(&root_task_group.rt_bandwidth, global_rt_period(),
+			  global_rt_runtime());
+#endif
 
 #ifdef CONFIG_CGROUP_SCHED
 	task_group_cache = KMEM_CACHE(task_group, 0);
@@ -5961,7 +5956,7 @@ void __init sched_init(void)
 	INIT_LIST_HEAD(&root_task_group.children);
 	INIT_LIST_HEAD(&root_task_group.siblings);
 	autogroup_init(&init_task);
-#endif /* CONFIG_CGROUP_SCHED */
+#endif
 
 	for_each_possible_cpu(i) {
 		struct rq *rq;
@@ -6031,6 +6026,7 @@ void __init sched_init(void)
 		rq->last_blocked_load_update_tick = jiffies;
 		atomic_set(&rq->nohz_flags, 0);
 #endif
+
 #endif /* CONFIG_SMP */
 		hrtick_rq_init(rq);
 		atomic_set(&rq->nr_iowait, 0);
-- 
1.8.3.1