linux-kernel - [PATCH] sched/fair: fix variable "done" set but not used

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Message-Id: <20190525161821.1025-1-cai@lca.pw>
Date:   Sat, 25 May 2019 12:18:21 -0400
From:   Qian Cai <cai@....pw>
To:     peterz@...radead.org, mingo@...nel.org
Cc:     vincent.guittot@...aro.org, linux-kernel@...r.kernel.org,
        Qian Cai <cai@....pw>
Subject: [PATCH] sched/fair: fix variable "done" set but not used

The commit f643ea220701 ("sched/nohz: Stop NOHZ stats when decayed")
introduced a compilation warning if CONFIG_NO_HZ_COMMON=n,

kernel/sched/fair.c: In function 'update_blocked_averages':
kernel/sched/fair.c:7750:7: warning: variable 'done' set but not used
[-Wunused-but-set-variable]

Fix it by adding a couple of "ifdef" macros as the variable is only
needed when CONFIG_NO_HZ_COMMON=y.

Signed-off-by: Qian Cai <cai@....pw>
---
 kernel/sched/fair.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f35930f5e528..c8682acf4508 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7747,7 +7747,9 @@ static void update_blocked_averages(int cpu)
 	struct cfs_rq *cfs_rq, *pos;
 	const struct sched_class *curr_class;
 	struct rq_flags rf;
+#ifdef CONFIG_NO_HZ_COMMON
 	bool done = true;
+#endif
 
 	rq_lock_irqsave(rq, &rf);
 	update_rq_clock(rq);
@@ -7774,20 +7776,22 @@ static void update_blocked_averages(int cpu)
 		if (cfs_rq_is_decayed(cfs_rq))
 			list_del_leaf_cfs_rq(cfs_rq);
 
+#ifdef CONFIG_NO_HZ_COMMON
 		/* Don't need periodic decay once load/util_avg are null */
 		if (cfs_rq_has_blocked(cfs_rq))
 			done = false;
 	}
+#endif
 
 	curr_class = rq->curr->sched_class;
 	update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
 	update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
 	update_irq_load_avg(rq, 0);
+#ifdef CONFIG_NO_HZ_COMMON
 	/* Don't need periodic decay once load/util_avg are null */
 	if (others_have_blocked(rq))
 		done = false;
 
-#ifdef CONFIG_NO_HZ_COMMON
 	rq->last_blocked_load_update_tick = jiffies;
 	if (done)
 		rq->has_blocked_load = 0;
-- 
2.20.1 (Apple Git-117)