linux-kernel - [PATCH v2] sched: fix "runnable_avg_yN

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Message-Id: <1559596304-31581-1-git-send-email-cai@lca.pw>
Date:   Mon,  3 Jun 2019 17:11:44 -0400
From:   Qian Cai <cai@....pw>
To:     mingo@...hat.com
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        Qian Cai <cai@....pw>
Subject: [PATCH v2] sched: fix "runnable_avg_yN_inv" not used warnings

runnable_avg_yN_inv[] is only used in kernel/sched/pelt.c but was
included in several other places because they need other macros all
came from kernel/sched/sched-pelt.h which was generated by
Documentation/scheduler/sched-pelt. As the result, it causes compilation
a lot of warnings,

In file included from kernel/sched/pelt.h:2,
                 from kernel/sched/rt.c:8:
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined
but not used [-Wunused-const-variable=]
In file included from kernel/sched/pelt.h:2,
                 from kernel/sched/fair.c:705:
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined
but not used [-Wunused-const-variable=]
In file included from kernel/sched/pelt.h:2,
                 from kernel/sched/deadline.c:19:
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined
but not used [-Wunused-const-variable=]

Silence it by appending the __maybe_unused attribute for it, so all
generated variables and macros can still be kept in the same file.

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

v2: add a comment for __maybe_unused.

 Documentation/scheduler/sched-pelt.c | 3 ++-
 kernel/sched/sched-pelt.h            | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/scheduler/sched-pelt.c b/Documentation/scheduler/sched-pelt.c
index e4219139386a..7238b355919c 100644
--- a/Documentation/scheduler/sched-pelt.c
+++ b/Documentation/scheduler/sched-pelt.c
@@ -20,7 +20,8 @@ void calc_runnable_avg_yN_inv(void)
 	int i;
 	unsigned int x;
 
-	printf("static const u32 runnable_avg_yN_inv[] = {");
+	/* To silence -Wunused-but-set-variable warnings. */
+	printf("static const u32 runnable_avg_yN_inv[] __maybe_unused = {");
 	for (i = 0; i < HALFLIFE; i++) {
 		x = ((1UL<<32)-1)*pow(y, i);
 
diff --git a/kernel/sched/sched-pelt.h b/kernel/sched/sched-pelt.h
index a26473674fb7..c529706bed11 100644
--- a/kernel/sched/sched-pelt.h
+++ b/kernel/sched/sched-pelt.h
@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /* Generated by Documentation/scheduler/sched-pelt; do not modify. */
 
-static const u32 runnable_avg_yN_inv[] = {
+static const u32 runnable_avg_yN_inv[] __maybe_unused = {
 	0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
 	0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
 	0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
-- 
1.8.3.1