linux-kernel - [PATCH v3 3/6] sched: fair: move unused stub functions to header

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Message-Id: <20231123110506.707903-4-arnd@kernel.org>
Date:   Thu, 23 Nov 2023 12:05:03 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>,
        David Woodhouse <dwmw2@...radead.org>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Matt Turner <mattst88@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nicolas Schier <nicolas@...sle.eu>,
        Peter Zijlstra <peterz@...radead.org>,
        Rich Felker <dalias@...c.org>,
        Richard Henderson <richard.henderson@...aro.org>,
        Richard Weinberger <richard@....at>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Tudor Ambarus <tudor.ambarus@...aro.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        linux-arch@...r.kernel.org, linux-alpha@...r.kernel.org,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-sh@...r.kernel.org, linux-usb@...r.kernel.org,
        sparclinux@...r.kernel.org, x86@...nel.org
Subject: [PATCH v3 3/6] sched: fair: move unused stub functions to header

From: Arnd Bergmann <arnd@...db.de>

These four functions have a normal definition for CONFIG_FAIR_GROUP_SCHED,
and empty one that is only referenced when FAIR_GROUP_SCHED is disabled
but CGROUP_SCHED is still enabled. If both are turned off, the functions
are still defined but the misisng prototype causes a W=1 warning:

kernel/sched/fair.c:12544:6: error: no previous prototype for 'free_fair_sched_group'
kernel/sched/fair.c:12546:5: error: no previous prototype for 'alloc_fair_sched_group'
kernel/sched/fair.c:12553:6: error: no previous prototype for 'online_fair_sched_group'
kernel/sched/fair.c:12555:6: error: no previous prototype for 'unregister_fair_sched_group'

Move the alternatives into the header as static inline functions with
the correct combination of #ifdef checks to avoid the warning without
adding even more complexity.

[A different patch with the same description got applied by accident
 and was later reverted, but the original patch is still missing]

Fixes: 7aa55f2a5902 ("sched/fair: Move unused stub functions to header")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 kernel/sched/fair.c  | 13 -------------
 kernel/sched/sched.h | 11 +++++++++++
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 07f555857698..cb68d71c81bc 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -13040,19 +13040,6 @@ int sched_group_set_idle(struct task_group *tg, long idle)
 	return 0;
 }
 
-#else /* CONFIG_FAIR_GROUP_SCHED */
-
-void free_fair_sched_group(struct task_group *tg) { }
-
-int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
-{
-	return 1;
-}
-
-void online_fair_sched_group(struct task_group *tg) { }
-
-void unregister_fair_sched_group(struct task_group *tg) { }
-
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 8a70d51ffa33..eb7e07a1abcc 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -461,10 +461,21 @@ static inline int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
 
 extern int tg_nop(struct task_group *tg, void *data);
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
 extern void free_fair_sched_group(struct task_group *tg);
 extern int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent);
 extern void online_fair_sched_group(struct task_group *tg);
 extern void unregister_fair_sched_group(struct task_group *tg);
+#else
+static inline void free_fair_sched_group(struct task_group *tg) { }
+static inline int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
+{
+       return 1;
+}
+static inline void online_fair_sched_group(struct task_group *tg) { }
+static inline void unregister_fair_sched_group(struct task_group *tg) { }
+#endif
+
 extern void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
 			struct sched_entity *se, int cpu,
 			struct sched_entity *parent);
-- 
2.39.2