linux-kernel - [PATCH v1 1/1] sched/fair: Mark cfs_bandwidth_used() and m*_vruntime() with __maybe

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Message-ID: <20240905171210.267626-1-andriy.shevchenko@linux.intel.com>
Date: Thu,  5 Sep 2024 20:12:10 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Ingo Molnar <mingo@...nel.org>,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Cc: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v1 1/1] sched/fair: Mark cfs_bandwidth_used() and m*_vruntime() with __maybe_unused

When cfs_bandwidth_used() is unused, it prevents kernel builds
with clang, `make W=1` and CONFIG_WERROR=y:

kernel/sched/fair.c:526:19: error: unused function 'max_vruntime' [-Werror,-Wunused-function]
  526 | static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
      |                   ^~~~~~~~~~~~
kernel/sched/fair.c:6580:20: error: unused function 'cfs_bandwidth_used' [-Werror,-Wunused-function]
 6580 | static inline bool cfs_bandwidth_used(void)
      |                    ^~~~~~~~~~~~~~~~~~

Fix this by marking them with __maybe_unused (all cases for the sake of
symmetry).

See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
inline functions for W=1 build").

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 kernel/sched/fair.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9057584ec06d..b9d35675db50 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -523,7 +523,7 @@ void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec);
  * Scheduling class tree data structure manipulation methods:
  */
 
-static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
+static inline __maybe_unused u64 max_vruntime(u64 max_vruntime, u64 vruntime)
 {
 	s64 delta = (s64)(vruntime - max_vruntime);
 	if (delta > 0)
@@ -532,7 +532,7 @@ static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
 	return max_vruntime;
 }
 
-static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
+static inline __maybe_unused u64 min_vruntime(u64 min_vruntime, u64 vruntime)
 {
 	s64 delta = (s64)(vruntime - min_vruntime);
 	if (delta < 0)
@@ -5547,7 +5547,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
 #ifdef CONFIG_JUMP_LABEL
 static struct static_key __cfs_bandwidth_used;
 
-static inline bool cfs_bandwidth_used(void)
+static inline __maybe_unused bool cfs_bandwidth_used(void)
 {
 	return static_key_false(&__cfs_bandwidth_used);
 }
@@ -5562,7 +5562,7 @@ void cfs_bandwidth_usage_dec(void)
 	static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
 }
 #else /* CONFIG_JUMP_LABEL */
-static bool cfs_bandwidth_used(void)
+static inline __maybe_unused bool cfs_bandwidth_used(void)
 {
 	return true;
 }
@@ -6577,7 +6577,7 @@ static void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p)
 
 #else /* CONFIG_CFS_BANDWIDTH */
 
-static inline bool cfs_bandwidth_used(void)
+static inline __maybe_unused bool cfs_bandwidth_used(void)
 {
 	return false;
 }
-- 
2.43.0.rc1.1336.g36b5255a03ac