sched/debug: Change SCHED_WARN_ON() to WARN_ON_ONCE()

The scheduler has this special SCHED_WARN() facility that
depends on CONFIG_SCHED_DEBUG.

Since CONFIG_SCHED_DEBUG is getting removed, convert
SCHED_WARN() to WARN_ON_ONCE().

Note that the warning output isn't 100% equivalent:

   #define SCHED_WARN_ON(x)      WARN_ONCE(x, #x)

Because SCHED_WARN_ON() would output the 'x' condition
as well, while WARN_ONCE() will only show a backtrace.

Hopefully these are rare enough to not really matter.

If it does, we should probably introduce a new WARN_ON()
variant that outputs the condition in stringified form,
or improve WARN_ON() itself.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250317104257.3496611-2-mingo@kernel.org

1 files changed, 5 insertions, 11 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5d853f91004e..fadaabeff994 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -91,12 +91,6 @@ struct cpuidle_state;
 #include "cpupri.h"
 #include "cpudeadline.h"
 
-#ifdef CONFIG_SCHED_DEBUG
-# define SCHED_WARN_ON(x)      WARN_ONCE(x, #x)
-#else
-# define SCHED_WARN_ON(x)      ({ (void)(x), 0; })
-#endif
-
 /* task_struct::on_rq states: */
 #define TASK_ON_RQ_QUEUED	1
 #define TASK_ON_RQ_MIGRATING	2
@@ -1571,7 +1565,7 @@ static inline void update_idle_core(struct rq *rq) { }
 
 static inline struct task_struct *task_of(struct sched_entity *se)
 {
-	SCHED_WARN_ON(!entity_is_task(se));
+	WARN_ON_ONCE(!entity_is_task(se));
 	return container_of(se, struct task_struct, se);
 }
 
@@ -1652,7 +1646,7 @@ static inline void assert_clock_updated(struct rq *rq)
 	 * The only reason for not seeing a clock update since the
 	 * last rq_pin_lock() is if we're currently skipping updates.
 	 */
-	SCHED_WARN_ON(rq->clock_update_flags < RQCF_ACT_SKIP);
+	WARN_ON_ONCE(rq->clock_update_flags < RQCF_ACT_SKIP);
 }
 
 static inline u64 rq_clock(struct rq *rq)
@@ -1699,7 +1693,7 @@ static inline void rq_clock_cancel_skipupdate(struct rq *rq)
 static inline void rq_clock_start_loop_update(struct rq *rq)
 {
 	lockdep_assert_rq_held(rq);
-	SCHED_WARN_ON(rq->clock_update_flags & RQCF_ACT_SKIP);
+	WARN_ON_ONCE(rq->clock_update_flags & RQCF_ACT_SKIP);
 	rq->clock_update_flags |= RQCF_ACT_SKIP;
 }
 
@@ -1774,7 +1768,7 @@ static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf)
 	rq->clock_update_flags &= (RQCF_REQ_SKIP|RQCF_ACT_SKIP);
 	rf->clock_update_flags = 0;
 # ifdef CONFIG_SMP
-	SCHED_WARN_ON(rq->balance_callback && rq->balance_callback != &balance_push_callback);
+	WARN_ON_ONCE(rq->balance_callback && rq->balance_callback != &balance_push_callback);
 # endif
 #endif
 }
@@ -2685,7 +2679,7 @@ static inline void idle_set_state(struct rq *rq,
 
 static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 {
-	SCHED_WARN_ON(!rcu_read_lock_held());
+	WARN_ON_ONCE(!rcu_read_lock_held());
 
 	return rq->idle_state;
 }