[tip: sched/hrtick] hrtimer: Optimize for_each_active_base()

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the sched/hrtick branch of tip:

Commit-ID:     3601a1d85028d7d479e1571419174fc3334f58f5
Gitweb:        https://git.kernel.org/tip/3601a1d85028d7d479e1571419174fc3334f58f5
Author:        Thomas Gleixner <tglx@xxxxxxxxxx>
AuthorDate:    Tue, 24 Feb 2026 17:38:42 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 27 Feb 2026 16:40:15 +01:00

hrtimer: Optimize for_each_active_base()

Give the compiler some help to emit way better code.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260224163431.599804894@xxxxxxxxxx
---
 kernel/time/hrtimer.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index b0e7e29..d1e5848 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -529,22 +529,10 @@ static inline void debug_activate(struct hrtimer *timer, enum hrtimer_mode mode,
 	trace_hrtimer_start(timer, mode, was_armed);
 }
 
-static struct hrtimer_clock_base *
-__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
-{
-	unsigned int idx;
-
-	if (!*active)
-		return NULL;
-
-	idx = __ffs(*active);
-	*active &= ~(1U << idx);
-
-	return &cpu_base->clock_base[idx];
-}
-
-#define for_each_active_base(base, cpu_base, active)		\
-	while ((base = __next_base((cpu_base), &(active))))
+#define for_each_active_base(base, cpu_base, active)					\
+	for (unsigned int idx = ffs(active); idx--; idx = ffs((active)))		\
+		for (bool done = false; !done; active &= ~(1U << idx))			\
+			for (base = &cpu_base->clock_base[idx]; !done; done = true)
 
 #if defined(CONFIG_NO_HZ_COMMON)
 /*