[tip: timers/core] timers: Introduce function to check timer base is_idle flag

[tip-bot2 for Anna-Maria Behnsen]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     57e95a5c4117dc6a67dc416d82079c02dab7e983
Gitweb:        https://git.kernel.org/tip/57e95a5c4117dc6a67dc416d82079c02dab7e983
Author:        Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
AuthorDate:    Wed, 21 Feb 2024 10:05:45 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 22 Feb 2024 17:52:32 +01:00

timers: Introduce function to check timer base is_idle flag

To prepare for the conversion of the NOHZ timer placement to a pull at
expiry time model it's required to have a function that returns the value
of the is_idle flag of the timer base to keep the hierarchy states during
online in sync with timer base state.

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240221090548.36600-18-anna-maria@xxxxxxxxxxxxx

---
 kernel/time/tick-internal.h |  1 +
 kernel/time/timer.c         | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index ccf39be..7e30901 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -165,6 +165,7 @@ extern void fetch_next_timer_interrupt_remote(unsigned long basej, u64 basem,
 					      unsigned int cpu);
 extern void timer_lock_remote_bases(unsigned int cpu);
 extern void timer_unlock_remote_bases(unsigned int cpu);
+extern bool timer_base_is_idle(void);
 # endif
 #else /* CONFIG_NO_HZ_COMMON */
 static inline void timers_update_nohz(void) { }
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 4420cdf..e02ac46 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -2159,6 +2159,16 @@ void timer_lock_remote_bases(unsigned int cpu)
 	raw_spin_lock(&base_local->lock);
 	raw_spin_lock_nested(&base_global->lock, SINGLE_DEPTH_NESTING);
 }
+
+/**
+ * timer_base_is_idle() - Return whether timer base is set idle
+ *
+ * Returns value of local timer base is_idle value.
+ */
+bool timer_base_is_idle(void)
+{
+	return __this_cpu_read(timer_bases[BASE_LOCAL].is_idle);
+}
 # endif /* CONFIG_SMP */
 
 static inline u64 __get_next_timer_interrupt(unsigned long basej, u64 basem,