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@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-18-anna-maria@linutronix.de

diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index ccf39befde853db695574d216eabb4d8fc31dbda..7e3090109e33bef46feac22955b1ef6a96fd8da2 100644 (file)
--- 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 4420cdf59e8cac7fc60f092b4c58beb7d5a61543..e02ac46079858cdeaf38417d1b08a65797d447d3 100644 (file)
--- 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,