The following commit has been merged into the timers/core branch of tip:
Commit-ID: 8e7e247f64a1e0fee430aba28d9108f7598eb237
Gitweb: https://git.kernel.org/tip/8e7e247f64a1e0fee430aba28d9108f7598eb237
Author: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
AuthorDate: Wed, 21 Feb 2024 10:05:33 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 22 Feb 2024 17:52:30 +01:00
timers: Introduce add_timer() variants which modify timer flags
A timer might be used as a pinned timer (using add_timer_on()) and later on
as non-pinned timer using add_timer(). When the "NOHZ timer pull at expiry
model" is in place, the TIMER_PINNED flag is required to be used whenever a
timer needs to expire on a dedicated CPU. Otherwise the flag must not be
set if expiration on a dedicated CPU is not required.
add_timer_on()'s behavior will be changed during the preparation patches
for the "NOHZ timer pull at expiry model" to unconditionally set the
TIMER_PINNED flag. To be able to clear/ set the flag when queueing a
timer, two variants of add_timer() are introduced.
This is a preparatory step and has 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/20240221090548.36600-6-anna-maria@xxxxxxxxxxxxx
---
include/linux/timer.h | 2 ++
kernel/time/timer.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+)
diff --git a/include/linux/timer.h b/include/linux/timer.h
index f18a2f1..2be8be6 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -165,6 +165,8 @@ extern int timer_reduce(struct timer_list *timer, unsigned long expires);
#define NEXT_TIMER_MAX_DELTA ((1UL << 30) - 1)
extern void add_timer(struct timer_list *timer);
+extern void add_timer_local(struct timer_list *timer);
+extern void add_timer_global(struct timer_list *timer);
extern int try_to_del_timer_sync(struct timer_list *timer);
extern int timer_delete_sync(struct timer_list *timer);
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 74cfe21..bef8cb8 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1291,6 +1291,40 @@ void add_timer(struct timer_list *timer)
EXPORT_SYMBOL(add_timer);
/**
+ * add_timer_local() - Start a timer on the local CPU
+ * @timer: The timer to be started
+ *
+ * Same as add_timer() except that the timer flag TIMER_PINNED is set.
+ *
+ * See add_timer() for further details.
+ */
+void add_timer_local(struct timer_list *timer)
+{
+ if (WARN_ON_ONCE(timer_pending(timer)))
+ return;
+ timer->flags |= TIMER_PINNED;
+ __mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING);
+}
+EXPORT_SYMBOL(add_timer_local);
+
+/**
+ * add_timer_global() - Start a timer without TIMER_PINNED flag set
+ * @timer: The timer to be started
+ *
+ * Same as add_timer() except that the timer flag TIMER_PINNED is unset.
+ *
+ * See add_timer() for further details.
+ */
+void add_timer_global(struct timer_list *timer)
+{
+ if (WARN_ON_ONCE(timer_pending(timer)))
+ return;
+ timer->flags &= ~TIMER_PINNED;
+ __mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING);
+}
+EXPORT_SYMBOL(add_timer_global);
+
+/**
* add_timer_on - Start a timer on a particular CPU
* @timer: The timer to be started
* @cpu: The CPU to start it on
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