[v2,08/25] timekeeping: Encapsulate locking/unlocking of timekeeper_lock

Commit Message

Anna-Maria Behnsen Oct. 9, 2024, 8:29 a.m. UTC

From: Thomas Gleixner <[e-mail]>

From: Thomas Gleixner <[e-mail]>

timekeeper_lock protects updates of timekeeper (tk_core). It is also used
by vdso_update_begin/end() and not only internally by the timekeeper code.

As long as there is only a single timekeeper, this works fine.  But when
the timekeeper infrastructure will be reused for per ptp clock timekeepers,
timekeeper_lock needs to be part of tk_core..

Therefore encapuslate locking/unlocking of timekeeper_lock and make the
lock static.

Signed-off-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Anna-Maria Behnsen <[e-mail]>
---
 kernel/time/timekeeping.c          | 15 ++++++++++++++-
 kernel/time/timekeeping_internal.h |  3 ++-
 kernel/time/vsyscall.c             |  5 ++---
 3 files changed, 18 insertions(+), 5 deletions(-)

Comments

John Stultz Oct. 24, 2024, 9:19 p.m. UTC | #1

On Wed, Oct 9, 2024 at 1:29 AM Anna-Maria Behnsen
<[e-mail]> wrote:
>
> From: Thomas Gleixner <[e-mail]>
>
> From: Thomas Gleixner <[e-mail]>
>
> timekeeper_lock protects updates of timekeeper (tk_core). It is also used
> by vdso_update_begin/end() and not only internally by the timekeeper code.
>
> As long as there is only a single timekeeper, this works fine.  But when
> the timekeeper infrastructure will be reused for per ptp clock timekeepers,
> timekeeper_lock needs to be part of tk_core..
>
> Therefore encapuslate locking/unlocking of timekeeper_lock and make the
> lock static.
>
> Signed-off-by: Thomas Gleixner <[e-mail]>
> Signed-off-by: Anna-Maria Behnsen <[e-mail]>

Acked-by: John Stultz <[e-mail]>

Patch

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 267b28cf2ab0..c69004936b29 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -41,7 +41,7 @@  enum timekeeping_adv_mode {
 	TK_ADV_FREQ
 };
 
-DEFINE_RAW_SPINLOCK(timekeeper_lock);
+static DEFINE_RAW_SPINLOCK(timekeeper_lock);
 
 /*
  * The most important data for readout fits into a single 64 byte
@@ -114,6 +114,19 @@  static struct tk_fast tk_fast_raw  ____cacheline_aligned = {
 	.base[1] = FAST_TK_INIT,
 };
 
+unsigned long timekeeper_lock_irqsave(void)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&timekeeper_lock, flags);
+	return flags;
+}
+
+void timekeeper_unlock_irqrestore(unsigned long flags)
+{
+	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+}
+
 static inline void tk_normalize_xtime(struct timekeeper *tk)
 {
 	while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h
index 4ca2787d1642..3babb2bac579 100644
--- a/kernel/time/timekeeping_internal.h
+++ b/kernel/time/timekeeping_internal.h
@@ -34,6 +34,7 @@  static inline u64 clocksource_delta(u64 now, u64 last, u64 mask)
 #endif
 
 /* Semi public for serialization of non timekeeper VDSO updates. */
-extern raw_spinlock_t timekeeper_lock;
+unsigned long timekeeper_lock_irqsave(void);
+void timekeeper_unlock_irqrestore(unsigned long flags);
 
 #endif /* _TIMEKEEPING_INTERNAL_H */
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index 9193d6133e5d..98488b20b594 100644
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -151,9 +151,8 @@  void update_vsyscall_tz(void)
 unsigned long vdso_update_begin(void)
 {
 	struct vdso_data *vdata = __arch_get_k_vdso_data();
-	unsigned long flags;
+	unsigned long flags = timekeeper_lock_irqsave();
 
-	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 	vdso_write_begin(vdata);
 	return flags;
 }
@@ -172,5 +171,5 @@  void vdso_update_end(unsigned long flags)
 
 	vdso_write_end(vdata);
 	__arch_sync_vdso_data(vdata);
-	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+	timekeeper_unlock_irqrestore(flags);
 }