linux-kernel - [tip: timers/core] timekeeping: Encapsulate locking/unlocking of timekeeper

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Message-ID: <172987928529.1442.17064746701978445916.tip-bot2@tip-bot2>
Date: Fri, 25 Oct 2024 18:01:25 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
 "Anna-Maria Behnsen" <anna-maria@...utronix.de>,
 John Stultz <jstultz@...gle.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] timekeeping: Encapsulate locking/unlocking of
 timekeeper_lock

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

Commit-ID:     dbdcf8c4caeca8192daa43429ccf23a1feec126c
Gitweb:        https://git.kernel.org/tip/dbdcf8c4caeca8192daa43429ccf23a1feec126c
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Wed, 09 Oct 2024 10:29:01 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Fri, 25 Oct 2024 19:49:13 +02:00

timekeeping: Encapsulate locking/unlocking of timekeeper_lock

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 <tglx@...utronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: John Stultz <jstultz@...gle.com>
Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-8-554456a44a15@linutronix.de

---
 kernel/time/timekeeping.c          | 15 ++++++++++++++-
 kernel/time/timekeeping_internal.h |  3 ++-
 kernel/time/vsyscall.c             |  5 ++---
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 848d2b1..77e0a0f 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);
+}
+
 /*
  * Multigrain timestamps require tracking the latest fine-grained timestamp
  * that has been issued, and never returning a coarse-grained timestamp that is
diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h
index 0bbae82..b3dca83 100644
--- a/kernel/time/timekeeping_internal.h
+++ b/kernel/time/timekeeping_internal.h
@@ -49,6 +49,7 @@ 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 9193d61..98488b2 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);
 }