linux-kernel - [PATCH 14/19] timekeeping: Consolidate timekeeping helpers

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Date: Fri,  8 Mar 2024 15:15:07 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...nel.org>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	John Stultz <jstultz@...gle.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Arnd Bergmann <arnd@...db.de>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	linux-s390@...r.kernel.org
Subject: [PATCH 14/19] timekeeping: Consolidate timekeeping helpers

Consolidate timekeeping helpers, making use of timekeeping_cycles_to_ns()
in preference to directly using timekeeping_delta_to_ns().

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 kernel/time/timekeeping.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 618328cd4bc4..1bbfe1ff8d24 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -237,7 +237,9 @@ static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
 	}
 }
 
-static inline u64 timekeeping_debug_get_delta(const struct tk_read_base *tkr)
+static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles);
+
+static inline u64 timekeeping_debug_get_ns(const struct tk_read_base *tkr)
 {
 	struct timekeeper *tk = &tk_core.timekeeper;
 	u64 now, last, mask, max, delta;
@@ -266,22 +268,22 @@ static inline u64 timekeeping_debug_get_delta(const struct tk_read_base *tkr)
 	 */
 	if (unlikely((~delta & mask) < (mask >> 3))) {
 		tk->underflow_seen = 1;
-		delta = 0;
+		now = last;
 	}
 
 	/* Cap delta value to the max_cycles values to avoid mult overflows */
 	if (unlikely(delta > max)) {
 		tk->overflow_seen = 1;
-		delta = tkr->clock->max_cycles;
+		now = last + max;
 	}
 
-	return delta;
+	return timekeeping_cycles_to_ns(tkr, now);
 }
 #else
 static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
 {
 }
-static inline u64 timekeeping_debug_get_delta(const struct tk_read_base *tkr)
+static inline u64 timekeeping_debug_get_ns(const struct tk_read_base *tkr)
 {
 	BUG();
 }
@@ -389,7 +391,7 @@ static __always_inline u64 __timekeeping_get_ns(const struct tk_read_base *tkr)
 static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
 {
 	if (IS_ENABLED(CONFIG_DEBUG_TIMEKEEPING))
-		return timekeeping_delta_to_ns(tkr, timekeeping_debug_get_delta(tkr));
+		return timekeeping_debug_get_ns(tkr);
 
 	return __timekeeping_get_ns(tkr);
 }
-- 
2.34.1