netdev - [PATCH v2 05/25] timekeeping: Simplify code in timekeeping

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Message-Id: <20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-5-554456a44a15@linutronix.de>
Date: Wed, 09 Oct 2024 10:28:58 +0200
From: Anna-Maria Behnsen <anna-maria@...utronix.de>
To: John Stultz <jstultz@...gle.com>, 
 Frederic Weisbecker <frederic@...nel.org>, 
 Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
 Miroslav Lichvar <mlichvar@...hat.com>, 
 Richard Cochran <richardcochran@...il.com>, 
 Christopher S Hall <christopher.s.hall@...el.com>, 
 Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [PATCH v2 05/25] timekeeping: Simplify code in
 timekeeping_advance()

From: Thomas Gleixner <tglx@...utronix.de>

From: Thomas Gleixner <tglx@...utronix.de>

timekeeping_advance() takes the timekeeper_lock and releases it before
returning. When an early return is required, goto statements are used to
make sure the lock is realeased properly. When the code was written the
locking guard() was not yet available.

Use the guard() to simplify the code and while at it cleanup ordering of
function variables. No functional change.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
---
 kernel/time/timekeeping.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0ae35a71f8cc..e747e46a1a2d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2276,23 +2276,22 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
 {
 	struct timekeeper *real_tk = &tk_core.timekeeper;
 	struct timekeeper *tk = &shadow_timekeeper;
-	u64 offset;
-	int shift = 0, maxshift;
 	unsigned int clock_set = 0;
-	unsigned long flags;
+	int shift = 0, maxshift;
+	u64 offset;
 
-	raw_spin_lock_irqsave(&timekeeper_lock, flags);
+	guard(raw_spinlock_irqsave)(&timekeeper_lock);
 
 	/* Make sure we're fully resumed: */
 	if (unlikely(timekeeping_suspended))
-		goto out;
+		return false;
 
 	offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
 				   tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
 
 	/* Check if there's really nothing to do */
 	if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
-		goto out;
+		return false;
 
 	/* Do some additional sanity checking */
 	timekeeping_check_update(tk, offset);
@@ -2311,8 +2310,7 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
 	maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
 	shift = min(shift, maxshift);
 	while (offset >= tk->cycle_interval) {
-		offset = logarithmic_accumulation(tk, offset, shift,
-							&clock_set);
+		offset = logarithmic_accumulation(tk, offset, shift, &clock_set);
 		if (offset < tk->cycle_interval<<shift)
 			shift--;
 	}
@@ -2341,8 +2339,6 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
 	memcpy(real_tk, tk, sizeof(*tk));
 	/* The memcpy must come last. Do not put anything here! */
 	write_seqcount_end(&tk_core.seq);
-out:
-	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
 	return !!clock_set;
 }

-- 
2.39.5