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From: "Paul E. McKenney" <paulmck@kernel.org>
To: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	John Stultz <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Feng Tang <feng.tang@intel.com>, Waiman Long <longman@redhat.com>,
	Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>,
	x86@kernel.org, kernel-team@meta.com,
	linux-kernel@vger.kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH v2 TSC and clocksource-watchdog updates for v6.12 3/5]  clocksource: Fix comments on WATCHDOG_THRESHOLD & WATCHDOG_MAX_SKEW
Date: Fri,  2 Aug 2024 08:46:16 -0700	[thread overview]
Message-ID: <20240802154618.4149953-3-paulmck@kernel.org> (raw)
In-Reply-To: <dac058b2-68c7-4b9a-a428-afb2b4b03ea0@paulmck-laptop>

The WATCHDOG_THRESHOLD macro is no longer used to supply a default value
for ->uncertainty_margin, but WATCHDOG_MAX_SKEW now is.  Therefore,
update the comments to reflect this change.

Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
---
 kernel/time/clocksource.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 581cdbb538448..ee0ad5e4d5170 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -113,7 +113,6 @@ static u64 suspend_start;
 
 /*
  * Threshold: 0.0312s, when doubled: 0.0625s.
- * Also a default for cs->uncertainty_margin when registering clocks.
  */
 #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 5)
 
@@ -139,6 +138,13 @@ static u64 suspend_start;
 #define MAX_SKEW_USEC	(125 * WATCHDOG_INTERVAL / HZ)
 #endif
 
+/*
+ * Default for maximum permissible skew when cs->uncertainty_margin is
+ * not specified, and the lower bound even when cs->uncertainty_margin
+ * is specified.  This is also the default that is used when registering
+ * clocks with unspecifed cs->uncertainty_margin, so this macro is used
+ * even in CONFIG_CLOCKSOURCE_WATCHDOG=n kernels.
+ */
 #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC)
 
 #ifdef CONFIG_CLOCKSOURCE_WATCHDOG
-- 
2.40.1


  parent reply	other threads:[~2024-08-02 15:46 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <463c0174-356b-4918-8759-c36b1b30ba55@paulmck-laptop>
2024-08-02 15:45 ` [PATCH v2 clocksource 0/5] TSC and clocksource-watchdog updates for v6.12 Paul E. McKenney
2024-08-02 15:46   ` [PATCH v2 TSC and clocksource-watchdog updates for v6.12 1/5] clocksource: Improve comments for watchdog skew bounds Paul E. McKenney
2024-08-02 16:43     ` [tip: timers/clocksource] " tip-bot2 for Borislav Petkov
2024-08-02 15:46   ` [PATCH v2 TSC and clocksource-watchdog updates for v6.12 2/5] clocksource: Fix brown-bag boolean thinko in cs_watchdog_read() Paul E. McKenney
2024-08-02 16:34     ` [tip: timers/urgent] " tip-bot2 for Paul E. McKenney
2024-08-02 15:46   ` Paul E. McKenney [this message]
2024-08-02 16:43     ` [tip: timers/clocksource] clocksource: Fix comments on WATCHDOG_THRESHOLD & WATCHDOG_MAX_SKEW tip-bot2 for Paul E. McKenney
2024-08-02 15:46   ` [PATCH v2 TSC and clocksource-watchdog updates for v6.12 4/5] clocksource: Set cs_watchdog_read() checks based on .uncertainty_margin Paul E. McKenney
2024-08-02 16:43     ` [tip: timers/clocksource] " tip-bot2 for Paul E. McKenney
2024-08-02 15:46   ` [PATCH v2 TSC and clocksource-watchdog updates for v6.12 5/5] tsc: Check for sockets instead of CPUs to make code match comment Paul E. McKenney
2024-08-02 16:43     ` [tip: x86/timers] x86/tsc: " tip-bot2 for Paul E. McKenney

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