linux-kernel - [GIT PULL] x86/timers updates for v5.2

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Message-ID: <20190506105212.GA45768@gmail.com>
Date:   Mon, 6 May 2019 12:52:12 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] x86/timers updates for v5.2

Linus,

Please pull the latest x86-timers-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-timers-for-linus

   # HEAD: 81423c37415fe45057d64196ae0ce8e17a9c7148 x86/timer: Don't inline __const_udelay()

Two changes: an LTO improvement, plus the new 'nowatchdog' boot option to 
disable the clocksource watchdog.

 Thanks,

	Ingo

------------------>
Andi Kleen (1):
      x86/timer: Don't inline __const_udelay()

Juri Lelli (1):
      x86/tsc: Add option to disable tsc clocksource watchdog


 Documentation/admin-guide/kernel-parameters.txt | 4 ++++
 arch/x86/kernel/tsc.c                           | 5 ++++-
 arch/x86/lib/delay.c                            | 2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2b8ee90bb644..c4d830003b21 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4703,6 +4703,10 @@
 			[x86] unstable: mark the TSC clocksource as unstable, this
 			marks the TSC unconditionally unstable at bootup and
 			avoids any further wobbles once the TSC watchdog notices.
+			[x86] nowatchdog: disable clocksource watchdog. Used
+			in situations with strict latency requirements (where
+			interruptions from clocksource watchdog are not
+			acceptable).
 
 	turbografx.map[2|3]=	[HW,JOY]
 			TurboGraFX parallel port interface
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 3fae23834069..aab0c82e0a0d 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -283,6 +283,7 @@ int __init notsc_setup(char *str)
 __setup("notsc", notsc_setup);
 
 static int no_sched_irq_time;
+static int no_tsc_watchdog;
 
 static int __init tsc_setup(char *str)
 {
@@ -292,6 +293,8 @@ static int __init tsc_setup(char *str)
 		no_sched_irq_time = 1;
 	if (!strcmp(str, "unstable"))
 		mark_tsc_unstable("boot parameter");
+	if (!strcmp(str, "nowatchdog"))
+		no_tsc_watchdog = 1;
 	return 1;
 }
 
@@ -1349,7 +1352,7 @@ static int __init init_tsc_clocksource(void)
 	if (tsc_unstable)
 		goto unreg;
 
-	if (tsc_clocksource_reliable)
+	if (tsc_clocksource_reliable || no_tsc_watchdog)
 		clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
 
 	if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC_S3))
diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index f5b7f1b3b6d7..b7375dc6898f 100644
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -162,7 +162,7 @@ void __delay(unsigned long loops)
 }
 EXPORT_SYMBOL(__delay);
 
-void __const_udelay(unsigned long xloops)
+noinline void __const_udelay(unsigned long xloops)
 {
 	unsigned long lpj = this_cpu_read(cpu_info.loops_per_jiffy) ? : loops_per_jiffy;
 	int d0;