linux-kernel - [PATCH 5.15 103/135] Revert "parisc: Mark sched_clock unstable only if clocks are not syncronized"

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Date:   Tue, 10 May 2022 15:08:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Helge Deller <deller@....de>,
        John David Anglin <dave.anglin@...l.net>
Subject: [PATCH 5.15 103/135] Revert "parisc: Mark sched_clock unstable only if clocks are not syncronized"

From: Helge Deller <deller@....de>

commit 7962c0896429af2a0e00ec6bc15d992536453b2d upstream.

This reverts commit d97180ad68bdb7ee10f327205a649bc2f558741d.

It triggers RCU stalls at boot with a 32-bit kernel.

Signed-off-by: Helge Deller <deller@....de>
Noticed-by: John David Anglin <dave.anglin@...l.net>
Cc: stable@...r.kernel.org # v5.15+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/parisc/kernel/setup.c |    2 ++
 arch/parisc/kernel/time.c  |    6 +-----
 2 files changed, 3 insertions(+), 5 deletions(-)

--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -150,6 +150,8 @@ void __init setup_arch(char **cmdline_p)
 #ifdef CONFIG_PA11
 	dma_ops_init();
 #endif
+
+	clear_sched_clock_stable();
 }
 
 /*
--- a/arch/parisc/kernel/time.c
+++ b/arch/parisc/kernel/time.c
@@ -249,13 +249,9 @@ void __init time_init(void)
 static int __init init_cr16_clocksource(void)
 {
 	/*
-	 * The cr16 interval timers are not syncronized across CPUs, even if
-	 * they share the same socket.
+	 * The cr16 interval timers are not synchronized across CPUs.
 	 */
 	if (num_online_cpus() > 1 && !running_on_qemu) {
-		/* mark sched_clock unstable */
-		clear_sched_clock_stable();
-
 		clocksource_cr16.name = "cr16_unstable";
 		clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE;
 		clocksource_cr16.rating = 0;