[PATCH v2 1/7] x86,tsc: Always unregister clocksource_tsc_early

[Peter Zijlstra]

Don't leave the tsc-early clocksource registered if it errors out
early.

This was reported by Diego, who on his Core2 era machine got TSC
invalidated while it was running with tsc-early (due to C-states).
This results in keeping tsc-early with very bad effects.

Reported-and-Tested-by: Diego Viola <diego.viola@xxxxxxxxx>
Fixes: aa83c45762a2 ("x86/tsc: Introduce early tsc clocksource")
Cc: stable@xxxxxxxxxx
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 arch/x86/kernel/tsc.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1244,7 +1244,7 @@ static void tsc_refine_calibration_work(
 
 	/* Don't bother refining TSC on unstable systems */
 	if (tsc_unstable)
-		return;
+		goto unreg;
 
 	/*
 	 * Since the work is started early in boot, we may be
@@ -1297,11 +1297,12 @@ static void tsc_refine_calibration_work(
 
 out:
 	if (tsc_unstable)
-		return;
+		goto unreg;
 
 	if (boot_cpu_has(X86_FEATURE_ART))
 		art_related_clocksource = &clocksource_tsc;
 	clocksource_register_khz(&clocksource_tsc, tsc_khz);
+unreg:
 	clocksource_unregister(&clocksource_tsc_early);
 }
 
@@ -1311,8 +1312,8 @@ static int __init init_tsc_clocksource(v
 	if (!boot_cpu_has(X86_FEATURE_TSC) || tsc_disabled > 0 || !tsc_khz)
 		return 0;
 
-	if (check_tsc_unstable())
-		return 0;
+	if (tsc_unstable)
+		goto unreg;
 
 	if (tsc_clocksource_reliable)
 		clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
@@ -1328,6 +1329,7 @@ static int __init init_tsc_clocksource(v
 		if (boot_cpu_has(X86_FEATURE_ART))
 			art_related_clocksource = &clocksource_tsc;
 		clocksource_register_khz(&clocksource_tsc, tsc_khz);
+unreg:
 		clocksource_unregister(&clocksource_tsc_early);
 		return 0;
 	}