From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, diego.viola@gmail.com,
len.brown@intel.com, rjw@rjwysocki.net, rui.zhang@intel.com
Subject: Re: [PATCH 2/5] clocksource: Allow clocksource_mark_unstable() on unregisered clocksources
Date: Mon, 23 Apr 2018 18:43:25 +0200 [thread overview]
Message-ID: <20180423164325.GR4129@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180423164113.GN4082@hirez.programming.kicks-ass.net>
On Mon, Apr 23, 2018 at 06:41:13PM +0200, Peter Zijlstra wrote:
> I've no idea why it says it cannot do that with the lock held. But
> there's more stale comments in there.
Like that one, the x86 tsc code is the only caller of this. I could not
find anything hotplug.
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -173,10 +173,8 @@ static void __clocksource_unstable(struc
* clocksource_mark_unstable - mark clocksource unstable via watchdog
* @cs: clocksource to be marked unstable
*
- * This function is called instead of clocksource_change_rating from
- * cpu hotplug code to avoid a deadlock between the clocksource mutex
- * and the cpu hotplug mutex. It defers the update of the clocksource
- * to the watchdog thread.
+ * This function is called by the x86 TSC code to mark clocksources as unstable;
+ * it defers demotion and re-selection to a kthread.
*/
void clocksource_mark_unstable(struct clocksource *cs)
{
next prev parent reply other threads:[~2018-04-23 16:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-23 16:16 [PATCH 0/5] Various tsc/clocksource fixes Peter Zijlstra
2018-04-23 16:16 ` [PATCH 1/5] x86,tsc: Always unregister clocksource_tsc_early Peter Zijlstra
2018-04-23 16:16 ` [PATCH 2/5] clocksource: Allow clocksource_mark_unstable() on unregisered clocksources Peter Zijlstra
2018-04-23 16:41 ` Peter Zijlstra
2018-04-23 16:43 ` Peter Zijlstra [this message]
2018-04-23 16:16 ` [PATCH 3/5] clocksource: Initialize cs->wd_list Peter Zijlstra
2018-04-23 16:16 ` [PATCH 4/5] x86,tsc: Fix mark_tsc_unstable() Peter Zijlstra
2018-04-23 16:16 ` [PATCH 5/5] clocksource: Consistent de-rate when marking unstable Peter Zijlstra
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