Commit e05b2efb authored by john stultz's avatar john stultz Committed by Thomas Gleixner

clocksource: Install completely before selecting

Christian Hoffmann reported that the command line clocksource override
with acpi_pm timer fails:

 Kernel command line: <SNIP> clocksource=acpi_pm
 hpet clockevent registered
 Switching to clocksource hpet
 Override clocksource acpi_pm is not HRT compatible.
 Cannot switch while in HRT/NOHZ mode.

The watchdog code is what enables CLOCK_SOURCE_VALID_FOR_HRES, but we
actually end up selecting the clocksource before we enqueue it into
the watchdog list, so that's why we see the warning and fail to switch
to acpi_pm timer as requested. That's particularly bad when we want to
debug timekeeping related problems in early boot.

Put the selection call last.
Reported-by: default avatarChristian Hoffmann <email@christianhoffmann.info>
Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Cc: stable@kernel.org # 32...
Link: http://lkml.kernel.org/r/%3C1304558210.2943.24.camel%40work-vm%3ESigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5895198c
...@@ -685,8 +685,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) ...@@ -685,8 +685,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
/* Add clocksource to the clcoksource list */ /* Add clocksource to the clcoksource list */
mutex_lock(&clocksource_mutex); mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs); clocksource_enqueue(cs);
clocksource_select();
clocksource_enqueue_watchdog(cs); clocksource_enqueue_watchdog(cs);
clocksource_select();
mutex_unlock(&clocksource_mutex); mutex_unlock(&clocksource_mutex);
return 0; return 0;
} }
...@@ -706,8 +706,8 @@ int clocksource_register(struct clocksource *cs) ...@@ -706,8 +706,8 @@ int clocksource_register(struct clocksource *cs)
mutex_lock(&clocksource_mutex); mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs); clocksource_enqueue(cs);
clocksource_select();
clocksource_enqueue_watchdog(cs); clocksource_enqueue_watchdog(cs);
clocksource_select();
mutex_unlock(&clocksource_mutex); mutex_unlock(&clocksource_mutex);
return 0; return 0;
} }
......
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