cpufreq: Initialise default governor before use

When the cpufreq driver starts up at boot time, it calls into the default
governor which might not be initialised yet.  This hurts when the
governor's worker function relies on memory that is not yet set up by its
init function.

This migrates all governors from module_init() to fs_initcall() when being
the default, as was already done in cpufreq_performance when it was the
only possible choice.  The performance governor is always initialized early
because it might be used as fallback even when not being the default.

Fixes at least one actual oops where ondemand is the default governor and
cpufreq_governor_dbs() uses the uninitialised kondemand_wq work-queue
during boot-time.

Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 1bba99747f5b..5d3a04ba6ad2 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -603,5 +603,9 @@ MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
 		"optimised for use in a battery environment");
 MODULE_LICENSE ("GPL");
 
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
+fs_initcall(cpufreq_gov_dbs_init);
+#else
 module_init(cpufreq_gov_dbs_init);
+#endif
 module_exit(cpufreq_gov_dbs_exit);