PM / devfreq: Rework freq_table to be local to devfreq struct

On a devfreq PROBE_DEFER, the freq_table in the driver profile struct,
is never reset and may be leaved in an undefined state.

This comes from the fact that we store the freq_table in the driver
profile struct that is commonly defined as static and not reset on
PROBE_DEFER.
We currently skip the reinit of the freq_table if we found
it's already defined since a driver may declare his own freq_table.

This logic is flawed in the case devfreq core generate a freq_table, set
it in the profile struct and then PROBE_DEFER, freeing the freq_table.
In this case devfreq will found a NOT NULL freq_table that has been
freed, skip the freq_table generation and probe the driver based on the
wrong table.

To fix this and correctly handle PROBE_DEFER, use a local freq_table and
max_state in the devfreq struct and never modify the freq_table present
in the profile struct if it does provide it.

Fixes: 0ec09ac2cebe ("PM / devfreq: Set the freq_table of devfreq device")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index dc10bee75a72..34aab4dd336c 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -148,6 +148,8 @@ struct devfreq_stats {
  *		reevaluate operable frequencies. Devfreq users may use
  *		devfreq.nb to the corresponding register notifier call chain.
  * @work:	delayed work for load monitoring.
+ * @freq_table:		current frequency table used by the devfreq driver.
+ * @max_state:		count of entry present in the frequency table.
  * @previous_freq:	previously configured frequency value.
  * @last_status:	devfreq user device info, performance statistics
  * @data:	Private data of the governor. The devfreq framework does not
@@ -185,6 +187,9 @@ struct devfreq {
 	struct notifier_block nb;
 	struct delayed_work work;
 
+	unsigned long *freq_table;
+	unsigned int max_state;
+
 	unsigned long previous_freq;
 	struct devfreq_dev_status last_status;