Thermal: thermal zone governor fix

Commit Message

Zhang, Rui March 3, 2014, 5:46 a.m. UTC

From 635a1f41a8f95a35d1bf24c9cc018ffb018a93e6 Mon Sep 17 00:00:00 2001
From: Zhang Rui <[e-mail]>
Date: Fri, 24 Jan 2014 10:23:19 +0800
Subject: [PATCH] Thermal: thermal zone governor fix

This patch does a cleanup about the thermal zone govenor,
setting and make the following rule.
1. For thermal zone devices that are registered w/o tz->tzp,
   they can use the default thermal governor only.
2. For thermal zone devices w/ governor name specified in
   tz->tzp->governor_name, we will use the default govenor
   if the governor specified is not available at the moment,
   and update tz->governor when the matched governor is registered.

Signed-off-by: Zhang Rui <[e-mail]>
---
 drivers/thermal/thermal_core.c |   25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

Comments

Javi Merino March 3, 2014, 10 a.m. UTC | #1

Hi Rui,

On Mon, Mar 03, 2014 at 05:46:13AM +0000, Zhang Rui wrote:
> From 635a1f41a8f95a35d1bf24c9cc018ffb018a93e6 Mon Sep 17 00:00:00 2001
> From: Zhang Rui <[e-mail]>
> Date: Fri, 24 Jan 2014 10:23:19 +0800
> Subject: [PATCH] Thermal: thermal zone governor fix
> 
> This patch does a cleanup about the thermal zone govenor,
> setting and make the following rule.
> 1. For thermal zone devices that are registered w/o tz->tzp,
>    they can use the default thermal governor only.
> 2. For thermal zone devices w/ governor name specified in
>    tz->tzp->governor_name, we will use the default govenor
>    if the governor specified is not available at the moment,
>    and update tz->governor when the matched governor is registered.
> 
> Signed-off-by: Zhang Rui <[e-mail]>

This solves my issue.  You can add my Acked-by.

I was a bit worried about dereferencing def_governor in
handle_non_critical_trips() without checking if it's initialised.  I
guess that all the thermal zones initialise in device_initcall or
later so by the time they run thermal_zone_device_update(),
thermal_register_governors() must have initialised the default
governor.  So it's not an issue.

Thanks,
Javi

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Patch

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 338a88b..1346205 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -56,10 +56,15 @@  static LIST_HEAD(thermal_governor_list);
 static DEFINE_MUTEX(thermal_list_lock);
 static DEFINE_MUTEX(thermal_governor_lock);
 
+static struct thermal_governor *def_governor;
+
 static struct thermal_governor *__find_governor(const char *name)
 {
 	struct thermal_governor *pos;
 
+	if (!name || !name[0])
+		return def_governor;
+
 	list_for_each_entry(pos, &thermal_governor_list, governor_list)
 		if (!strnicmp(name, pos->name, THERMAL_NAME_LENGTH))
 			return pos;
@@ -82,17 +87,23 @@  int thermal_register_governor(struct thermal_governor *governor)
 	if (__find_governor(governor->name) == NULL) {
 		err = 0;
 		list_add(&governor->governor_list, &thermal_governor_list);
+		if (!def_governor && !strncmp(governor->name,
+			DEFAULT_THERMAL_GOVERNOR, THERMAL_NAME_LENGTH))
+			def_governor = governor;
 	}
 
 	mutex_lock(&thermal_list_lock);
 
 	list_for_each_entry(pos, &thermal_tz_list, node) {
+		/*
+		 * only thermal zones with specified tz->tzp->governor_name
+		 * may run with tz->govenor unset
+		 */
 		if (pos->governor)
 			continue;
-		if (pos->tzp)
-			name = pos->tzp->governor_name;
-		else
-			name = DEFAULT_THERMAL_GOVERNOR;
+
+		name = pos->tzp->governor_name;
+
 		if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH))
 			pos->governor = governor;
 	}
@@ -342,8 +353,8 @@  static void monitor_thermal_zone(struct thermal_zone_device *tz)
 static void handle_non_critical_trips(struct thermal_zone_device *tz,
 			int trip, enum thermal_trip_type trip_type)
 {
-	if (tz->governor)
-		tz->governor->throttle(tz, trip);
+	tz->governor ? tz->governor->throttle(tz, trip) :
+		       def_governor->throttle(tz, trip);
 }
 
 static void handle_critical_trips(struct thermal_zone_device *tz,
@@ -1533,7 +1544,7 @@  struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	if (tz->tzp)
 		tz->governor = __find_governor(tz->tzp->governor_name);
 	else
-		tz->governor = __find_governor(DEFAULT_THERMAL_GOVERNOR);
+		tz->governor = def_governor;
 
 	mutex_unlock(&thermal_governor_lock);