[3.16.y-ckt stable] Patch "thermal: step_wise: fix: Prevent from binary overflow when trend is dropping" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    thermal: step_wise: fix: Prevent from binary overflow when trend is dropping

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 072cb4b109eb85c32fcf0f8073fe280fec777f7c Mon Sep 17 00:00:00 2001
From: Lukasz Majewski <l.majewski at samsung.com>
Date: Wed, 24 Sep 2014 10:27:10 +0200
Subject: thermal: step_wise: fix: Prevent from binary overflow when trend is
 dropping

commit 26bb0e9a1a938ec98ee07aa76533f1a711fba706 upstream.

It turns out that some boards can have instance->lower greater than 0 and
when thermal trend is dropping it results with next_target equal to -1.

Since the next_target is defined as unsigned long it is interpreted as
0xFFFFFFFF and larger than instance->upper.
As a result the next_target is set to instance->upper which ramps up to
maximal cooling device target when the temperature is steadily decreasing.

Signed-off-by: Lukasz Majewski <l.majewski at samsung.com>
Signed-off-by: Zhang Rui <rui.zhang at intel.com>
Cc: Mason <slash.tmp at free.fr>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/thermal/step_wise.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
index ee52ab7d3730..c501eba601da 100644
--- a/drivers/thermal/step_wise.c
+++ b/drivers/thermal/step_wise.c
@@ -76,7 +76,7 @@ static unsigned long get_target_state(struct thermal_instance *instance,
 			next_target = instance->upper;
 		break;
 	case THERMAL_TREND_DROPPING:
-		if (cur_state == instance->lower) {
+		if (cur_state <= instance->lower) {
 			if (!throttle)
 				next_target = THERMAL_NO_TARGET;
 		} else {