[PATCH 3.14 023/125] thermal: step_wise: fix: Prevent from binary overflow when trend is dropping

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3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lukasz Majewski <l.majewski@xxxxxxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
Cc: Mason <slash.tmp@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/thermal/step_wise.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/thermal/step_wise.c
+++ b/drivers/thermal/step_wise.c
@@ -76,7 +76,7 @@ static unsigned long get_target_state(st
 			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 {


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