[PATCH] cpuidle: teo: fix underflow of recent intercepts

[Christian Loehle]

The recent counter of each cpuidle state bin reflects the number of
recent intercepts. It's decremented and incremented accordingly.
The decrement was never checked for 0, therefore underflowing into a
value teo cannot easily recover from.

The underflow lead to deeper idle states being skipped because teo
assumed interception was likely and it preferring shallower states.

Fixes: 77577558f25d ("cpuidle: teo: Rework most recent idle duration values treatment")
Signed-off-by: Christian Loehle <christian.loehle@xxxxxxx>
---
 drivers/cpuidle/governors/teo.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/governors/teo.c b/drivers/cpuidle/governors/teo.c
index 7244f71c59c5..42fb2771e35d 100644
--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -290,7 +290,8 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 	if (cpu_data->next_recent_idx >= NR_RECENT)
 		cpu_data->next_recent_idx = 0;
 
-	if (cpu_data->recent_idx[i] >= 0)
+	if (cpu_data->recent_idx[i] >= 0 &&
+			cpu_data->state_bins[cpu_data->recent_idx[i]].recent)
 		cpu_data->state_bins[cpu_data->recent_idx[i]].recent--;
 
 	/*
-- 
2.34.1