1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index a8b31b0ca57f..cf7f2f0e4ef5 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -123,10 +123,10 @@ struct menu_device {
         int             needs_update;
 
         unsigned int    expected_us;
-        u64             predicted_us;
+        unsigned int    predicted_us;
         unsigned int    exit_us;
         unsigned int    bucket;
-        u64             correction_factor[BUCKETS];
+        unsigned int    correction_factor[BUCKETS];
         unsigned int    intervals[INTERVALS];
         int             interval_ptr;
 };
@@ -321,8 +321,13 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
         if (data->correction_factor[data->bucket] == 0)
                 data->correction_factor[data->bucket] = RESOLUTION * DECAY;
 
-        /* Make sure to round up for half microseconds */
-        data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket],
+        /*
+         * Force the result of multiplication to be 64 bits even if both
+         * operands are 32 bits.
+         * Make sure to round up for half microseconds.
+         */
+        data->predicted_us = div_round64((uint64_t)data->expected_us *
+                                         data->correction_factor[data->bucket],
                                          RESOLUTION * DECAY);
 
         get_typical_interval(data);
@@ -388,7 +393,7 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
         unsigned int last_idle_us = cpuidle_get_last_residency(dev);
         struct cpuidle_state *target = &drv->states[last_idx];
         unsigned int measured_us;
-        u64 new_factor;
+        unsigned int new_factor;
 
         /*
          * Ugh, this idle state doesn't support residency measurements, so we
@@ -409,10 +414,9 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
                 measured_us -= data->exit_us;
 
 
-        /* update our correction ratio */
-
-        new_factor = data->correction_factor[data->bucket]
-                        * (DECAY - 1) / DECAY;
+        /* Update our correction ratio */
+        new_factor = data->correction_factor[data->bucket];
+        new_factor -= new_factor / DECAY;
 
         if (data->expected_us > 0 && measured_us < MAX_INTERESTING)
                 new_factor += RESOLUTION * measured_us / data->expected_us;
@@ -425,9 +429,11 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 
         /*
          * We don't want 0 as factor; we always want at least
-         * a tiny bit of estimated time.
+         * a tiny bit of estimated time. Fortunately, due to rounding,
+         * new_factor will stay nonzero regardless of measured_us values
+         * and the compiler can eliminate this test as long as DECAY > 1.
          */
-        if (new_factor == 0)
+        if (DECAY == 1 && unlikely(new_factor == 0))
                 new_factor = 1;
 
         data->correction_factor[data->bucket] = new_factor;