drivers/cpuidle/governors/menu.c: fix undefined reference to `__udivdi3'
Stephen Hemminger [Fri, 8 Jan 2010 22:43:08 +0000 (14:43 -0800)]
menu: use proper 64 bit math

The new menu governor is incorrectly doing a 64 bit divide.  Compile
tested only

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/cpuidle/governors/menu.c

index 6810443..73655ae 100644 (file)
@@ -18,6 +18,7 @@
 #include <linux/hrtimer.h>
 #include <linux/tick.h>
 #include <linux/sched.h>
+#include <linux/math64.h>
 
 #define BUCKETS 12
 #define RESOLUTION 1024
@@ -169,6 +170,12 @@ static DEFINE_PER_CPU(struct menu_device, menu_devices);
 
 static void menu_update(struct cpuidle_device *dev);
 
+/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
+static u64 div_round64(u64 dividend, u32 divisor)
+{
+       return div_u64(dividend + (divisor / 2), divisor);
+}
+
 /**
  * menu_select - selects the next idle state to enter
  * @dev: the CPU
@@ -209,9 +216,8 @@ static int menu_select(struct cpuidle_device *dev)
                data->correction_factor[data->bucket] = RESOLUTION * DECAY;
 
        /* Make sure to round up for half microseconds */
-       data->predicted_us = DIV_ROUND_CLOSEST(
-               data->expected_us * data->correction_factor[data->bucket],
-               RESOLUTION * DECAY);
+       data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket],
+                                        RESOLUTION * DECAY);
 
        /*
         * We want to default to C1 (hlt), not to busy polling