re: thermal: introduce the Power Allocator governor

re: thermal: introduce the Power Allocator governor

[Dan Carpenter]

Hello Javi Merino,

The patch 6b775e870c56: "thermal: introduce the Power Allocator
governor" from Mar 2, 2015, leads to the following static checker
warning:

	drivers/thermal/power_allocator.c:304 divvy_up_power()
	warn: should 'req_power[i] * power_range' be a 64 bit type?

drivers/thermal/power_allocator.c
   288  static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
   289                             u32 total_req_power, u32 power_range,
   290                             u32 *granted_power, u32 *extra_actor_power)
   291  {
   292          u32 extra_power, capped_extra_power;
   293          int i;
   294  
   295          /*
   296           * Prevent division by 0 if none of the actors request power.
   297           */
   298          if (!total_req_power)
   299                  total_req_power = 1;
   300  
   301          capped_extra_power = 0;
   302          extra_power = 0;
   303          for (i = 0; i < num_actors; i++) {
   304                  u64 req_range = req_power[i] * power_range;

Both req_power[i] and power_range are u32 so the high bits of req_range
are not used.

   305  
   306                  granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range,
   307                                                           total_req_power);
   308  
   309                  if (granted_power[i] > max_power[i]) {
   310                          extra_power += granted_power[i] - max_power[i];
   311                          granted_power[i] = max_power[i];
   312                  }
   313  
   314                  extra_actor_power[i] = max_power[i] - granted_power[i];
   315                  capped_extra_power += extra_actor_power[i];
   316          }

regards,
dan carpenter

[PATCH] thermal: power_allocator: req_range multiplication should be a 64 bit type

[Javi Merino]

req_range is declared as a u64 to cope with overflows in the
multiplication of two u32.  As both req_power and power_range are u32,
we need to make sure the multiplication is done with u64 types.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/thermal/power_allocator.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
index f0fbea386869..a58ae2e1f3cd 100644
--- a/drivers/thermal/power_allocator.c
+++ b/drivers/thermal/power_allocator.c
@@ -303,7 +303,7 @@ static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
 	capped_extra_power = 0;
 	extra_power = 0;
 	for (i = 0; i < num_actors; i++) {
-		u64 req_range = req_power[i] * power_range;
+		u64 req_range = (u64)req_power[i] * power_range;
 
 		granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range,
 							 total_req_power);
-- 
1.9.1