[Intel-wired-lan] [net-next v2] e1000e: fix call to do_div() to use u64 arg

* [Intel-wired-lan] [net-next v2] e1000e: fix call to do_div() to use u64 arg
@ 2015-04-09 21:45 Jeff Kirsher
  2015-04-09 22:45 ` Alexander Duyck
  0 siblings, 1 reply; 4+ messages in thread
From: Jeff Kirsher @ 2015-04-09 21:45 UTC (permalink / raw)
  To: intel-wired-lan

We were using s64 for lat_ns (latency nano-second value) since in
our calculations a negative value could be a resultant.  For negative
values, we then assign lat_ns to be zero, so the value passed to
do_div() was never negative, but do_div() expects the argument type
to be u64, so do a cast to resolve a compile warning seen on
PowerPC.

CC: Yanjiang Jin <yanjiang.jin@windriver.com>
CC: Yanir Lubetkin <yanirx.lubetkin@intel.com>
Reported-by: Yanjiang Jin <yanjiang.jin@windriver.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
v2: fixed the patch to not use a cast to resolve the PowerPC compile
    warning
---
 drivers/net/ethernet/intel/e1000e/ich8lan.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index 9d81c03..7053863 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -1015,7 +1015,7 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
 		u16 max_snoop, max_nosnoop;
 		u16 max_ltr_enc;	/* max LTR latency encoded */
 		s64 lat_ns;	/* latency (ns) */
-		s64 value;
+		u64 value;
 		u32 rxa;
 
 		if (!hw->adapter->max_frame_size) {
@@ -1042,12 +1042,13 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
 		 */
 		lat_ns = ((s64)rxa * 1024 -
 			  (2 * (s64)hw->adapter->max_frame_size)) * 8 * 1000;
-		if (lat_ns < 0)
-			lat_ns = 0;
-		else
-			do_div(lat_ns, speed);
+		if (lat_ns < 0) {
+			value = 0;
+		} else {
+			value = lat_ns;
+			do_div(value, speed);
+		}
 
-		value = lat_ns;
 		while (value > PCI_LTR_VALUE_MASK) {
 			scale++;
 			value = DIV_ROUND_UP(value, (1 << 5));


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