[PATCH 3.18 66/68] e1000e: fix call to do_div() to use u64 arg

Greg Kroah-Hartman
2017-05-05T18:43:25Z

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

commit 30544af5483755b11bb5924736e9e0b45ef0644a upstream.

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>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/ethernet/intel/e1000e/ich8lan.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -983,7 +983,7 @@ static s32 e1000_platform_pm_pch_lpt(str
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) {
@@ -1010,12 +1010,13 @@ static s32 e1000_platform_pm_pch_lpt(str
*/
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));