net/mlx4_en: Fix type mismatch for 32-bit systems

slavashw · davem330 · commit 61b6034c6cfd · 2016-12-29T14:17:40.000-05:00
is_power_of_2 expects unsigned long and we pass u64 max_val_cycles, this will be truncated on 32 bit systems, and the result is not what we were expecting. div_u64 expects u32 as a second argument and we pass max_val_cycles_rounded which is u64 hence it will always be truncated. Fix was tested on both 64 and 32 bit systems and got same results for max_val_cycles and max_val_cycles_rounded. Fixes: 4850cf4 ("net/mlx4_en: Resolve dividing by zero in 32-bit system") Signed-off-by: Slava Shwartsman <slavash@mellanox.com> Signed-off-by: Tariq Toukan <tariqt@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
@@ -245,13 +245,9 @@ static u32 freq_to_shift(u16 freq)
 {
 	u32 freq_khz = freq * 1000;
 	u64 max_val_cycles = freq_khz * 1000 * MLX4_EN_WRAP_AROUND_SEC;
-	u64 tmp_rounded =
-		roundup_pow_of_two(max_val_cycles) > max_val_cycles ?
-		roundup_pow_of_two(max_val_cycles) - 1 : UINT_MAX;
-	u64 max_val_cycles_rounded = is_power_of_2(max_val_cycles + 1) ?
-		max_val_cycles : tmp_rounded;
+	u64 max_val_cycles_rounded = 1ULL << fls64(max_val_cycles - 1);
 	/* calculate max possible multiplier in order to fit in 64bit */
-	u64 max_mul = div_u64(0xffffffffffffffffULL, max_val_cycles_rounded);
+	u64 max_mul = div64_u64(ULLONG_MAX, max_val_cycles_rounded);
 
 	/* This comes from the reverse of clocksource_khz2mult */
 	return ilog2(div_u64(max_mul * freq_khz, 1000000));
