From: Lukasz Czapnik <[email protected]>
In ice_sched_bw_to_rl_profile(), the loop over 64 bits computes the
scheduler timestamp rate as:
ts_rate = div64_long((s64)hw->psm_clk_freq,
pow_result * ICE_RL_PROF_TS_MULTIPLIER);
where pow_result = BIT_ULL(i). For large values of i, the product
pow_result * ICE_RL_PROF_TS_MULTIPLIER overflows u64 before being used
as the divisor, producing incorrect ts_rate values and potentially
undefined behaviour.
Fix this by pre-computing ts_freq = hw->psm_clk_freq /
ICE_RL_PROF_TS_MULTIPLIER once before the loop and then dividing only
by pow_result inside the loop. The division order avoids the overflow
while preserving the same mathematical result. Declare ts_freq as s64
to match the type domain of the surrounding arithmetic and avoid a
redundant cast at the use site.
While at it, scope the loop variable i to the for statement itself.
Fixes: 1ddef455f4a8 ("ice: Add NDO callback to set the maximum per-queue
bitrate")
Signed-off-by: Lukasz Czapnik <[email protected]>
Signed-off-by: Aleksandr Loktionov <[email protected]>
---
drivers/net/ethernet/intel/ice/ice_sched.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/intel/ice/ice_sched.c
b/drivers/net/ethernet/intel/ice/ice_sched.c
index fff0c1a..edea262c 100644
--- a/drivers/net/ethernet/intel/ice/ice_sched.c
+++ b/drivers/net/ethernet/intel/ice/ice_sched.c
@@ -3237,12 +3237,12 @@ static int
ice_sched_bw_to_rl_profile(struct ice_hw *hw, u32 bw,
struct ice_aqc_rl_profile_elem *profile)
{
+ s64 ts_freq = hw->psm_clk_freq / ICE_RL_PROF_TS_MULTIPLIER;
s64 bytes_per_sec, ts_rate, mv_tmp;
int status = -EINVAL;
bool found = false;
s32 encode = 0;
s64 mv = 0;
- s32 i;
/* Bw settings range is from 0.5Mb/sec to 100Gb/sec */
if (bw < ICE_SCHED_MIN_BW || bw > ICE_SCHED_MAX_BW)
@@ -3255,8 +3255,7 @@ ice_sched_bw_to_rl_profile(struct ice_hw *hw, u32 bw,
- for (i = 0; i < 64; i++) {
+ for (int i = 0; i < 64; i++) {
u64 pow_result = BIT_ULL(i);
- ts_rate = div64_long((s64)hw->psm_clk_freq,
- pow_result * ICE_RL_PROF_TS_MULTIPLIER);
+ ts_rate = div64_long(ts_freq, pow_result);
if (ts_rate <= 0)
continue;
--
2.52.0
