On Tue, Apr 07, 2026 at 04:04:05PM -0400, Soumyadeep Hore wrote:
> Normalize ppm to an unsigned magnitude before using it in the
> increment value scaling path.
>
> This avoids negating INT64_MIN and also prevents subtracting 62
> from the reduced log sum unless the sum is still above the
> overflow threshold reported by Coverity.
>
> Coverity issue: 501832
>
> Signed-off-by: Soumyadeep Hore <[email protected]>
> ---
> v2:
> -Addressed Bruce's comments
> ---
The code is a lot cleaner, but unfortunately the 32-bit builds are failing
due to a lack of 128-bit type. I'd suggest keeping thge 128-bit calculation
for simplicity on 64-bit platforms, and maybe adding back your original
calculation for 32-bit systems.
/Bruce
> drivers/net/intel/idpf/idpf_ethdev.c | 38 ++++------------------------
> 1 file changed, 5 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/net/intel/idpf/idpf_ethdev.c
> b/drivers/net/intel/idpf/idpf_ethdev.c
> index 5e57a45775..23a2af6332 100644
> --- a/drivers/net/intel/idpf/idpf_ethdev.c
> +++ b/drivers/net/intel/idpf/idpf_ethdev.c
> @@ -1005,42 +1005,14 @@ idpf_timesync_adjust_freq(struct rte_eth_dev *dev,
> int64_t ppm)
> struct idpf_vport *vport = dev->data->dev_private;
> struct idpf_adapter *adapter = vport->adapter;
> struct idpf_ptp *ptp = adapter->ptp;
> - int64_t incval, diff = 0;
> - bool negative = false;
> - uint64_t div, rem;
> - uint64_t divisor = 1000000ULL << 16;
> - int shift;
> + uint64_t incval;
> + __int128 diff;
> int ret;
>
> + /* ppm is scaled by 2^16 to match Linux adjfine. */
> incval = ptp->base_incval;
> -
> - if (ppm < 0) {
> - negative = true;
> - ppm = -ppm;
> - }
> -
> - /* can incval * ppm overflow ? */
> - if (rte_log2_u64(incval) + rte_log2_u64(ppm) > 62) {
> - rem = ppm % divisor;
> - div = ppm / divisor;
> - diff = div * incval;
> - ppm = rem;
> -
> - shift = rte_log2_u64(incval) + rte_log2_u64(ppm) - 62;
> - if (shift > 0) {
> - /* drop precision */
> - ppm >>= shift;
> - divisor >>= shift;
> - }
> - }
> -
> - if (divisor)
> - diff = diff + incval * ppm / divisor;
> -
> - if (negative)
> - incval -= diff;
> - else
> - incval += diff;
> + diff = ((__int128)incval * ppm) / (1000000LL << 16);
> + incval += (int64_t)diff;
>
> ret = idpf_ptp_adj_dev_clk_fine(adapter, incval);
> if (ret) {
> --
> 2.47.1
>
