On 24/06/2026 11:05, Florian Bezdeka via Intel-wired-lan wrote:
> On Tue, 2026-06-23 at 09:46 +0000, Kwapulinski, Piotr wrote:
>>> -----Original Message-----
>>> From: Intel-wired-lan <[email protected]> On Behalf Of
>>> Ding Meng via Intel-wired-lan
>>> Sent: Monday, June 22, 2026 6:13 AM
>>> To: Nguyen, Anthony L <[email protected]>; Kitszel, Przemyslaw
>>> <[email protected]>; [email protected]; [email protected];
>>> [email protected]; [email protected]; [email protected]; Kiszka, Jan
>>> <[email protected]>; Bezdeka, Florian <[email protected]>
>>> Cc: [email protected]; [email protected];
>>> [email protected]; [email protected]; [email protected]
>>> Subject: [Intel-wired-lan] [PATCH net] igc: Fix RX HW timestamp reporting
>>> when NET_RX_BUSY_POLL is disabled
>>>
>>> When CONFIG_NET_RX_BUSY_POLL is deactivated, fetching RX HW timestamps from
>>> the NIC no longer works as expected.
>>>
>>> This occurs because disabling CONFIG_NET_RX_BUSY_POLL disables the SKB NAPI
>>> mapping in __skb_mark_napi_id(). Consequently, get_timestamp() fails to
>>> perform its driver lookup, and the igc driver's struct
>>> net_device_ops::ndo_get_tstamp is never invoked.
>>>
>>> Instead, get_timestamp() falls back to use shhwtstamps(skb)->hwtstamp, a
>>> field that the driver has not populated.
>>>
>>> Fix this by populating the hwtstamp field with the correct timestamp in the
>>> default timer when CONFIG_NET_RX_BUSY_POLL is disabled.
>>>
>>> Fixes: 069b142f5819 ("igc: Add support for PTP .getcyclesx64()")
>>> Co-developed-by: Florian Bezdeka <[email protected]>
>>> Signed-off-by: Florian Bezdeka <[email protected]>
>>> Signed-off-by: Ding Meng <[email protected]>
>>> ---
>>> drivers/net/ethernet/intel/igc/igc_main.c | 38 ++++++++++++++++-------
>>> 1 file changed, 26 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
>>> b/drivers/net/ethernet/intel/igc/igc_main.c
>>> index 8ac16808023..1da8d7aa76d 100644
>>> --- a/drivers/net/ethernet/intel/igc/igc_main.c
>>> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
>>> @@ -1992,7 +1992,26 @@ static struct sk_buff *igc_build_skb(struct igc_ring
>>> *rx_ring,
>>> return skb;
>>> }
>>>
>>> -static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring,
>>> +static void igc_construct_skb_timestamps(struct igc_adapter *adapter,
>>> + struct sk_buff *skb,
>>> + struct igc_xdp_buff *ctx)
>>> +{
>>> + if (!ctx->rx_ts)
>>> + return;
>>> +#ifdef CONFIG_NET_RX_BUSY_POLL
>>> + skb_shinfo(skb)->tx_flags |= SKBTX_HW_TSTAMP_NETDEV;
>>> + skb_hwtstamps(skb)->netdev_data = ctx->rx_ts; #else
>>> + struct igc_inline_rx_tstamps *tstamps;
>> Please move at the top of the function and add:
>
> That would trigger a "unused variable" warning in the
> CONFIG_NET_RX_BUSY_POLL case.
Put it under #ifndef CONFIG_NET_RX_BUSY_POLL. Variable declarations
need to be on top.
Thanks,
Marcin
> Btw: I was really confused that the #else statement moved to the end of
> the previous line. Might someone be using a wrongly configured mail
> client here?
>
> Florian
>
>> Reviewed-by: Piotr Kwapulinski <[email protected]
>>
>>> +
>>> + tstamps = ctx->rx_ts;
>>> + skb_hwtstamps(skb)->hwtstamp = igc_ptp_rx_pktstamp(adapter,
>>> + tstamps->timer0);
>>> +#endif
>>> +}
>>> +
>
> [snip]
