Re: [PATCH net 1/3] igc: pad preemptible packets before reserving TX timestamps

[Jacob Keller <jacob.e.keller@intel.com>]

On 10/27/2026 9:13 AM, Paul Moses wrote:
>> [Severity: Low]
>> Does this description match the tree this patch applies to?
> 
> It needs to be clear that it is affected by that commit.
> 
>> [Severity: High]
>> With this patch applied on its own, igc_request_tx_tstamp() still runs
>> before igc_tso() and igc_tx_csum(). Can the same shared skb problem come
>> up here?
>>
>> When a GSO skb with a cloned header (for example with a packet tap or tc
>> mirred active) is hardware timestamped:
>>
>> igc_xmit_frame_ring()
>>   igc_request_tx_tstamp()
>>     tstamp->skb = skb_get(skb);
>>   igc_tso()
>>     skb_cow_head(skb, 0)
>>       __skb_cow()
>>         pskb_expand_head()
>>           BUG_ON(skb_shared(skb));
>>
>> igc_tx_csum() can reach pskb_expand_head() the same way, through
>> skb_checksum_help()->skb_ensure_writable(), on a cloned skb.
>>
>> The next patch in this series, "igc: prepare TSO and checksum offloads
>> before TX timestamps", moves igc_tso() and igc_tx_csum() ahead of the
>> timestamp reservation. That fixes this by the end of the series. Should
>> the two patches be backported together, since this one alone leaves the
>> TSO and checksum paths exposed?
>>
> 
> Yes, I maybe need to research how to properly denote this

Personally, I think its clear from the series context.

Thanks,
Jake