On 22/07/2021 16:39, Eric Dumazet wrote:

On Thu, Jul 22, 2021 at 3:33 PM Boris Pismenny [off-list ref] wrote:

quoted

Sorry. My response above was about skb_condense which I've confused with
tcp_collapse.

In tcp_collapse, we could allow the copy, but the problem is CRC, which
like TLS's skb->decrypted marks that the data passed the digest
validation in the NIC. If we allow collapsing SKBs with mixed marks, we
will need to force software copy+crc verification. As TCP collapse is
indeed rare and the offload is opportunistic in nature, we can make this
change and submit another version, but I'm confused; why was it OK for
TLS, while it is not OK for DDP+CRC?

Ah.... I guess I was focused on the DDP part, while all your changes
are really about the CRC part.

Perhaps having an accessor to express the CRC status (and not be
confused by the DDP part)
 could help the intent of the code.

An accessor function sounds like a great idea for readability, thanks Eric!

We will re-spin the series and add it to v6.