Subject: Re: [PATCH net-next 6/6] selftests: drv-net: gro: add a test for bad IPv4 csum

From: Jakub Kicinski <[email-masked]>
Date: Wed, 1 Apr 2026 19:10:30 -0700

On Wed, 01 Apr 2026 20:28:46 -0400 Willem de Bruijn wrote:
> >  	/* ip sub-tests - IPv4 only */
> > +	} else if (strcmp(testname, "ip_csum") == 0) {
> > +		correct_payload[0] = PAYLOAD_LEN;
> > +		correct_payload[1] = PAYLOAD_LEN;
> > +		printf("bad ip checksum doesn't coalesce: ");
> > +		check_recv_pkts(rxfd, correct_payload, 2);  
> 
> This verifies that a packet with bad csum does not coalesce to a valid
> packet. Perhaps too paranoid but, do you also want to test the reverse
> case?

Will do, easy enough. Tho TBH I can't think of a case where this would
matter. Bad csum pkt must bypass all GRO processing completely right?
Because we don't want a corrupted packet to flush a valid session?
Or you think some implementation may actually feed these packets into
GRO to avoid waiting for a session timeout?