Re: [PATCH v8] tcp: move seq_to_tap update to when frame is queued

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Jun 04, 2024 at 11:30:20PM +0200, Stefano Brivio wrote:
> On Tue,  4 Jun 2024 14:29:08 -0400
> Jon Maloy <jmaloy@redhat.com> wrote:
> 
> > +/**
> > + * tcp_revert_seq() - Revert affected conn->seq_to_tap after failed transmission
> > + * @conns:       Array of connection pointers corresponding to queued frames
> > + * @frames:      Two-dimensional array containing queued frames with sub-iovs
> > + * @num_frames:  Number of entries in the two arrays to be compared
> > + */
> > +static void tcp_revert_seq(struct tcp_tap_conn **conns, struct iovec (*frames)[TCP_NUM_IOVS],
> > +			   int num_frames)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < num_frames; i++) {
> > +		struct tcp_tap_conn *conn = conns[i];
> > +		struct tcphdr *th = frames[i][TCP_IOV_PAYLOAD].iov_base;
> > +		uint32_t seq = ntohl(th->seq);
> > +
> > +		if (SEQ_LE(conn->seq_to_tap, seq))
> > +			continue;
> 
> See:
>   https://archives.passt.top/passt-dev/Zkr_4LkjDImgFqSi@zatzit
>   https://archives.passt.top/passt-dev/ZlkrBFkxliCCT3st@zatzit
> 
> about this if (SEQ_LE) ... continue;

As Jon mentioned in Monday's call, this looks weird in isolation but
makes sense after the change in the second patch.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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