nvme-tls and TCP window full

[Hannes Reinecke]

Hi Sagi,

I'm currently debugging my nvme-tls patches; with the rebase to latest 
linus' head things started to behave erratically as occasionally a CQE 
was never received, triggering a reset.

Originally I thought it's my read_sock() implementation which is to 
blame, but then I fixed wireshark to do a proper frame dissecting 
(wireshark merge req #11359), and found that it's rather an issue with 
TCP window becoming full.
While this is arguably an issue with the sender (which is trying to send 
32k worth of data in one packet), the connection never recovers from the 
window full state; the command is dropped, never to reappear again.

I would have thought/hoped that we (from the NVMe side) would
be able to handle it better; in particular I'm surprised that we can 
send large chunks of data at all. And that the packet is dropped due to 
a protocol error without us notifying.
So question really is: do we check for the TCP window size somewhere?
If so, where? Or is it something the lower layers have to do for us?

Full packet dissection available on request.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman