Re: [PATCH] nvmet-tcp: switch to using the crc32c library

[Hannes Reinecke]

On 2/26/25 20:01, Eric Biggers wrote:
> On Wed, Feb 26, 2025 at 10:37:55AM +0100, Hannes Reinecke wrote:
> > ... and it also eliminates a sporadic crash which we've seen
> > where 'snd_hash' wasn't initialized when sending PDUs.
> > Thanks for doing this!
>
> I'm not sure how that could have happened, since the ahash was allocated when
> 'if (queue->hdr_digest || queue->data_digest)' which seemed to match the
> conditions for when it was used.  But yeah, it's certainly nice to not have the
> pointless allocation to worry about.
>
> > (Note to self: check the nvme-tls code for crc32c usage ...)
>
> I have patches for nvme-tls almost ready too.  Just been taking my time since
> I've been updating all other users of "crc32" and "crc32c" in the kernel too.
> And I need to decide what to do about skb_copy_and_hash_datagram_iter().
If it were me I would _love_ to switch the nvme-tcp recv patch over to 
recvmsg and kill the ->read_sock() implementation.
->read_sock uses a completely different codepath in tls_sw, and nvme is
the only user of that. So there's a fair chance that we might miss any
improvements or fixes.

Plus we currently have no good way of handling TLS records from 
->read_sock(), which is something we might want to do in the future.

So if we had an equivalent for skb_copy_and_hash_iter() for recvmsg()
I could revisit my original patchset and work on getting ->read_sock()
replaced.

Cheers,

Hannes
--
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@xxxxxxx                                +49 911 74053 688
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