Re: Problem with io_uring splice and KTLS

Sascha Hauer
2023-10-16T07:26:57Z

On Fri, Oct 13, 2023 at 07:45:55AM -0600, Jens Axboe wrote:
> On 10/12/23 11:47 PM, Sascha Hauer wrote:
> > On Thu, Oct 12, 2023 at 07:45:07PM -0600, Jens Axboe wrote:
> >> On 10/12/23 7:34 AM, Sascha Hauer wrote:
> >>> In case you don't have encryption hardware you can create an
> >>> asynchronous encryption module using cryptd. Compile a kernel with
> >>> CONFIG_CRYPTO_USER_API_AEAD and CONFIG_CRYPTO_CRYPTD and start the
> >>> webserver with the '-c' option. /proc/crypto should then contain an
> >>> entry with:
> >>>
> >>> name : gcm(aes)
> >>> driver : cryptd(gcm_base(ctr(aes-generic),ghash-generic))
> >>> module : kernel
> >>> priority : 150
> >>
> >> I did a bit of prep work to ensure I had everything working for when
> >> there's time to dive into it, but starting it with -c doesn't register
> >> this entry. Turns out the bind() in there returns -1/ENOENT.
> >
> > Yes, that happens here as well, that's why I don't check for the error
> > in the bind call. Nevertheless it has the desired effect that the new
> > algorithm is registered and used from there on. BTW you only need to
> > start the webserver once with -c. If you start it repeatedly with -c a
> > new gcm(aes) instance is registered each time.
>
> Gotcha - I wasn't able to trigger the condition, which is why I thought
> perhaps I was missing something.
>
> Can you try the below patch and see if that makes a difference? I'm not
> quite sure why it would since you said it triggers with DEFER_TASKRUN as
> well, and for that kind of notification, you should never hit the paths
> you have detailed in the debug patch.

I can confirm that this patch makes it work for me. I tested with both
software cryptd and also with my original CAAM encryption workload.
IORING_SETUP_SINGLE_ISSUER | IORING_SETUP_DEFER_TASKRUN is not needed.
Both my simple webserver and the original C++ Webserver from our
customer are now working without problems.

Do you think there is a chance getting this change upstream? I'm a bit
afraid the code originally uses signal_pending() instead of
task_sigpending() for a good reason.

Sascha

>
> diff --git a/net/core/stream.c b/net/core/stream.c
> index f5c4e47df165..a9a196587254 100644
> --- a/net/core/stream.c
> +++ b/net/core/stream.c
> @@ -67,7 +67,7 @@ int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
> return -EPIPE;
> if (!*timeo_p)
> return -EAGAIN;
> - if (signal_pending(tsk))
> + if (task_sigpending(tsk))
> return sock_intr_errno(*timeo_p);
>
> add_wait_queue(sk_sleep(sk), &wait);
> @@ -103,7 +103,7 @@ void sk_stream_wait_close(struct sock *sk, long timeout)
> do {
> if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
> break;
> - } while (!signal_pending(current) && timeout);
> + } while (!task_sigpending(current) && timeout);
>
> remove_wait_queue(sk_sleep(sk), &wait);
> }
> @@ -134,7 +134,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
> goto do_error;
> if (!*timeo_p)
> goto do_eagain;
> - if (signal_pending(current))
> + if (task_sigpending(current))
> goto do_interrupted;
> sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
> if (sk_stream_memory_free(sk) && !vm_wait)
>
> --
> Jens Axboe