Re: [PATCH net 1/5] net: tls: handle -EBUSY on async encrypt/decrypt requests

On Fri, Sep 08, 2023 at 05:55:59PM +0200, Sabrina Dubroca wrote:

Uh, ok, I didn't know that, thanks for explaining. When I was fixing
this code I couldn't find a mention of what the expectations for
MAY_BACKLOG are. Could you add a comment describing this in the
headers (either for #define CRYPTO_TFM_REQ_MAY_BACKLOG or
aead_request_set_callback, wherever is more appropriate). MAY_BACKLOG
is used by both tls and tipc (talking only about networking) and
neither seem to respect this need to back off.

Patches are welcome :)

A bit of history: at the beginning we always dropped requests
that we couldn't queue because the only user was IPsec so this
is the expected behaviour.

When storage crypto support was added there was a need for reliable
handling of resource constraints so that's why MAY_BACKLOG was added.
However, the expectation is obviously that you must stop sending new
requests once you run into the resource constraint.

Jakub, I guess we should drop the CRYPTO_TFM_REQ_MAY_BACKLOG for net,
and maybe consider adding it back (with the back off) in
net-next. Probably not urgent considering that nobody seems to have
run into this bug so far.

I think that would be the prudent action.

Thanks,
-- 
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