linux-kernel - Re: [PATCH v3 0/2] tpm: add support for nonblocking operation

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Date:   Thu, 21 Jun 2018 20:17:46 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Tadeusz Struk <tadeusz.struk@...el.com>
Cc:     jgg@...pe.ca, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, philip.b.tricca@...el.com,
        James.Bottomley@...senPartnership.com,
        "Dock, Deneen T" <deneen.t.dock@...el.com>
Subject: Re: [PATCH v3 0/2] tpm: add support for nonblocking operation

On Tue, Jun 19, 2018 at 05:45:35PM -0700, Tadeusz Struk wrote:
> Hi Jarkko,
> Thanks for reviewing the patch.
> There are applications/frameworks where a worker thread is not an option.
> Take for example the IoT use-cases and frameworks like IoT.js, or "Node.js for IoT".
> They are all single threaded, event-driven frameworks, using non-blocking I/O as the base of their processing model.
> Similarly embedded applications, which are basically just a single threaded event loop, quite often don't use threads because of resources constrains.
> 
> If your concern is that user space will not adopt to this, I can say that TSS library [1] is currently blocked on this feature, and we can not enable some of the use-cases mentioned above because of this.
> 
> Thanks,
> Tadeusz
> 
> [1] https://github.com/tpm2-software/tpm2-tss

I put this into "mathematical" terms. TPM is by nature is blocking. It
does not scale this way so you are essentially just simulating
non-blocking behaviour.

/Jarkko