Re: [PATCH] tpm: Make timeout logic simpler and more robust

Jarkko Sakkinen
2019-03-13T13:22:39Z

On Tue, Mar 12, 2019 at 01:04:58PM -0400, Mimi Zohar wrote:
> On Mon, 2019-03-11 at 16:54 -0700, Calvin Owens wrote:
> > We're having lots of problems with TPM commands timing out, and we're
> > seeing these problems across lots of different hardware (both v1/v2).
> >
> > I instrumented the driver to collect latency data, but I wasn't able to
> > find any specific timeout to fix: it seems like many of them are too
> > aggressive. So I tried replacing all the timeout logic with a single
> > universal long timeout, and found that makes our TPMs 100% reliable.
> >
> > Given that this timeout logic is very complex, problematic, and appears
> > to serve no real purpose, I propose simply deleting all of it.
>
> Normally before sending such a massive change like this, included in
> the bug report or patch description, there would be some indication as
> to which kernel introduced a regression.  Has this always been a
> problem?  Is this something new?  How new?

Also: is the problem in timeouts, durations or both. Does make sense
to fix something that isn't broken...

/Jarkko