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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 31 Jan 2019 13:58:35 -0800
Message-ID: <CAHk-=wgPCL9WgkwvK5ehJxg7Df1DHQqGZ0KtBxtjN93QjzUyog@mail.gmail.com>
Subject: Re: Getting weird TPM error after rebasing my tree to security/next-general
To:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc:     tomas.winkler@intel.com, Jason Gunthorpe <jgg@ziepe.ca>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
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On Thu, Jan 31, 2019 at 12:47 PM Jarkko Sakkinen
<jarkko.sakkinen@linux.intel.com> wrote:
>
> I'll try it first thing when I wake up tomorrow (11PM in Finland ATM).

Thanks.

> Appreciate for taking time on this.

Hey, it was my commit that broke it for you. Even if it happened to
work before, and only did so by pure luck, it was a functional
regression.

I get very upset when other developers don't step up when *their*
changes break something, and I don't consider "it shouldn't have
worked in the first place" to be a valid excuse. You broke it, you'd
better fix it.

So I had better fix my own mess too, in order to not look too hypocritical.

And I was very aware that hardcoding the memcpy_*io() access patterns
might break something. I just _hoped_ it wouldn't, because we actually
ended up going back to the very original access patterns (but it was
from a long long time ago).

In fact, while it's slightly annoying, in many ways it's actually good
that we found breakage, and could pinpoint exactly *why* it broke.
That does validate the whole "we shouldn't just depend on the random
implementation detail of 'memcpy()'" argument.

So I'll wait to hear back whether that patch fixes things for you, but
I _think_ it will, and we'll be better off in the long range with this
whole thing.

              Linus