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Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip

From Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Newsgroups linux.kernel
Subject Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip
Date 2017-01-03 20:20 +0100
Message-ID <sVCMO-2nX-13@gated-at.bofh.it> (permalink)
References <sVaQx-7mn-5@gated-at.bofh.it> <sVaQy-7mn-27@gated-at.bofh.it> <sVi1I-4ma-29@gated-at.bofh.it> <sVoAa-v7-5@gated-at.bofh.it>
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On Tue, Jan 03, 2017 at 02:57:37AM +0200, Jarkko Sakkinen wrote:
> On Mon, Jan 02, 2017 at 02:01:01PM -0700, Jason Gunthorpe wrote:
> > On Mon, Jan 02, 2017 at 03:22:07PM +0200, Jarkko Sakkinen wrote:
> > > Since there is only one thread using TPM chip at a time to transmit data
> > > we can migrate struct tpm_buf to struct tpm_chip. This makes the use of
> > > it more fail safe as the buffer is allocated from heap when the device
> > > is created and not for every transaction.
> > 
> > Eh? What? I don't think that is the case..
> > 
> > We don't serialize until we hit tramsit_cmd at which point the buffer
> > is already being used and cannot be shared between threads.
> 
> There is a regression in the patch. All functions that use 'tr_buf'
> should take tpm_mutex first and use TPM_TRANSMIT_UNLOCKED. There's
> also a similar regression in TPM space patch that I have to correct.

No, you can't steal TPM_TRANSMIT_UNLOCKED and tpm_mutex for this, that
is to allow a chain of commands to execute atomicly, so a new lock is
needed just for the tr_buf.

> > Why would the resource manager need a single global tpm buffer? That
> > seems like a big regression from where we have been going. I don't
> > think this is a good idea to go down this road.
> 
> What? 'tr_buf' is not specifically for resource manager. This commit
> makes creating TPM commands more fail-safe because there is no need
> to allocate page for every transmit.

That doesn't seem all that important, honestly. There kernel does not
fail single page allocations without a lot of duress.

> For RM decorations this is really important because I rather would have
> them fail as rarely as possible. If this would become a scalability
> issue then the granularity could be reconsidered.

Why? The RM design already seems to have the prepare/commit/abort
kind of model so it can already fail. What does it matter if the
caller can fail before getting that far?

It seems like alot of dangerous churn to introduce a new locking model
without a really good reason...

Jason

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[PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-02 14:30 +0100
  [PATCH RFC 2/4] tpm: validate TPM 2.0 commands Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-02 14:30 +0100
    Re: [tpmdd-devel] [PATCH RFC 2/4] tpm: validate TPM 2.0 commands James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-04 19:30 +0100
    Re: [tpmdd-devel] [PATCH RFC 2/4] tpm: validate TPM 2.0 commands Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 19:50 +0100
  [PATCH RFC 3/4] tpm: export tpm2_flush_context_cmd Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-02 14:30 +0100
  [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for TPM 2.0 Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-02 14:30 +0100
    Re: [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for  TPM 2.0 Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-02 22:20 +0100
      Re: [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for  TPM 2.0 Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 05:10 +0100
        Re: [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for  TPM 2.0 Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-03 19:50 +0100
          Re: [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for  TPM 2.0 Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 13:50 +0100
        Re: [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for  TPM 2.0 Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-03 20:20 +0100
          Re: [PATCH RFC 4/4] tpm: add the infrastructure for TPM space for  TPM 2.0 Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 13:50 +0100
    Re: [tpmdd-devel] [PATCH RFC 4/4] tpm: add the infrastructure for  TPM    space for TPM 2.0 Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-09 23:20 +0100
  [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-02 14:30 +0100
    Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-02 22:10 +0100
      Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 05:10 +0100
        Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-03 20:20 +0100
          Re: [PATCH RFC 1/4] tpm: migrate struct tpm_buf to struct tpm_chip Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 13:40 +0100
  Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-02 17:40 +0100
    Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-02 22:50 +0100
      Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-03 06:30 +0100
        Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 14:50 +0100
          Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-03 17:20 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 19:40 +0100
              Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 20:20 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-04 02:30 +0100
        Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-03 23:00 +0100
          Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 14:10 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 18:00 +0100
        Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Andy Lutomirski <luto@kernel.org> - 2017-01-04 06:50 +0100
          Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 14:10 +0100
      Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 15:00 +0100
        Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-03 17:40 +0100
          Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 19:50 +0100
          Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-03 22:50 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-03 23:50 +0100
              Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 01:20 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-04 01:40 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 02:00 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 14:00 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-04 16:00 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-04 20:10 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 20:30 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 20:30 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-04 00:30 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-04 13:50 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Ken Goldman <kgoldman@us.ibm.com> - 2017-01-04 15:00 +0100
    Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-03 05:10 +0100
    Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-03 22:40 +0100
      Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-01-03 23:10 +0100
  RE: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager "Fuchs, Andreas" <andreas.fuchs@sit.fraunhofer.de> - 2017-01-05 17:10 +0100
    Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-05 18:30 +0100
      Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-05 19:10 +0100
        Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Andreas Fuchs <andreas.fuchs@sit.fraunhofer.de> - 2017-01-06 09:50 +0100
      Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-05 19:40 +0100
        Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-05 21:00 +0100
          Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-05 21:00 +0100
            Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-05 23:30 +0100
              Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-06 01:00 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-06 01:40 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Andreas Fuchs <andreas.fuchs@sit.fraunhofer.de> - 2017-01-06 10:10 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-06 20:20 +0100
                Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-01-06 20:10 +0100
              Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager James Bottomley <jejb@linux.vnet.ibm.com> - 2017-01-06 02:40 +0100
          Re: [PATCH RFC 0/4] RFC: in-kernel resource manager Ken Goldman <kgoldman@us.ibm.com> - 2017-01-10 20:20 +0100
    Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2017-01-09 23:40 +0100
      Re: [tpmdd-devel] [PATCH RFC 0/4] RFC: in-kernel resource manager Andreas Fuchs <andreas.fuchs@sit.fraunhofer.de> - 2017-01-11 11:10 +0100

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