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

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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.

Only /dev/tpmX has any sort of locking, but even that is
designed to be optional (eg I patch it out of my kernels), and only
covers userspace, not contention with in-kernel threads.

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.

> -	tpm_buf_append(buf, (u8 *) &value2, 4);
> +	tpm_buf_append(buf, (u8 *)&value2, 4);

Please try and avoid this sort of churn in patches that change things..

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
  [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
  [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: [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 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 05:10 +0100

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