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    Subject[PATCH 4.7 31/31] tpm_crb: fix crb_req_canceled behavior
    Date
    4.7-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

    commit 72fd50e14e46dc0edf360631bdece87c2f066a97 upstream.

    The req_canceled() callback is used by tpm_transmit() periodically to
    check whether the request has been canceled while it is receiving a
    response from the TPM.

    The TPM_CRB_CTRL_CANCEL register was cleared already in the crb_cancel
    callback, which has two consequences:

    * Cancel might not happen.
    * req_canceled() always returns zero.

    A better place to clear the register is when starting to send a new
    command. The behavior of TPM_CRB_CTRL_CANCEL is described in the
    section 5.5.3.6 of the PTP specification.

    Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
    Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/char/tpm/tpm_crb.c | 7 +++++--
    1 file changed, 5 insertions(+), 2 deletions(-)

    --- a/drivers/char/tpm/tpm_crb.c
    +++ b/drivers/char/tpm/tpm_crb.c
    @@ -142,6 +142,11 @@ static int crb_send(struct tpm_chip *chi
    struct crb_priv *priv = chip->vendor.priv;
    int rc = 0;

    + /* Zero the cancel register so that the next command will not get
    + * canceled.
    + */
    + iowrite32(0, &priv->cca->cancel);
    +
    if (len > ioread32(&priv->cca->cmd_size)) {
    dev_err(&chip->dev,
    "invalid command count value %x %zx\n",
    @@ -175,8 +180,6 @@ static void crb_cancel(struct tpm_chip *

    if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
    dev_err(&chip->dev, "ACPI Start failed\n");
    -
    - iowrite32(0, &priv->cca->cancel);
    }

    static bool crb_req_canceled(struct tpm_chip *chip, u8 status)

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