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    SubjectRe: [PATCH 1/6] integrity: TPM internel kernel interface
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    > > > +
    > > > +/**
    > > > + * tpm_pcr_read - read a pcr value
    > > > + * @chip_id: tpm chip identifier
    > > > + * Upper 2 bytes: ANY, HW_ONLY or SW_ONLY
    > > > + * Lower 2 bytes: tpm idx # or AN&
    > > > + * @pcr_idx: pcr idx to retrieve
    > > > + * @res_buf: TPM_PCR value
    > > > + * size of res_buf is 20 bytes (or NULL if you don't care)
    > > > + *
    > > > + * The TPM driver should be built-in, but for whatever reason it
    > > > + * isn't, protect against the chip disappearing, by incrementing
    > > > + * the module usage count.
    > > > + */
    > > > +int tpm_pcr_read(u32 chip_id, int pcr_idx, u8 *res_buf)
    > > > +{
    > > > + u8 data[READ_PCR_RESULT_SIZE];
    > > > + int rc;
    > > > + __be32 index;
    > > > + int chip_num = chip_id & TPM_CHIP_NUM_MASK;
    > > > + struct tpm_chip *chip;
    > > > +
    > > > + rcu_read_lock();
    > > > + chip = tpm_chip_lookup(chip_num, chip_id >> TPM_CHIP_TYPE_SHIFT);
    > > > + if (chip == NULL) {
    > > > + rcu_read_unlock();
    > > > + return -ENODEV;
    > > > + }
    > > > + if (!try_module_get(chip->dev->driver->owner)) {
    > > > + rcu_read_unlock();
    > > > + return -ENODEV;
    > > > + }
    > > > + rcu_read_unlock();
    > >
    > > This little bit of lookup, check for NULL, and try_module_get() looks
    > > cut-n-pasted in the next two functions. Should be consolidated.
    > >
    >
    > Same here.
    >
    > > Also, if you need to shift down the chip_id every time anyway, why not
    > > just do it inside the lookup function?
    >
    > tpm_chip_lookup() only needs the chip type, not the entire chip_id, so
    > its usage is probably clearer if written this way.
    >

    Wait.. chip_num, the other parameter, depends on chip_id and a
    previously defined constant, so, you are right, it's saner to just pass
    chip_id to it.. sorry, and thanks. This will be included also on the
    next patchset I'm about to send.

    Rajiv



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