On 12/20/21 5:31 PM, Stefan Berger wrote:
>
> On 12/20/21 20:13, Jason Gunthorpe wrote:
>> On Mon, Dec 20, 2021 at 08:05:58PM -0500, Stefan Berger wrote:
>>
>>> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
>>> index ddaeceb7e109..4cb908349b31 100644
>>> +++ b/drivers/char/tpm/tpm-chip.c
>>> @@ -473,15 +473,8 @@ static void tpm_del_char_device(struct tpm_chip *chip)
>>> mutex_unlock(&idr_lock);
>>>
>>> /* Make the driver uncallable. */
>>> - down_write(&chip->ops_sem);
>>> - if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>>> - if (!tpm_chip_start(chip)) {
>>> - tpm2_shutdown(chip, TPM2_SU_CLEAR);
>>> - tpm_chip_stop(chip);
>>> - }
>>> - }
>>> - chip->ops = NULL;
>>> - up_write(&chip->ops_sem);
>>> + if (chip->ops)
>> ops cannot be read without locking
>
> This here could be an alternative:
I still think code de-duplication is a good thing. Maybe combine the two
approaches. Call tpm_class_shutdown from tpm_del_char_device and add a chip->ops
check in tpm_class_shutdown to ensure we only do the shutdown when chip->ops is
valid.
-Tyrel
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index ddaeceb7e109..7772b475ebc0 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -474,7 +474,7 @@ static void tpm_del_char_device(struct tpm_chip *chip)
>
> /* Make the driver uncallable. */
> down_write(&chip->ops_sem);
> - if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> + if (chip->ops && chip->flags & TPM_CHIP_FLAG_TPM2) {
> if (!tpm_chip_start(chip)) {
> tpm2_shutdown(chip, TPM2_SU_CLEAR);
> tpm_chip_stop(chip);
>
> Stefan
>
>
>>
>> Jason
