linux-kernel - Re: [PATCHv2 1/2] hwrng: optee: handle unlimited data rates

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Date:   Fri, 24 Jul 2020 18:54:07 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Jorge Ramirez-Ortiz <jorge@...ndries.io>
Cc:     Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, ricardo@...ndries.io,
        Michael Scott <mike@...ndries.io>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        op-tee@...ts.trustedfirmware.org,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2 1/2] hwrng: optee: handle unlimited data rates

On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@...ndries.io> wrote:
>
> Data rates of MAX_UINT32 will schedule an unnecessary one jiffy
> timeout on the call to msleep. Avoid this scenario by using 0 as the
> unlimited data rate.
>
> Signed-off-by: Jorge Ramirez-Ortiz <jorge@...ndries.io>
> ---
>  drivers/char/hw_random/optee-rng.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Sounds good to me. FWIW:

Reviewed-by: Sumit Garg <sumit.garg@...aro.org>

-Sumit

> diff --git a/drivers/char/hw_random/optee-rng.c b/drivers/char/hw_random/optee-rng.c
> index 49b2e02537dd..5bc4700c4dae 100644
> --- a/drivers/char/hw_random/optee-rng.c
> +++ b/drivers/char/hw_random/optee-rng.c
> @@ -128,7 +128,7 @@ static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
>                 data += rng_size;
>                 read += rng_size;
>
> -               if (wait) {
> +               if (wait && pvt_data->data_rate) {
>                         if (timeout-- == 0)
>                                 return read;
>                         msleep((1000 * (max - read)) / pvt_data->data_rate);
> --
> 2.17.1
>