Re: [PATCH v4 14/24] PM / devfreq: tegra30: Ensure that target freq won't overflow

Chanwoo Choi
2019-07-16T12:27:40Z

On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
> Potentially very high boosting could cause an integer overflow for a
> highly clocked memory after conversion to MHz.
>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/devfreq/tegra30-devfreq.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 2f59c78930bd..0de1efdaabf4 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -460,6 +460,7 @@ static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
> unsigned long target_freq;
>
> target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq;
> + target_freq = min(target_freq, ULONG_MAX / KHZ);

Did you meet this corner case?
If have to change it, you better to use 'tegra->max_freq' as following:
min(target_freq, tegra->max_freq);

> target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);
>
> return target_freq;
>

--
Best Regards,
Chanwoo Choi
Samsung Electronics