| Message ID | 20190707223303.6755-15-digetx@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | More improvements for Tegra30 devfreq driver | expand |
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; >
16.07.2019 15:30, Chanwoo Choi пишет: > 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? I can't recall that, technically it could happen and I don't feel comfortable by having potential integer overflows anyway. > If have to change it, you better to use 'tegra->max_freq' as following: > min(target_freq, tegra->max_freq); The 'tegra->max_freq' will work here, but 'ULONG_MAX / KHZ' is a constant value which is also correct and doesn't case any harm. Probably will be even more expressive to write this as: target_freq = dev->avg_freq + dev->boost_freq; target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq); return min(target_freq, tegra->max_freq); Thank you very much for the reviews!
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); target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq); return target_freq;
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(+)