[PATCH] drm/amdgpu: Fix regression in adjusting power table/profile

[Paweł Gronowski]

Hello Matt,

Thank you for your testing. It seems that my gpu (RX 570) does not support the
vc setting so I can not exactly reproduce the issue. However I did trace the
code path the test case takes and it seems to correctly pass through the while
loop that parses the input and fails only in amdgpu_dpm_odn_edit_dpm_table.
The 'parameter' array is populated the same way as the original code did. Since
the amdgpu_dpm_odn_edit_dpm_table is reached, I think that your problem is
unfortunately caused by something else.


Paweł Gronowski

On Thu, Jul 30, 2020 at 08:49:41AM -0600, Matt Coffin wrote:
> Hello all, I just did some testing with this applied, and while it no
> longer returns -EINVAL, running `sudo sh -c 'echo "vc 2 2150 1195" >
> /sys/class/drm/card1/device/pp_od_clk_voltage'` results in `sh` spiking
> to, and staying at 100% CPU usage, with no indicating information in
> `dmesg` from the kernel.
> 
> It appeared to work at least ONCE, but potentially not after.
> 
> This is not unique to Navi, and caused the problem on a POLARIS10 card
> as well.
> 
> Sorry for the bad news, and thanks for any insight you may have,
> Matt Coffin
> 
> On 7/29/20 8:53 PM, Alex Deucher wrote:
> > On Wed, Jul 29, 2020 at 10:20 PM Paweł Gronowski <me at woland.xyz> wrote:
> >>
> >> Regression was introduced in commit 38e0c89a19fd
> >> ("drm/amdgpu: Fix NULL dereference in dpm sysfs handlers") which
> >> made the set_pp_od_clk_voltage and set_pp_power_profile_mode return
> >> -EINVAL for previously valid input. This was caused by an empty
> >> string (starting at the \0 character) being passed to the kstrtol.
> >>
> >> Signed-off-by: Paweł Gronowski <me at woland.xyz>
> > 
> > Applied.  Thanks!
> > 
> > Alex
> > 
> >> ---
> >>  drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 9 +++++++--
> >>  1 file changed, 7 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> >> index ebb8a28ff002..cbf623ff03bd 100644
> >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> >> @@ -778,12 +778,14 @@ static ssize_t amdgpu_set_pp_od_clk_voltage(struct device *dev,
> >>                 tmp_str++;
> >>         while (isspace(*++tmp_str));
> >>
> >> -       while ((sub_str = strsep(&tmp_str, delimiter)) != NULL) {
> >> +       while ((sub_str = strsep(&tmp_str, delimiter)) && *sub_str) {
> >>                 ret = kstrtol(sub_str, 0, &parameter[parameter_size]);
> >>                 if (ret)
> >>                         return -EINVAL;
> >>                 parameter_size++;
> >>
> >> +               if (!tmp_str)
> >> +                       break;
> >>                 while (isspace(*tmp_str))
> >>                         tmp_str++;
> >>         }
> >> @@ -1635,11 +1637,14 @@ static ssize_t amdgpu_set_pp_power_profile_mode(struct device *dev,
> >>                         i++;
> >>                 memcpy(buf_cpy, buf, count-i);
> >>                 tmp_str = buf_cpy;
> >> -               while ((sub_str = strsep(&tmp_str, delimiter)) != NULL) {
> >> +               while ((sub_str = strsep(&tmp_str, delimiter)) && *sub_str) {
> >>                         ret = kstrtol(sub_str, 0, &parameter[parameter_size]);
> >>                         if (ret)
> >>                                 return -EINVAL;
> >>                         parameter_size++;
> >> +
> >> +                       if (!tmp_str)
> >> +                               break;
> >>                         while (isspace(*tmp_str))
> >>                                 tmp_str++;
> >>                 }
> >> --
> >> 2.25.1
> >>
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>