[Freedreno] [PATCH v3 1/2] drm/msm/mdp5: Return error code in mdp5_pipe_release when deadlock is detected

[Dmitry Baryshkov]

On 06/05/2022 01:01, Rob Clark wrote:
> On Thu, May 5, 2022 at 2:41 PM Jessica Zhang <quic_jesszhan at quicinc.com> wrote:
>>
>> mdp5_get_global_state runs the risk of hitting a -EDEADLK when acquiring
>> the modeset lock, but currently mdp5_pipe_release doesn't check for if
>> an error is returned. Because of this, there is a possibility of
>> mdp5_pipe_release hitting a NULL dereference error.
>>
>> To avoid this, let's have mdp5_pipe_release check if
>> mdp5_get_global_state returns an error and propogate that error.
>>
>> Changes since v1:
>> - Separated declaration and initialization of *new_state to avoid
>>    compiler warning
>> - Fixed some spelling mistakes in commit message
>>
>> Changes since v2:
>> - Return 0 in case where hwpipe is NULL as this is considered normal
>>    behavior
>> - Added 2nd patch in series to fix a similar NULL dereference issue in
>>    mdp5_mixer_release
>>
>> Reported-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>
>> Signed-off-by: Jessica Zhang <quic_jesszhan at quicinc.com>
> 
> Fixes: 7907a0d77cb4 ("drm/msm/mdp5: Use the new private_obj state")
> Reviewed-by: Rob Clark <robdclark at gmail.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> 
>> ---
>>   drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.c  | 15 +++++++++++----
>>   drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.h  |  2 +-
>>   drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 20 ++++++++++++++++----
>>   3 files changed, 28 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.c
>> index ba6695963aa6..a4f5cb90f3e8 100644
>> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.c
>> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.c
>> @@ -119,18 +119,23 @@ int mdp5_pipe_assign(struct drm_atomic_state *s, struct drm_plane *plane,
>>          return 0;
>>   }
>>
>> -void mdp5_pipe_release(struct drm_atomic_state *s, struct mdp5_hw_pipe *hwpipe)
>> +int mdp5_pipe_release(struct drm_atomic_state *s, struct mdp5_hw_pipe *hwpipe)
>>   {
>>          struct msm_drm_private *priv = s->dev->dev_private;
>>          struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(priv->kms));
>>          struct mdp5_global_state *state = mdp5_get_global_state(s);
>> -       struct mdp5_hw_pipe_state *new_state = &state->hwpipe;
>> +       struct mdp5_hw_pipe_state *new_state;
>>
>>          if (!hwpipe)
>> -               return;
>> +               return 0;
>> +
>> +       if (IS_ERR(state))
>> +               return PTR_ERR(state);
>> +
>> +       new_state = &state->hwpipe;
>>
>>          if (WARN_ON(!new_state->hwpipe_to_plane[hwpipe->idx]))
>> -               return;
>> +               return -EINVAL;
>>
>>          DBG("%s: release from plane %s", hwpipe->name,
>>                  new_state->hwpipe_to_plane[hwpipe->idx]->name);
>> @@ -141,6 +146,8 @@ void mdp5_pipe_release(struct drm_atomic_state *s, struct mdp5_hw_pipe *hwpipe)
>>          }
>>
>>          new_state->hwpipe_to_plane[hwpipe->idx] = NULL;
>> +
>> +       return 0;
>>   }
>>
>>   void mdp5_pipe_destroy(struct mdp5_hw_pipe *hwpipe)
>> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.h b/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.h
>> index 9b26d0761bd4..cca67938cab2 100644
>> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.h
>> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_pipe.h
>> @@ -37,7 +37,7 @@ int mdp5_pipe_assign(struct drm_atomic_state *s, struct drm_plane *plane,
>>                       uint32_t caps, uint32_t blkcfg,
>>                       struct mdp5_hw_pipe **hwpipe,
>>                       struct mdp5_hw_pipe **r_hwpipe);
>> -void mdp5_pipe_release(struct drm_atomic_state *s, struct mdp5_hw_pipe *hwpipe);
>> +int mdp5_pipe_release(struct drm_atomic_state *s, struct mdp5_hw_pipe *hwpipe);
>>
>>   struct mdp5_hw_pipe *mdp5_pipe_init(enum mdp5_pipe pipe,
>>                  uint32_t reg_offset, uint32_t caps);
>> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
>> index 228b22830970..979458482841 100644
>> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
>> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
>> @@ -311,12 +311,24 @@ static int mdp5_plane_atomic_check_with_state(struct drm_crtc_state *crtc_state,
>>                                  mdp5_state->r_hwpipe = NULL;
>>
>>
>> -                       mdp5_pipe_release(state->state, old_hwpipe);
>> -                       mdp5_pipe_release(state->state, old_right_hwpipe);
>> +                       ret = mdp5_pipe_release(state->state, old_hwpipe);
>> +                       if (ret)
>> +                               return ret;
>> +
>> +                       ret = mdp5_pipe_release(state->state, old_right_hwpipe);
>> +                       if (ret)
>> +                               return ret;
>> +
>>                  }
>>          } else {
>> -               mdp5_pipe_release(state->state, mdp5_state->hwpipe);
>> -               mdp5_pipe_release(state->state, mdp5_state->r_hwpipe);
>> +               ret = mdp5_pipe_release(state->state, mdp5_state->hwpipe);
>> +               if (ret)
>> +                       return ret;
>> +
>> +               ret = mdp5_pipe_release(state->state, mdp5_state->r_hwpipe);
>> +               if (ret)
>> +                       return ret;
>> +
>>                  mdp5_state->hwpipe = mdp5_state->r_hwpipe = NULL;
>>          }
>>
>> --
>> 2.35.1
>>


-- 
With best wishes
Dmitry