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    Subject[PATCH 5.10 192/452] drm/msm/mdp5: Return error code in mdp5_pipe_release when deadlock is detected
    Date
    From: Jessica Zhang <quic_jesszhan@quicinc.com>

    [ Upstream commit d59be579fa932c46b908f37509f319cbd4ca9a68 ]

    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@collabora.com>
    Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
    Fixes: 7907a0d77cb4 ("drm/msm/mdp5: Use the new private_obj state")
    Reviewed-by: Rob Clark <robdclark@gmail.com>
    Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
    Patchwork: https://patchwork.freedesktop.org/patch/485179/
    Link: https://lore.kernel.org/r/20220505214051.155-1-quic_jesszhan@quicinc.com
    Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.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 da0799333970..0dc23c86747e 100644
    --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
    +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
    @@ -393,12 +393,24 @@ 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


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