[PATCH 5.4 124/411] drm/msm/mdp5: Return error code in mdp5_pipe_release when deadlock is detected

Greg Kroah-Hartman
2022-06-13T11:20:58Z

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