drm/vc4: kms: Fix IS_ERR() vs NULL check for vc4_kms

The drm_atomic_get_new_private_obj_state() function returns NULL
on error path, drm_atomic_get_old_private_obj_state() function
returns NULL on error path, too, they does not return error pointers.

By the way, vc4_hvs_get_new/old_global_state() should return
ERR_PTR(-EINVAL), otherwise there will be null-ptr-defer issue,
such as follows:

In function vc4_atomic_commit_tail():
  |-- old_hvs_state = vc4_hvs_get_old_global_state(state); <-- return NULL
  |-- if (WARN_ON(IS_ERR(old_hvs_state))) <-- no return
  |-- unsigned long state_rate = max(old_hvs_state->core_clock_rate,
	new_hvs_state->core_clock_rate); <-- null-ptr-defer

Fixes: 9ec03d7f1ed3 ("drm/vc4: kms: Wait on previous FIFO users before a commit")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20221110094445.2930509-6-cuigaosheng1@huawei.com

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 4419e810103de3e77525163226d7bbd7270d5b9b..0a6347c05df491f72546fedcf43766de10af3b42 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -197,8 +197,8 @@ vc4_hvs_get_new_global_state(struct drm_atomic_state *state)
        struct drm_private_state *priv_state;
 
        priv_state = drm_atomic_get_new_private_obj_state(state, &vc4->hvs_channels);
-       if (IS_ERR(priv_state))
-               return ERR_CAST(priv_state);
+       if (!priv_state)
+               return ERR_PTR(-EINVAL);
 
        return to_vc4_hvs_state(priv_state);
 }
@@ -210,8 +210,8 @@ vc4_hvs_get_old_global_state(struct drm_atomic_state *state)
        struct drm_private_state *priv_state;
 
        priv_state = drm_atomic_get_old_private_obj_state(state, &vc4->hvs_channels);
-       if (IS_ERR(priv_state))
-               return ERR_CAST(priv_state);
+       if (!priv_state)
+               return ERR_PTR(-EINVAL);
 
        return to_vc4_hvs_state(priv_state);
 }