[drm-misc:drm-misc-next 2/3] drivers/gpu/drm/loongson/lsdc_plane.c:199 lsdc_cursor_plane_atomic_async_check() warn: variable dereferenced before check 'state' (see line 180)
suijingfeng
suijingfeng at loongson.cn
Mon Jul 10 07:36:24 UTC 2023
Hi,
On 2023/7/10 15:19, Thomas Zimmermann wrote:
> Hi
>
> Am 10.07.23 um 09:02 schrieb suijingfeng:
>> Hi,
>>
>>
>> Thanks for testing,
>>
>> What do you means about tell me this?
>>
>> I means that would you like to help fixing this warning?
>
> The code in drm_atomic_get_new_plane_state() dereferences the state
> parameter. Later in your function, you test for state to be non-NULL.
> That's what the warning is about.
>
> You should be able to silence this warning by removing the state test
> from your function (and also delete that else branch). There should
> always be an atomic state present and the atomic-check callbacks
> should not be called without a state. If not, the driver most likely
> failed to initialize correctly.
>
Yes, I will create a patch to fix this warning before tonight.
The driver works very well, it never print with kernel 'cmd drm.debug=0x02'.
I just feel interesting, thanks.
> Best regards
> Thomas
>
>>
>> Or otherwise, I will fix this someday.
>>
>>
>> On 2023/7/10 14:29, Dan Carpenter wrote:
>>> tree: git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
>>> head: 8d1077cf2e43b15fefd76ebec2b71541eb27ef2c
>>> commit: f39db26c54281da6a785259498ca74b5e470476f [2/3] drm: Add kms
>>> driver for loongson display controller
>>> config: i386-randconfig-m021-20230710
>>> (https://download.01.org/0day-ci/archive/20230710/202307100423.rV7D05Uq-lkp@intel.com/config)
>>> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
>>> reproduce:
>>> (https://download.01.org/0day-ci/archive/20230710/202307100423.rV7D05Uq-lkp@intel.com/reproduce)
>>>
>>> If you fix the issue in a separate patch/commit (i.e. not just a new
>>> version of
>>> the same patch/commit), kindly add following tags
>>> | Reported-by: kernel test robot <lkp at intel.com>
>>> | Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
>>> | Closes:
>>> https://lore.kernel.org/r/202307100423.rV7D05Uq-lkp@intel.com/
>>>
>>> smatch warnings:
>>> drivers/gpu/drm/loongson/lsdc_plane.c:199
>>> lsdc_cursor_plane_atomic_async_check() warn: variable dereferenced
>>> before check 'state' (see line 180)
>>>
>>> vim +/state +199 drivers/gpu/drm/loongson/lsdc_plane.c
>>>
>>> f39db26c54281d Sui Jingfeng 2023-06-15 174 static int
>>> lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
>>> f39db26c54281d Sui Jingfeng 2023-06-15 175
>>> struct drm_atomic_state *state)
>>> f39db26c54281d Sui Jingfeng 2023-06-15 176 {
>>> f39db26c54281d Sui Jingfeng 2023-06-15 177 struct
>>> drm_plane_state *new_state;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 178 struct
>>> drm_crtc_state *crtc_state;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 179
>>> f39db26c54281d Sui Jingfeng 2023-06-15 @180 new_state =
>>> drm_atomic_get_new_plane_state(state, plane);
>>> ^^^^^
>>> state is dereferenced inside this function
>>>
>>> f39db26c54281d Sui Jingfeng 2023-06-15 181
>>> f39db26c54281d Sui Jingfeng 2023-06-15 182 if (!plane->state
>>> || !plane->state->fb) {
>>> f39db26c54281d Sui Jingfeng 2023-06-15 183 drm_dbg(plane->dev, "%s:
>>> state is NULL\n", plane->name);
>>> f39db26c54281d Sui Jingfeng 2023-06-15 184 return -EINVAL;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 185 }
>>> f39db26c54281d Sui Jingfeng 2023-06-15 186
>>> f39db26c54281d Sui Jingfeng 2023-06-15 187 if
>>> (new_state->crtc_w != new_state->crtc_h) {
>>> f39db26c54281d Sui Jingfeng 2023-06-15 188 drm_dbg(plane->dev,
>>> "unsupported cursor size: %ux%u\n",
>>> f39db26c54281d Sui Jingfeng 2023-06-15 189 new_state->crtc_w,
>>> new_state->crtc_h);
>>> f39db26c54281d Sui Jingfeng 2023-06-15 190 return -EINVAL;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 191 }
>>> f39db26c54281d Sui Jingfeng 2023-06-15 192
>>> f39db26c54281d Sui Jingfeng 2023-06-15 193 if
>>> (new_state->crtc_w != 64 && new_state->crtc_w != 32) {
>>> f39db26c54281d Sui Jingfeng 2023-06-15 194 drm_dbg(plane->dev,
>>> "unsupported cursor size: %ux%u\n",
>>> f39db26c54281d Sui Jingfeng 2023-06-15 195 new_state->crtc_w,
>>> new_state->crtc_h);
>>> f39db26c54281d Sui Jingfeng 2023-06-15 196 return -EINVAL;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 197 }
>>> f39db26c54281d Sui Jingfeng 2023-06-15 198
>>> f39db26c54281d Sui Jingfeng 2023-06-15 @199 if (state) {
>>> ^^^^^
>>> Checked too late
>>>
>>> f39db26c54281d Sui Jingfeng 2023-06-15 200 crtc_state =
>>> drm_atomic_get_existing_crtc_state(state, new_state->crtc);
>>> f39db26c54281d Sui Jingfeng 2023-06-15 201 } else {
>>> f39db26c54281d Sui Jingfeng 2023-06-15 202 crtc_state =
>>> plane->crtc->state;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 203 drm_dbg(plane->dev, "%s:
>>> atomic state is NULL\n", plane->name);
>>> f39db26c54281d Sui Jingfeng 2023-06-15 204 }
>>> f39db26c54281d Sui Jingfeng 2023-06-15 205
>>> f39db26c54281d Sui Jingfeng 2023-06-15 206 if
>>> (!crtc_state->active)
>>> f39db26c54281d Sui Jingfeng 2023-06-15 207 return -EINVAL;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 208
>>> f39db26c54281d Sui Jingfeng 2023-06-15 209 if
>>> (plane->state->crtc != new_state->crtc ||
>>> f39db26c54281d Sui Jingfeng 2023-06-15 210 plane->state->src_w !=
>>> new_state->src_w ||
>>> f39db26c54281d Sui Jingfeng 2023-06-15 211 plane->state->src_h !=
>>> new_state->src_h ||
>>> f39db26c54281d Sui Jingfeng 2023-06-15 212 plane->state->crtc_w !=
>>> new_state->crtc_w ||
>>> f39db26c54281d Sui Jingfeng 2023-06-15 213 plane->state->crtc_h !=
>>> new_state->crtc_h)
>>> f39db26c54281d Sui Jingfeng 2023-06-15 214 return -EINVAL;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 215
>>> f39db26c54281d Sui Jingfeng 2023-06-15 216 if
>>> (new_state->visible != plane->state->visible)
>>> f39db26c54281d Sui Jingfeng 2023-06-15 217 return -EINVAL;
>>> f39db26c54281d Sui Jingfeng 2023-06-15 218
>>> f39db26c54281d Sui Jingfeng 2023-06-15 219 return
>>> drm_atomic_helper_check_plane_state(plane->state,
>>> f39db26c54281d Sui Jingfeng 2023-06-15
>>> 220 crtc_state,
>>> f39db26c54281d Sui Jingfeng 2023-06-15
>>> 221 DRM_PLANE_NO_SCALING,
>>> f39db26c54281d Sui Jingfeng 2023-06-15
>>> 222 DRM_PLANE_NO_SCALING,
>>> f39db26c54281d Sui Jingfeng 2023-06-15
>>> 223 true, true);
>>> f39db26c54281d Sui Jingfeng 2023-06-15 224 }
>>>
>>
>
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