[PATCH v5 5/6] drm/msm/dpu: fix error handling in dpu_rm_init

[Dmitry Baryshkov]

On 14/02/2022 22:15, Abhinav Kumar wrote:
> 
> 
> On 1/21/2022 1:06 PM, Dmitry Baryshkov wrote:
>> Using IS_ERR_OR_NULL() together with PTR_ERR() is a typical mistake. If
>> the value is NULL, then the function will return 0 instead of a proper
>> return code. Moreover none of dpu_hw_*_init() functions can return NULL.
>> So, replace all dpu_rm_init()'s IS_ERR_OR_NULL() calls with IS_ERR().
>>
> Can you please give an example of a case where dpu_hw_*_init() can 
> return NULL?
> 
> All dpu_hw_*_init() functions are only called if the corresponding
> hw*_counts are valid. So I would like to understand this.
> 
> Now, if NULL is treated as a non-error case, should we atleast print
> a message indicating so?

- No dpu_hw_*init() can return NULL

- If at some point any of these functions returns NULL, it will cause a 
premature dpu_rm_init() termination with the success (=0) status, 
leaving parts of RM uninitialized.

Thus I'm replacing IS_ERR_OR_NULL with IS_ERR()

> 
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 12 ++++++------
>>   1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
>> index 96554e962e38..7497538adae1 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
>> @@ -109,7 +109,7 @@ int dpu_rm_init(struct dpu_rm *rm,
>>               continue;
>>           }
>>           hw = dpu_hw_lm_init(lm->id, mmio, cat);
>> -        if (IS_ERR_OR_NULL(hw)) {
>> +        if (IS_ERR(hw)) {
>>               rc = PTR_ERR(hw);
>>               DPU_ERROR("failed lm object creation: err %d\n", rc);
>>               goto fail;
>> @@ -126,7 +126,7 @@ int dpu_rm_init(struct dpu_rm *rm,
>>               continue;
>>           }
>>           hw = dpu_hw_merge_3d_init(merge_3d->id, mmio, cat);
>> -        if (IS_ERR_OR_NULL(hw)) {
>> +        if (IS_ERR(hw)) {
>>               rc = PTR_ERR(hw);
>>               DPU_ERROR("failed merge_3d object creation: err %d\n",
>>                   rc);
>> @@ -144,7 +144,7 @@ int dpu_rm_init(struct dpu_rm *rm,
>>               continue;
>>           }
>>           hw = dpu_hw_pingpong_init(pp->id, mmio, cat);
>> -        if (IS_ERR_OR_NULL(hw)) {
>> +        if (IS_ERR(hw)) {
>>               rc = PTR_ERR(hw);
>>               DPU_ERROR("failed pingpong object creation: err %d\n",
>>                   rc);
>> @@ -168,7 +168,7 @@ int dpu_rm_init(struct dpu_rm *rm,
>>               continue;
>>           }
>>           hw = dpu_hw_intf_init(intf->id, mmio, cat);
>> -        if (IS_ERR_OR_NULL(hw)) {
>> +        if (IS_ERR(hw)) {
>>               rc = PTR_ERR(hw);
>>               DPU_ERROR("failed intf object creation: err %d\n", rc);
>>               goto fail;
>> @@ -185,7 +185,7 @@ int dpu_rm_init(struct dpu_rm *rm,
>>               continue;
>>           }
>>           hw = dpu_hw_ctl_init(ctl->id, mmio, cat);
>> -        if (IS_ERR_OR_NULL(hw)) {
>> +        if (IS_ERR(hw)) {
>>               rc = PTR_ERR(hw);
>>               DPU_ERROR("failed ctl object creation: err %d\n", rc);
>>               goto fail;
>> @@ -202,7 +202,7 @@ int dpu_rm_init(struct dpu_rm *rm,
>>               continue;
>>           }
>>           hw = dpu_hw_dspp_init(dspp->id, mmio, cat);
>> -        if (IS_ERR_OR_NULL(hw)) {
>> +        if (IS_ERR(hw)) {
>>               rc = PTR_ERR(hw);
>>               DPU_ERROR("failed dspp object creation: err %d\n", rc);
>>               goto fail;


-- 
With best wishes
Dmitry