> 2025年1月9日 00:04，Mario Limonciello <mario.limoncie...@amd.com> 写道：
>
> On 1/8/2025 02:56, Jiang Liu wrote:
>> Introduce new interface amdgpu_xcp_drm_dev_free() to free a specific
>> drm_device crreated by amdgpu_xcp_drm_dev_alloc(), which will be used
>> to do error recovery.
>> Signed-off-by: Jiang Liu <ge...@linux.alibaba.com>
>> ---
>> drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c | 76 +++++++++++++++++----
>> drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h | 1 +
>> 2 files changed, 63 insertions(+), 14 deletions(-)
>> diff --git a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
>> b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
>> index faed84172dd4..fc92b5fe1040 100644
>> --- a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
>> +++ b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
>> @@ -45,21 +45,32 @@ static const struct drm_driver amdgpu_xcp_driver = {
>> static int8_t pdev_num;
>> static struct xcp_device *xcp_dev[MAX_XCP_PLATFORM_DEVICE];
>> +static DEFINE_MUTEX(xcp_mutex);
>> int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev)
>> {
>> struct platform_device *pdev;
>> struct xcp_device *pxcp_dev;
>> char dev_name[20];
>> - int ret;
>> + int ret, index;
>> - if (pdev_num >= MAX_XCP_PLATFORM_DEVICE)
>> - return -ENODEV;
>> + mutex_lock(&xcp_mutex);
>
> For "new" code what do you think about about using scoped guards like
> guard(mutex) instead of lock; goto label; unlock pattern?
>
> I think it can generally keep the code cleaner, but you need to be careful
> because if you still need "other" goto cleanup patterns you can
> unintentionally break the compiled output.
Thanks for introducing this new utility, which makes me feel like writing rust
code:)
>
>> + if (pdev_num >= MAX_XCP_PLATFORM_DEVICE) {
>> + ret = -ENODEV;
>> + goto out_unlock;
>> + }
>> +
>> + for (index = 0; index < MAX_XCP_PLATFORM_DEVICE; index++) {
>> + if (!xcp_dev[index])
>> + break;
>> + }
>> - snprintf(dev_name, sizeof(dev_name), "amdgpu_xcp_%d", pdev_num);
>> + snprintf(dev_name, sizeof(dev_name), "amdgpu_xcp_%d", index);
>> pdev = platform_device_register_simple(dev_name, -1, NULL, 0);
>> - if (IS_ERR(pdev))
>> - return PTR_ERR(pdev);
>> + if (IS_ERR(pdev)) {
>> + ret = PTR_ERR(pdev);
>> + goto out_unregister;
>
> Er, if you fail to register why would you unregister? I think in this case
> with the current code you would 'goto out_unlock' instead.
>
> The design pattern you might have been following was from platform drivers
> that do this, which is different:
>
> platform_driver_register()
> foo = platform_device_register_simple()
> if (IS_ERR(foo))
> platform_driver_unregister()
> return 0;
Will fix it in next version.
>
>> + }
>> if (!devres_open_group(&pdev->dev, NULL, GFP_KERNEL)) {
>> ret = -ENOMEM;
>> @@ -72,10 +83,11 @@ int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev)
>> goto out_devres;
>> }
>> - xcp_dev[pdev_num] = pxcp_dev;
>> - xcp_dev[pdev_num]->pdev = pdev;
>> + xcp_dev[index] = pxcp_dev;
>> + xcp_dev[index]->pdev = pdev;
>> *ddev = &pxcp_dev->drm;
>> pdev_num++;
>> + mutex_unlock(&xcp_mutex);
>> return 0;
>> @@ -83,21 +95,57 @@ int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev)
>> devres_release_group(&pdev->dev, NULL);
>> out_unregister:
>> platform_device_unregister(pdev);
>> +out_unlock:
>> + mutex_unlock(&xcp_mutex);
>> return ret;
>> }
>> EXPORT_SYMBOL(amdgpu_xcp_drm_dev_alloc);
>> +static void amdgpu_xcp_drm_dev_destroy(int index)
>> +{
>> + struct platform_device *pdev;
>> +
>> + pdev = xcp_dev[index]->pdev;
>> + devres_release_group(&pdev->dev, NULL);
>> + platform_device_unregister(pdev);
>> + xcp_dev[index] = NULL;
>> + pdev_num--;
>> +}
>> +
>> +void amdgpu_xcp_drm_dev_free(struct drm_device *ddev)
>> +{
>> + int index;
>> + struct xcp_device *pxcp_dev;
>> +
>> + if (ddev == NULL)
>> + return;
>> +
>> + pxcp_dev = container_of(ddev, struct xcp_device, drm);
>> +
>> + mutex_lock(&xcp_mutex);
>
> I think this is a good case for a guard(mutex) instead.
>
>> + for (index = 0; index < MAX_XCP_PLATFORM_DEVICE; index++) {
>> + if (xcp_dev[index] == pxcp_dev) {
>> + amdgpu_xcp_drm_dev_destroy(index);
>> + break;
>> + }
>> + }
>> + mutex_unlock(&xcp_mutex);
>> +}
>> +EXPORT_SYMBOL(amdgpu_xcp_drm_dev_free);
>> +
>> void amdgpu_xcp_drv_release(void)
>> {
>> - for (--pdev_num; pdev_num >= 0; --pdev_num) {
>> - struct platform_device *pdev = xcp_dev[pdev_num]->pdev;
>> + int index;
>> - devres_release_group(&pdev->dev, NULL);
>> - platform_device_unregister(pdev);
>> - xcp_dev[pdev_num] = NULL;
>> + mutex_lock(&xcp_mutex);
>
> Another good case for guard(mutex)
>
>> + for (index = 0; index < MAX_XCP_PLATFORM_DEVICE; index++) {
>> + if (xcp_dev[index]) {
>> + amdgpu_xcp_drm_dev_destroy(index);
>> + }
>> }
>> - pdev_num = 0;
>> + WARN_ON(pdev_num != 0);
>> + mutex_unlock(&xcp_mutex);
>> }
>> EXPORT_SYMBOL(amdgpu_xcp_drv_release);
>> diff --git a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
>> b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
>> index c1c4b679bf95..580a1602c8e3 100644
>> --- a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
>> +++ b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
>> @@ -25,5 +25,6 @@
>> #define _AMDGPU_XCP_DRV_H_
>> int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev);
>> +void amdgpu_xcp_drm_dev_free(struct drm_device *ddev);
>> void amdgpu_xcp_drv_release(void);
>> #endif /* _AMDGPU_XCP_DRV_H_ */
