Re: [PATCH] drm: Remove the deprecated drm_put_dev() function

From: Sui Jingfeng
Date: Tue Jun 27 2023 - 05:05:18 EST


Hi,

On 2023/6/26 15:48, Jani Nikula wrote:
On Sun, 25 Jun 2023, Sui Jingfeng <suijingfeng@xxxxxxxxxxx> wrote:
As this function can be replaced with drm_dev_unregister() + drm_dev_put(),
it is already marked as deprecated, so remove it. No functional change.

Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
---
drivers/gpu/drm/drm_drv.c | 28 ----------------------------
drivers/gpu/drm/drm_pci.c | 3 ++-
drivers/gpu/drm/radeon/radeon_drv.c | 3 ++-
include/drm/drm_drv.h | 1 -
4 files changed, 4 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 12687dd9e1ac..5057307fe22a 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -406,34 +406,6 @@ void drm_minor_release(struct drm_minor *minor)
* possibly leaving the hardware enabled.
*/
-/**
- * drm_put_dev - Unregister and release a DRM device
- * @dev: DRM device
- *
- * Called at module unload time or when a PCI device is unplugged.
- *
- * Cleans up all DRM device, calling drm_lastclose().
- *
- * Note: Use of this function is deprecated. It will eventually go away
- * completely. Please use drm_dev_unregister() and drm_dev_put() explicitly
- * instead to make sure that the device isn't userspace accessible any more
- * while teardown is in progress, ensuring that userspace can't access an
- * inconsistent state.
The last sentence is the crucial one. While the patch has no functional
changes,

But my patch help to save a useless check(if (!dev))

on where we found the check is not necessary.

```

- if (!dev) {
- DRM_ERROR("cleanup called no dev\n");
- return;
- }

```


I believe the goal never was to just mechanically replace one
call with the two.

The DRM core lose nothing, just a function wrapper.

Instead, this is probably a good chance to migrate the burden to the driver side.

I think the device driver(drm/radeon, for example) have better understanding

about how to ensure that userspace can't access an inconsistent state than the DRM core.


BR,
Jani.


- */
-void drm_put_dev(struct drm_device *dev)
-{
- DRM_DEBUG("\n");
-
- if (!dev) {
- DRM_ERROR("cleanup called no dev\n");
- return;
- }
-
- drm_dev_unregister(dev);
- drm_dev_put(dev);
-}
-EXPORT_SYMBOL(drm_put_dev);
-
/**
* drm_dev_enter - Enter device critical section
* @dev: DRM device
diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 39d35fc3a43b..b3a68a92eaa6 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -257,7 +257,8 @@ void drm_legacy_pci_exit(const struct drm_driver *driver,
legacy_dev_list) {
if (dev->driver == driver) {
list_del(&dev->legacy_dev_list);
- drm_put_dev(dev);
+ drm_dev_unregister(dev);
+ drm_dev_put(dev);
}
}
mutex_unlock(&legacy_dev_list_lock);
diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index e4374814f0ef..a4955ae10659 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -357,7 +357,8 @@ radeon_pci_remove(struct pci_dev *pdev)
{
struct drm_device *dev = pci_get_drvdata(pdev);
- drm_put_dev(dev);
+ drm_dev_unregister(dev);
+ drm_dev_put(dev);
}
static void
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 89e2706cac56..289c97b12e82 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -511,7 +511,6 @@ void drm_dev_unregister(struct drm_device *dev);
void drm_dev_get(struct drm_device *dev);
void drm_dev_put(struct drm_device *dev);
-void drm_put_dev(struct drm_device *dev);
bool drm_dev_enter(struct drm_device *dev, int *idx);
void drm_dev_exit(int idx);
void drm_dev_unplug(struct drm_device *dev);

--
Jingfeng