[PATCH 12/12] drm: make sysfs device always available for minors
David Herrmann
dh.herrmann at gmail.com
Wed Jul 23 08:26:47 PDT 2014
For each minor we allocate a sysfs device as minor->kdev. Currently, this
is allocated and registered in drm_minor_register(). This makes it
impossible to add sysfs-attributes to the device before it is registered.
Therefore, they are not added atomically, nor can we move device_add()
*after* ->load() is called.
This patch makes minor->kdev available early, but only adds the device
during minor-registration.
Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
---
drivers/gpu/drm/drm_stub.c | 22 ++++++++---
drivers/gpu/drm/drm_sysfs.c | 90 +++++++++++++++++++--------------------------
include/drm/drmP.h | 3 +-
3 files changed, 54 insertions(+), 61 deletions(-)
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index 8b24db5..09c6bfb 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -281,9 +281,19 @@ static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
minor->index = r;
+ minor->kdev = drm_sysfs_minor_alloc(minor);
+ if (IS_ERR(minor->kdev)) {
+ r = PTR_ERR(minor->kdev);
+ goto err_index;
+ }
+
*drm_minor_get_slot(dev, type) = minor;
return 0;
+err_index:
+ spin_lock_irqsave(&drm_minor_lock, flags);
+ idr_remove(&drm_minors_idr, minor->index);
+ spin_unlock_irqrestore(&drm_minor_lock, flags);
err_free:
kfree(minor);
return r;
@@ -300,6 +310,7 @@ static void drm_minor_free(struct drm_device *dev, unsigned int type)
return;
drm_mode_group_destroy(&minor->mode_group);
+ put_device(minor->kdev);
spin_lock_irqsave(&drm_minor_lock, flags);
idr_remove(&drm_minors_idr, minor->index);
@@ -327,11 +338,9 @@ static int drm_minor_register(struct drm_device *dev, unsigned int type)
return ret;
}
- ret = drm_sysfs_device_add(minor);
- if (ret) {
- DRM_ERROR("DRM: Error sysfs_device_add.\n");
+ ret = device_add(minor->kdev);
+ if (ret)
goto err_debugfs;
- }
/* replace NULL with @minor so lookups will succeed from now on */
spin_lock_irqsave(&drm_minor_lock, flags);
@@ -352,7 +361,7 @@ static void drm_minor_unregister(struct drm_device *dev, unsigned int type)
unsigned long flags;
minor = *drm_minor_get_slot(dev, type);
- if (!minor || !minor->kdev)
+ if (!minor || !device_is_registered(minor->kdev))
return;
/* replace @minor with NULL so lookups will fail from now on */
@@ -360,8 +369,9 @@ static void drm_minor_unregister(struct drm_device *dev, unsigned int type)
idr_replace(&drm_minors_idr, NULL, minor->index);
spin_unlock_irqrestore(&drm_minor_lock, flags);
+ device_del(minor->kdev);
+ dev_set_drvdata(minor->kdev, NULL); /* safety belt */
drm_debugfs_cleanup(minor);
- drm_sysfs_device_remove(minor);
}
/**
diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 7827dad..ab1a5f6 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -493,71 +493,55 @@ static void drm_sysfs_release(struct device *dev)
}
/**
- * drm_sysfs_device_add - adds a class device to sysfs for a character driver
- * @dev: DRM device to be added
- * @head: DRM head in question
+ * drm_sysfs_minor_alloc() - Allocate sysfs device for given minor
+ * @minor: minor to allocate sysfs device for
*
- * Add a DRM device to the DRM's device model class. We use @dev's PCI device
- * as the parent for the Linux device, and make sure it has a file containing
- * the driver we're using (for userspace compatibility).
+ * This allocates a new sysfs device for @minor and returns it. The device is
+ * not registered nor linked. The caller has to use device_add() and
+ * device_del() to register and unregister it.
+ *
+ * Note that dev_get_drvdata() on the new device will return the minor.
+ * However, the device does not hold a ref-count to the minor nor to the
+ * underlying drm_device. This is unproblematic as long as you access the
+ * private data only in sysfs callbacks. device_del() disables those
+ * synchronously, so they cannot be called after you cleanup a minor.
*/
-int drm_sysfs_device_add(struct drm_minor *minor)
+struct device *drm_sysfs_minor_alloc(struct drm_minor *minor)
{
- char *minor_str;
+ const char *minor_str;
+ struct device *kdev;
int r;
if (minor->type == DRM_MINOR_CONTROL)
minor_str = "controlD%d";
- else if (minor->type == DRM_MINOR_RENDER)
- minor_str = "renderD%d";
- else
- minor_str = "card%d";
-
- minor->kdev = kzalloc(sizeof(*minor->kdev), GFP_KERNEL);
- if (!minor->kdev) {
- r = -ENOMEM;
- goto error;
- }
-
- device_initialize(minor->kdev);
- minor->kdev->devt = MKDEV(DRM_MAJOR, minor->index);
- minor->kdev->class = drm_class;
- minor->kdev->type = &drm_sysfs_device_minor;
- minor->kdev->parent = minor->dev->dev;
- minor->kdev->release = drm_sysfs_release;
- dev_set_drvdata(minor->kdev, minor);
-
- r = dev_set_name(minor->kdev, minor_str, minor->index);
+ else if (minor->type == DRM_MINOR_RENDER)
+ minor_str = "renderD%d";
+ else
+ minor_str = "card%d";
+
+ kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
+ if (!kdev)
+ return ERR_PTR(-ENOMEM);
+
+ device_initialize(kdev);
+ kdev->devt = MKDEV(DRM_MAJOR, minor->index);
+ kdev->class = drm_class;
+ kdev->type = &drm_sysfs_device_minor;
+ kdev->parent = minor->dev->dev;
+ kdev->release = drm_sysfs_release;
+ dev_set_drvdata(kdev, minor);
+
+ r = dev_set_name(kdev, minor_str, minor->index);
if (r < 0)
- goto error;
-
- r = device_add(minor->kdev);
- if (r < 0)
- goto error;
-
- return 0;
+ goto err_free;
-error:
- DRM_ERROR("device create failed %d\n", r);
- put_device(minor->kdev);
- return r;
-}
+ return kdev;
-/**
- * drm_sysfs_device_remove - remove DRM device
- * @dev: DRM device to remove
- *
- * This call unregisters and cleans up a class device that was created with a
- * call to drm_sysfs_device_add()
- */
-void drm_sysfs_device_remove(struct drm_minor *minor)
-{
- if (minor->kdev)
- device_unregister(minor->kdev);
- minor->kdev = NULL;
+err_free:
+ put_device(kdev);
+ return ERR_PTR(r);
}
-
/**
* drm_class_device_register - Register a struct device in the drm class.
*
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 17dd67a..d28d337 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1492,9 +1492,8 @@ extern int drm_pci_set_unique(struct drm_device *dev,
struct drm_sysfs_class;
extern struct class *drm_sysfs_create(struct module *owner, char *name);
extern void drm_sysfs_destroy(void);
-extern int drm_sysfs_device_add(struct drm_minor *minor);
+extern struct device *drm_sysfs_minor_alloc(struct drm_minor *minor);
extern void drm_sysfs_hotplug_event(struct drm_device *dev);
-extern void drm_sysfs_device_remove(struct drm_minor *minor);
extern int drm_sysfs_connector_add(struct drm_connector *connector);
extern void drm_sysfs_connector_remove(struct drm_connector *connector);
--
2.0.2
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