[PATCH 12/12] drm: make sysfs device always available for minors
Daniel Vetter
daniel at ffwll.ch
Thu Jul 24 03:36:06 PDT 2014
On Wed, Jul 23, 2014 at 05:26:47PM +0200, David Herrmann wrote:
> 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>
Some diff got confused with this one. One comment below, but this is
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> ---
> 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);
Not sure about the device model, but could we just embedded the kdev into
struct drm_minor? Separate patch ofc.
> +
> + 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
>
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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