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drm: make minor->index available early
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Instead of allocating the minor-index during registration, we now do this
during allocation. This way, debug-messages between minor-allocation and
minor-registration will now use the correct minor instead of 0. Same is
done for unregistration vs. free, so debug-messages between
device-shutdown and device-destruction show proper indices.

Even though minor-indices are allocated early, we don't enable minor
lookup early. Instead, we keep the entry set to NULL and replace it during
registration / unregistration. This way, the index is allocated but lookup
only works if registered.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
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David Herrmann committed Aug 5, 2014
1 parent ec8f112 commit f1b8596
Showing 1 changed file with 46 additions and 38 deletions.
84 changes: 46 additions & 38 deletions drivers/gpu/drm/drm_stub.c
Original file line number Diff line number Diff line change
@@ -256,6 +256,8 @@ static struct drm_minor **drm_minor_get_slot(struct drm_device *dev,
static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
{
struct drm_minor *minor;
unsigned long flags;
int r;

minor = kzalloc(sizeof(*minor), GFP_KERNEL);
if (!minor)
@@ -264,77 +266,83 @@ static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
minor->type = type;
minor->dev = dev;

idr_preload(GFP_KERNEL);
spin_lock_irqsave(&drm_minor_lock, flags);
r = idr_alloc(&drm_minors_idr,
NULL,
64 * type,
64 * (type + 1),
GFP_NOWAIT);
spin_unlock_irqrestore(&drm_minor_lock, flags);
idr_preload_end();

if (r < 0)
goto err_free;

minor->index = r;

*drm_minor_get_slot(dev, type) = minor;
return 0;

err_free:
kfree(minor);
return r;
}

static void drm_minor_free(struct drm_device *dev, unsigned int type)
{
struct drm_minor **slot;
struct drm_minor **slot, *minor;
unsigned long flags;

slot = drm_minor_get_slot(dev, type);
if (*slot) {
drm_mode_group_destroy(&(*slot)->mode_group);
kfree(*slot);
*slot = NULL;
}
minor = *slot;
if (!minor)
return;

drm_mode_group_destroy(&minor->mode_group);

spin_lock_irqsave(&drm_minor_lock, flags);
idr_remove(&drm_minors_idr, minor->index);
spin_unlock_irqrestore(&drm_minor_lock, flags);

kfree(minor);
*slot = NULL;
}

static int drm_minor_register(struct drm_device *dev, unsigned int type)
{
struct drm_minor *new_minor;
struct drm_minor *minor;
unsigned long flags;
int ret;
int minor_id;

DRM_DEBUG("\n");

new_minor = *drm_minor_get_slot(dev, type);
if (!new_minor)
minor = *drm_minor_get_slot(dev, type);
if (!minor)
return 0;

idr_preload(GFP_KERNEL);
spin_lock_irqsave(&drm_minor_lock, flags);
minor_id = idr_alloc(&drm_minors_idr,
NULL,
64 * type,
64 * (type + 1),
GFP_NOWAIT);
spin_unlock_irqrestore(&drm_minor_lock, flags);
idr_preload_end();

if (minor_id < 0)
return minor_id;

new_minor->index = minor_id;

ret = drm_debugfs_init(new_minor, minor_id, drm_debugfs_root);
ret = drm_debugfs_init(minor, minor->index, drm_debugfs_root);
if (ret) {
DRM_ERROR("DRM: Failed to initialize /sys/kernel/debug/dri.\n");
goto err_id;
return ret;
}

ret = drm_sysfs_device_add(new_minor);
ret = drm_sysfs_device_add(minor);
if (ret) {
DRM_ERROR("DRM: Error sysfs_device_add.\n");
goto err_debugfs;
}

/* replace NULL with @minor so lookups will succeed from now on */
spin_lock_irqsave(&drm_minor_lock, flags);
idr_replace(&drm_minors_idr, new_minor, new_minor->index);
idr_replace(&drm_minors_idr, minor, minor->index);
spin_unlock_irqrestore(&drm_minor_lock, flags);

DRM_DEBUG("new minor assigned %d\n", minor_id);
DRM_DEBUG("new minor registered %d\n", minor->index);
return 0;

err_debugfs:
drm_debugfs_cleanup(new_minor);
err_id:
spin_lock_irqsave(&drm_minor_lock, flags);
idr_remove(&drm_minors_idr, minor_id);
spin_unlock_irqrestore(&drm_minor_lock, flags);
new_minor->index = 0;
drm_debugfs_cleanup(minor);
return ret;
}

@@ -347,10 +355,10 @@ static void drm_minor_unregister(struct drm_device *dev, unsigned int type)
if (!minor || !minor->kdev)
return;

/* replace @minor with NULL so lookups will fail from now on */
spin_lock_irqsave(&drm_minor_lock, flags);
idr_remove(&drm_minors_idr, minor->index);
idr_replace(&drm_minors_idr, NULL, minor->index);
spin_unlock_irqrestore(&drm_minor_lock, flags);
minor->index = 0;

drm_debugfs_cleanup(minor);
drm_sysfs_device_remove(minor);

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