[PATCH v4] drm/ioctl: Add a ioctl to label GEM objects

[Rohan Garg <rohan.garg@collabora.com>]

DRM_IOCTL_DUMB_SET_LABEL lets you label GEM objects, making it
easier to debug issues in userspace applications.

Changes in v2:
  - Hoist the IOCTL up into the drm_driver framework

Changes in v3:
  - Introduce a drm_gem_set_label for drivers to use internally
    in order to label a GEM object
  - Hoist string copying up into the IOCTL
  - Fix documentation
  - Move actual gem labeling into drm_gem_adopt_label

Changes in v4:
  - Refactor IOCTL call to only perform string duplication and move
    all gem lookup logic into GEM specific call

Signed-off-by: Rohan Garg <rohan.garg@collabora.com>
---
 drivers/gpu/drm/drm_gem.c      | 70 ++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_internal.h |  8 ++++
 drivers/gpu/drm/drm_ioctl.c    |  1 +
 include/drm/drm_drv.h          | 16 ++++++++
 include/drm/drm_gem.h          |  7 ++++
 include/uapi/drm/drm.h         | 20 ++++++++++
 6 files changed, 122 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 6854f5867d51..0fa4609b2817 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -941,6 +941,71 @@ drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 	idr_destroy(&file_private->object_idr);
 }
 
+int drm_dumb_set_label_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *file_priv)
+{
+	char *label;
+	struct drm_dumb_set_label_object *args = data;
+	int ret = 0;
+
+	if (!args->len || !args->name)
+		return -EINVAL;
+
+	if (!dev->driver->label)
+		return -EOPNOTSUPP;
+
+	label = strndup_user(u64_to_user_ptr(args->name), args->len);
+
+	if (IS_ERR(label)) {
+		ret = PTR_ERR(label);
+		goto err;
+	}
+
+	ret = dev->driver->label(dev, file_priv, args->handle, label);
+
+err:
+	kfree(label);
+	return ret;
+}
+
+int drm_gem_set_label(struct drm_device *dev,
+		       struct drm_file *file_priv,
+			   uint32_t handle,
+			   const char *label)
+{
+	struct drm_gem_object *gem_obj;
+	int ret = 0;
+
+	gem_obj = drm_gem_object_lookup(file_priv, handle);
+	if (!gem_obj) {
+		DRM_DEBUG("Failed to look up GEM BO %d\n", handle);
+		ret = -ENOENT;
+		goto err;
+	}
+	drm_gem_adopt_label(gem_obj, label);
+
+err:
+	drm_gem_object_put_unlocked(gem_obj);
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_set_label);
+
+void drm_gem_adopt_label(struct drm_gem_object *gem_obj, const char *label)
+{
+	char *adopted_label = NULL;
+
+	if (label)
+		adopted_label = kstrdup(label, GFP_KERNEL);
+
+	if (gem_obj->label) {
+		kfree(gem_obj->label);
+		gem_obj->label = NULL;
+	}
+
+	gem_obj->label = adopted_label;
+}
+EXPORT_SYMBOL(drm_gem_adopt_label);
+
 /**
  * drm_gem_object_release - release GEM buffer object resources
  * @obj: GEM buffer object
@@ -958,6 +1023,11 @@ drm_gem_object_release(struct drm_gem_object *obj)
 
 	dma_resv_fini(&obj->_resv);
 	drm_gem_free_mmap_offset(obj);
+
+	if (obj->label) {
+		kfree(obj->label);
+		obj->label = NULL;
+	}
 }
 EXPORT_SYMBOL(drm_gem_object_release);
 
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 51a2055c8f18..cbc3f7b7fb9b 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -137,6 +137,14 @@ int drm_gem_pin(struct drm_gem_object *obj);
 void drm_gem_unpin(struct drm_gem_object *obj);
 void *drm_gem_vmap(struct drm_gem_object *obj);
 void drm_gem_vunmap(struct drm_gem_object *obj, void *vaddr);
+int drm_dumb_set_label_ioctl(struct drm_device *dev,
+			void *data,
+			struct drm_file *file_priv);
+int drm_gem_set_label(struct drm_device *dev,
+			struct drm_file *file_priv,
+			uint32_t handle,
+			const char *label);
+void drm_gem_adopt_label(struct drm_gem_object *gem_obj, const char *label);
 
 /* drm_debugfs.c drm_debugfs_crc.c */
 #if defined(CONFIG_DEBUG_FS)
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index fcd728d7cf72..f34e1571d70f 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -714,6 +714,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_LIST_LESSEES, drm_mode_list_lessees_ioctl, DRM_MASTER),
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_GET_LEASE, drm_mode_get_lease_ioctl, DRM_MASTER),
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_REVOKE_LEASE, drm_mode_revoke_lease_ioctl, DRM_MASTER),
+	DRM_IOCTL_DEF(DRM_IOCTL_DUMB_SET_LABEL, drm_dumb_set_label_ioctl, DRM_RENDER_ALLOW),
 };
 
 #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index cf13470810a5..501a3924354a 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -715,6 +715,22 @@ struct drm_driver {
 			    struct drm_device *dev,
 			    uint32_t handle);
 
+	/**
+	 * @label:
+	 *
+	 * This label's a buffer object.
+	 *
+	 * Called by the user via ioctl.
+	 *
+	 * Returns:
+	 *
+	 * Zero on success, negative errno on failure.
+	 */
+	int (*label)(struct drm_device *dev,
+				struct drm_file *file_priv,
+				uint32_t handle,
+				char *label);
+
 	/**
 	 * @gem_vm_ops: Driver private ops for this object
 	 *
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 6aaba14f5972..f801c054e972 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -237,6 +237,13 @@ struct drm_gem_object {
 	 */
 	int name;
 
+	/**
+	 * @label:
+	 *
+	 * Label for this object, should be a human readable string.
+	 */
+	char *label;
+
 	/**
 	 * @dma_buf:
 	 *
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 8a5b2f8f8eb9..309c3c091385 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -626,6 +626,25 @@ struct drm_gem_open {
 	__u64 size;
 };
 
+/** struct drm_dumb_set_label_object - ioctl argument for labelling BOs.
+ *
+ * This label's a BO with a userspace label
+ *
+ */
+struct drm_dumb_set_label_object {
+	/** Handle for the object being labelled. */
+	__u32 handle;
+
+	/** Label and label length.
+	 *  len includes the trailing NUL.
+	 */
+	__u32 len;
+	__u64 name;
+
+	/** Flags */
+	int flags;
+};
+
 #define DRM_CAP_DUMB_BUFFER		0x1
 #define DRM_CAP_VBLANK_HIGH_CRTC	0x2
 #define DRM_CAP_DUMB_PREFERRED_DEPTH	0x3
@@ -946,6 +965,7 @@ extern "C" {
 #define DRM_IOCTL_SYNCOBJ_QUERY		DRM_IOWR(0xCB, struct drm_syncobj_timeline_array)
 #define DRM_IOCTL_SYNCOBJ_TRANSFER	DRM_IOWR(0xCC, struct drm_syncobj_transfer)
 #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL	DRM_IOWR(0xCD, struct drm_syncobj_timeline_array)
+#define DRM_IOCTL_DUMB_SET_LABEL      DRM_IOWR(0xCE, struct drm_dumb_set_label_object)
 
 /**
  * Device specific ioctls should only be in their respective headers
-- 
2.17.1

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