drm/gpuvm: reference count drm_gpuvm structures

Implement reference counting for struct drm_gpuvm.

Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231108001259.15123-10-dakr@redhat.com

1 files changed, 30 insertions, 1 deletions

diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
index 0c2e24155a93..4e6e1fd3485a 100644
--- a/include/drm/drm_gpuvm.h
+++ b/include/drm/drm_gpuvm.h
@@ -248,6 +248,11 @@ struct drm_gpuvm {
 	} rb;
 
 	/**
+	 * @kref: reference count of this object
+	 */
+	struct kref kref;
+
+	/**
 	 * @kernel_alloc_node:
 	 *
 	 * &drm_gpuva representing the address space cutout reserved for
@@ -273,7 +278,23 @@ void drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name,
 		    u64 start_offset, u64 range,
 		    u64 reserve_offset, u64 reserve_range,
 		    const struct drm_gpuvm_ops *ops);
-void drm_gpuvm_destroy(struct drm_gpuvm *gpuvm);
+
+/**
+ * drm_gpuvm_get() - acquire a struct drm_gpuvm reference
+ * @gpuvm: the &drm_gpuvm to acquire the reference of
+ *
+ * This function acquires an additional reference to @gpuvm. It is illegal to
+ * call this without already holding a reference. No locks required.
+ */
+static inline struct drm_gpuvm *
+drm_gpuvm_get(struct drm_gpuvm *gpuvm)
+{
+	kref_get(&gpuvm->kref);
+
+	return gpuvm;
+}
+
+void drm_gpuvm_put(struct drm_gpuvm *gpuvm);
 
 bool drm_gpuvm_range_valid(struct drm_gpuvm *gpuvm, u64 addr, u64 range);
 bool drm_gpuvm_interval_empty(struct drm_gpuvm *gpuvm, u64 addr, u64 range);
@@ -674,6 +695,14 @@ static inline void drm_gpuva_init_from_op(struct drm_gpuva *va,
  */
 struct drm_gpuvm_ops {
 	/**
+	 * @vm_free: called when the last reference of a struct drm_gpuvm is
+	 * dropped
+	 *
+	 * This callback is mandatory.
+	 */
+	void (*vm_free)(struct drm_gpuvm *gpuvm);
+
+	/**
 	 * @op_alloc: called when the &drm_gpuvm allocates
 	 * a struct drm_gpuva_op
 	 *