[PATCH 1/3] drm/gem: Add callback for when handle count goes to 0

[Alex Deucher <alexander.deucher@amd.com>]

From: Mukul Joshi <mukul.joshi@amd.com>

Add an optional callback for driver-specific cleanup when the GEM
handle of an object is freed. This will be used by AMDGPU to enable
freeing of memory exported to other nodes in a UALink pod once all
user mode references are gone.

The callback is called outside the object_name_lock and before
releasing the reference count on the GEM object

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c |  9 +++++++++
 drivers/gpu/drm/drm_gem.c               |  5 ++++-
 include/drm/drm_gem.h                   | 11 +++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index f754a4a3a1c22..0d579517c03ce 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -386,6 +386,14 @@ static int amdgpu_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_str
 	return drm_gem_ttm_mmap(obj, vma);
 }
 
+static void amdgpu_gem_object_handle_free(struct drm_gem_object *gobj)
+{
+	struct amdgpu_bo *aobj = gem_to_amdgpu_bo(gobj);
+
+	amdgpu_ualink_revoke_exported_memory(aobj);
+
+}
+
 const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
 	.free = amdgpu_gem_object_free,
 	.open = amdgpu_gem_object_open,
@@ -395,6 +403,7 @@ const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
 	.vunmap = drm_gem_ttm_vunmap,
 	.mmap = amdgpu_gem_object_mmap,
 	.vm_ops = &amdgpu_gem_vm_ops,
+	.handle_free = amdgpu_gem_object_handle_free
 };
 
 static bool amdgpu_gem_are_domains_valid(u32 domains)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index e3ed684ddcf29..6a86bd2a0343e 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -354,8 +354,11 @@ void drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj)
 	}
 	mutex_unlock(&dev->object_name_lock);
 
-	if (final)
+	if (final) {
+		if (obj->funcs->handle_free)
+			obj->funcs->handle_free(obj);
 		drm_gem_object_put(obj);
+	}
 }
 
 /*
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 8a704f6a65c15..95d8ae6f85df7 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -227,6 +227,17 @@ struct drm_gem_object_funcs {
 	 */
 	size_t (*rss)(struct drm_gem_object *obj);
 
+	/**
+	 * @handle_free:
+	 *
+	 * This callback is called when the GEM handle count goes down to 0.
+	 * It is currently used by AMDGPU driver to release their exported BO
+	 * handles.
+	 *
+	 * This callback is optional.
+	 */
+	void (*handle_free)(struct drm_gem_object *obj);
+
 	/**
 	 * @vm_ops:
 	 *
-- 
2.55.0