accel/amdxdna: Remove amdxdna_flush()

amdxdna_flush() was introduced to ensure that the device does not access
a process address space after it has been freed. However, this is no
longer necessary because the driver now increments the mm reference count
when a command is submitted and decrements it only after the command has
completed. This guarantees that the process address space remains valid
for the entire duration of command execution. Remove amdxdna_flush to
simplify the teardown path.

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20251216031311.2033399-1-lizhi.hou@amd.com

Author: houlz0507

drivers/accel/amdxdna/amdxdna_pci_drv.c

@@ -105,43 +105,38 @@ static int amdxdna_drm_open(struct drm_device *ddev, struct drm_file *filp)
 	return ret;
 }
 
-static void amdxdna_drm_close(struct drm_device *ddev, struct drm_file *filp)
+static void amdxdna_client_cleanup(struct amdxdna_client *client)
 {
-	struct amdxdna_client *client = filp->driver_priv;
-	struct amdxdna_dev *xdna = to_xdna_dev(ddev);
-
-	XDNA_DBG(xdna, "closing pid %d", client->pid);
-
+	list_del(&client->node);
+	amdxdna_hwctx_remove_all(client);
 	xa_destroy(&client->hwctx_xa);
 	cleanup_srcu_struct(&client->hwctx_srcu);
 	mutex_destroy(&client->mm_lock);
+
 	if (client->dev_heap)
 		drm_gem_object_put(to_gobj(client->dev_heap));
 
 	iommu_sva_unbind_device(client->sva);
 
-	XDNA_DBG(xdna, "pid %d closed", client->pid);
 	kfree(client);
 }
 
-static int amdxdna_flush(struct file *f, fl_owner_t id)
+static void amdxdna_drm_close(struct drm_device *ddev, struct drm_file *filp)
 {
-	struct drm_file *filp = f->private_data;
 	struct amdxdna_client *client = filp->driver_priv;
-	struct amdxdna_dev *xdna = client->xdna;
+	struct amdxdna_dev *xdna = to_xdna_dev(ddev);
 	int idx;
 
-	XDNA_DBG(xdna, "PID %d flushing...", client->pid);
+	XDNA_DBG(xdna, "closing pid %d", client->pid);
+
 	if (!drm_dev_enter(&xdna->ddev, &idx))
-		return 0;
+		return;
 
 	mutex_lock(&xdna->dev_lock);
-	list_del_init(&client->node);
-	amdxdna_hwctx_remove_all(client);
+	amdxdna_client_cleanup(client);
 	mutex_unlock(&xdna->dev_lock);
 
 	drm_dev_exit(idx);
-	return 0;
 }
 
 static int amdxdna_drm_get_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
@@ -217,7 +212,6 @@ static const struct file_operations amdxdna_fops = {
 	.owner		= THIS_MODULE,
 	.open		= accel_open,
 	.release	= drm_release,
-	.flush		= amdxdna_flush,
 	.unlocked_ioctl	= drm_ioctl,
 	.compat_ioctl	= drm_compat_ioctl,
 	.poll		= drm_poll,
@@ -333,8 +327,7 @@ static void amdxdna_remove(struct pci_dev *pdev)
 	client = list_first_entry_or_null(&xdna->client_list,
 					  struct amdxdna_client, node);
 	while (client) {
-		list_del_init(&client->node);
-		amdxdna_hwctx_remove_all(client);
+		amdxdna_client_cleanup(client);
 
 		client = list_first_entry_or_null(&xdna->client_list,
 						  struct amdxdna_client, node);