staging: vc04_services: vchiq_core: Stop kthreads on shutdown

The various kthreads thread functions (slot_handler_func, sync_func,
recycle_func) in vchiq_core and vchiq_keepalive_thread_func in
vchiq_arm should be stopped on vchiq_shutdown().

This also address the following TODO item:
 * Fix kernel module support

hence drop it from the TODO item list.
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Link: https://lore.kernel.org/r/20240321130737.898154-6-umang.jain@ideasonboard.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/TODO

@@ -16,13 +16,6 @@ some of the ones we want:
   to manage these buffers as dmabufs so that we can zero-copy import
   camera images into vc4 for rendering/display.
 
-* Fix kernel module support
-
-Even the VPU firmware doesn't support a VCHI re-connect, the driver
-should properly handle a module unload. This also includes that all
-resources must be freed (kthreads, debugfs entries, ...) and global
-variables avoided.
-
 * Documentation
 
 A short top-down description of this driver's architecture (function of

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -726,8 +726,9 @@ void free_bulk_waiter(struct vchiq_instance *instance)
 
 int vchiq_shutdown(struct vchiq_instance *instance)
 {
-	int status = 0;
 	struct vchiq_state *state = instance->state;
+	struct vchiq_arm_state *arm_state;
+	int status = 0;
 
 	if (mutex_lock_killable(&state->mutex))
 		return -EAGAIN;
@@ -739,6 +740,9 @@ int vchiq_shutdown(struct vchiq_instance *instance)
 
 	dev_dbg(state->dev, "core: (%p): returning %d\n", instance, status);
 
+	arm_state = vchiq_platform_get_arm_state(state);
+	kthread_stop(arm_state->ka_thread);
+
 	free_bulk_waiter(instance);
 	kfree(instance);
 
@@ -1310,7 +1314,7 @@ vchiq_keepalive_thread_func(void *v)
 		goto shutdown;
 	}
 
-	while (1) {
+	while (!kthread_should_stop()) {
 		long rc = 0, uc = 0;
 
 		if (wait_for_completion_interruptible(&arm_state->ka_evt)) {

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c

@@ -1936,7 +1936,7 @@ slot_handler_func(void *v)
 
 	DEBUG_INITIALISE(local);
 
-	while (1) {
+	while (!kthread_should_stop()) {
 		DEBUG_COUNT(SLOT_HANDLER_COUNT);
 		DEBUG_TRACE(SLOT_HANDLER_LINE);
 		remote_event_wait(&state->trigger_event, &local->trigger);
@@ -1978,7 +1978,7 @@ recycle_func(void *v)
 	if (!found)
 		return -ENOMEM;
 
-	while (1) {
+	while (!kthread_should_stop()) {
 		remote_event_wait(&state->recycle_event, &local->recycle);
 
 		process_free_queue(state, found, length);
@@ -1997,7 +1997,7 @@ sync_func(void *v)
 			state->remote->slot_sync);
 	int svc_fourcc;
 
-	while (1) {
+	while (!kthread_should_stop()) {
 		struct vchiq_service *service;
 		int msgid, size;
 		int type;
@@ -2844,6 +2844,10 @@ vchiq_shutdown_internal(struct vchiq_state *state, struct vchiq_instance *instan
 		(void)vchiq_remove_service(instance, service->handle);
 		vchiq_service_put(service);
 	}
+
+	kthread_stop(state->sync_thread);
+	kthread_stop(state->recycle_thread);
+	kthread_stop(state->slot_handler_thread);
 }
 
 int