kernel: implement a generic object signalling system

syscall/object.c

@@ -0,0 +1,75 @@
+#include <kernel/object.h>
+#include <kernel/sched.h>
+#include <kernel/syscall.h>
+#include <kernel/task.h>
+#include <kernel/wait.h>
+#include <mango/status.h>
+#include <mango/types.h>
+
+kern_status_t sys_kern_object_wait(kern_wait_item_t *items, size_t nr_items)
+{
+	if (nr_items > KERN_WAIT_MAX_ITEMS) {
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	struct task *self = current_task();
+	struct thread *self_thread = current_thread();
+	if (!validate_access_rw(self, items, nr_items * sizeof *items)) {
+		return KERN_MEMORY_FAULT;
+	}
+
+	kern_status_t status = KERN_OK;
+	struct object *objects[KERN_WAIT_MAX_ITEMS];
+	struct wait_item waiters[KERN_WAIT_MAX_ITEMS];
+	unsigned long irq_flags = 0;
+
+	size_t i = 0, to_release = 0;
+	bool signals_observed = false;
+	for (i = 0; i < nr_items; i++) {
+		kern_handle_t handle = items[i].w_handle;
+		handle_flags_t flags;
+		struct object *object = NULL;
+		status = task_resolve_handle(self, handle, &object, &flags);
+		if (status != KERN_OK) {
+			break;
+		}
+
+		objects[i] = object;
+
+		object_lock_irqsave(object, &irq_flags);
+		wait_item_init(&waiters[i], self_thread);
+		thread_wait_begin(&waiters[i], &object->ob_wq);
+
+		if (object->ob_signals & items[i].w_waitfor) {
+			signals_observed = true;
+			items[i].w_observed = object->ob_signals;
+		}
+
+		object_unlock_irqrestore(object, irq_flags);
+	}
+
+	if (signals_observed || status != KERN_OK) {
+		goto cleanup;
+	}
+
+	schedule(SCHED_NORMAL);
+
+	for (i = 0; i < nr_items; i++) {
+		object_lock_irqsave(objects[i], &irq_flags);
+
+		if (objects[i]->ob_signals & items[i].w_waitfor) {
+			signals_observed = true;
+		}
+
+		object_unlock_irqrestore(objects[i], irq_flags);
+	}
+
+cleanup:
+	to_release = i;
+	for (i = 0; i < to_release; i++) {
+		thread_wait_end(&waiters[i], &objects[i]->ob_wq);
+		object_unref(objects[i]);
+	}
+
+	return status;
+}