kernel: implement a generic object signalling system

include/kernel/channel.h

@@ -9,7 +9,7 @@ struct msg;
 struct channel {
 	struct object c_base;
 	unsigned int c_id;
-	struct waitqueue c_wq;
+	unsigned int c_msg_waiting;
 	struct btree c_msg;
 	struct btree_node c_node;
 };

include/kernel/object.h

@@ -88,9 +88,11 @@ struct object {
 	koid_t ob_id;
 	struct object_type *ob_type;
 	spin_lock_t ob_lock;
+	uint32_t ob_signals;
 	unsigned int ob_refcount;
 	unsigned int ob_handles;
 	struct queue_entry ob_list;
+	struct waitqueue ob_wq;
 } __aligned(sizeof(long));
 
 extern kern_status_t object_bootstrap(void);
@@ -116,6 +118,13 @@ extern void object_unlock_pair_irqrestore(
 	struct object *b,
 	unsigned long flags);
 
+extern void object_assert_signal(struct object *obj, uint32_t signals);
+extern void object_clear_signal(struct object *obj, uint32_t signals);
+extern void object_wait_signal(
+	struct object *obj,
+	uint32_t signals,
+	unsigned long *irq_flags);
+
 #ifdef __cplusplus
 }
 #endif

kernel/channel.c

@@ -5,6 +5,7 @@
 #include <kernel/thread.h>
 #include <kernel/util.h>
 #include <kernel/vm-region.h>
+#include <mango/signal.h>
 
 #define CHANNEL_CAST(p) OBJECT_C_CAST(struct channel, c_base, &channel_type, p)
 
@@ -100,6 +101,7 @@ static struct msg *get_next_msg(
 		if (msg->msg_status == KMSG_WAIT_RECEIVE) {
 			msg->msg_status = KMSG_WAIT_REPLY;
 			msg->msg_sender_port->p_status = PORT_REPLY_BLOCKED;
+			channel->c_msg_waiting--;
 			return msg;
 		}
 
@@ -119,7 +121,8 @@ extern kern_status_t channel_enqueue_msg(
 		msg->msg_id++;
 	}
 
-	wakeup_one(&channel->c_wq);
+	channel->c_msg_waiting++;
+	object_assert_signal(&channel->c_base, CHANNEL_SIGNAL_MSG_RECEIVED);
 
 	return KERN_OK;
 }
@@ -129,11 +132,21 @@ extern kern_status_t channel_recv_msg(
 	kern_msg_t *out_msg,
 	unsigned long *irq_flags)
 {
-	struct wait_item waiter;
 	struct thread *self = current_thread();
 	struct msg *msg = NULL;
 	unsigned long msg_lock_flags;
 
+	msg = get_next_msg(channel, &msg_lock_flags);
+	if (!msg) {
+		return KERN_NO_ENTRY;
+	}
+
+	if (channel->c_msg_waiting == 0) {
+		object_clear_signal(
+			&channel->c_base,
+			CHANNEL_SIGNAL_MSG_RECEIVED);
+	}
+#if 0
 	wait_item_init(&waiter, self);
 	for (;;) {
 		thread_wait_begin(&waiter, &channel->c_wq);
@@ -147,6 +160,7 @@ extern kern_status_t channel_recv_msg(
 		object_lock_irqsave(&channel->c_base, irq_flags);
 	}
 	thread_wait_end(&waiter, &channel->c_wq);
+#endif
 
 	/* msg is now set to the next message to process */
 

kernel/object.c

@@ -226,3 +226,35 @@ struct object *object_header(void *p)
 
 	return obj;
 }
+
+void object_assert_signal(struct object *obj, uint32_t signals)
+{
+	obj->ob_signals |= signals;
+	wakeup_queue(&obj->ob_wq);
+}
+
+void object_clear_signal(struct object *obj, uint32_t signals)
+{
+	obj->ob_signals &= ~signals;
+}
+
+void object_wait_signal(
+	struct object *obj,
+	uint32_t signals,
+	unsigned long *irq_flags)
+{
+	struct thread *self = current_thread();
+	struct wait_item waiter;
+	wait_item_init(&waiter, self);
+	for (;;) {
+		thread_wait_begin(&waiter, &obj->ob_wq);
+		if (obj->ob_signals & signals) {
+			break;
+		}
+
+		object_unlock_irqrestore(obj, *irq_flags);
+		schedule(SCHED_NORMAL);
+		object_lock_irqsave(obj, irq_flags);
+	}
+	thread_wait_end(&waiter, &obj->ob_wq);
+}

libmango/include-user/mango/object.h

@@ -0,0 +1,8 @@
+#ifndef MANGO_OBJECT_H_
+#define MANGO_OBJECT_H_
+
+#include <mango/types.h>
+
+extern kern_status_t kern_object_wait(kern_wait_item_t *items, size_t nr_items);
+
+#endif

libmango/include/mango/signal.h

@@ -0,0 +1,10 @@
+#ifndef MANGO_SIGNAL_H_
+#define MANGO_SIGNAL_H_
+
+#define CHANNEL_SIGNAL_MSG_RECEIVED           0x01u
+
+#define VM_CONTROLLER_SIGNAL_REQUEST_RECEIVED 0x01u
+
+#define EQUEUE_SIGNAL_PACKET_RECEIVED         0x01u
+
+#endif

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;
+}