Allow users to request a asynchronous notification

This patch adds functionality to request an asynchronous notification
if some other process has send a message to it. We currently send a
SIGALRM to avoid any changes to core infrastructure of signal handling.
Ideally we should implement a separate signal for this. Currently there
is an obvious disadvantage of not being able to use SIGALRM with alarm,
if we are using this functionality.

minix/commands/service/parse.c

@@ -855,6 +855,7 @@ struct
 	{ "MQ_REC",		SYS_MQ_REC},
 	{ "MQ_SET_ATTR",	SYS_MQ_SET_ATTR},
 	{ "MQ_GET_ATTR",	SYS_MQ_GET_ATTR},
+	{ "MQ_REQ_NOTIFY",	SYS_MQ_REQ_NOTIFY},
 	{ NULL,		0 }
 };
 

minix/include/minix/com.h

@@ -268,9 +268,10 @@
 #  define SYS_MQ_REC	(KERNEL_CALL + 61)	/* sys_mq_rec */
 #  define SYS_MQ_SET_ATTR	(KERNEL_CALL + 62)	/* sys_mq_set_attributes */
 #  define SYS_MQ_GET_ATTR	(KERNEL_CALL + 63)	/* sys_mq_get_attributes */
+#  define SYS_MQ_REQ_NOTIFY	(KERNEL_CALL + 64)	/* sys_mq_request_notify */
 
 /* Total */
-#define NR_SYS_CALLS	64	/* number of kernel calls */
+#define NR_SYS_CALLS	65	/* number of kernel calls */
 
 #define SYS_CALL_MASK_SIZE BITMAP_CHUNKS(NR_SYS_CALLS)
 

minix/include/minix/ipc.h

@@ -1273,6 +1273,13 @@ typedef struct {
 } mess_lsys_krn_sys_mqueue_attribute;
 _ASSERT_MSG_SIZE(mess_lsys_krn_sys_mqueue_attribute);
 
+typedef struct {
+	int notify_on_off;
+
+	uint8_t padding[52];
+} mess_lsys_krn_sys_mqueue_notify;
+_ASSERT_MSG_SIZE(mess_lsys_krn_sys_mqueue_notify);
+
 typedef struct {
 	void		*vec_addr;
 	int		vec_size;
@@ -2295,6 +2302,7 @@ typedef struct noxfer_message {
 		mess_lsys_krn_sys_mqueue_send m_lsys_krn_sys_mqueue_send;
 		mess_lsys_krn_sys_mqueue_receive m_lsys_krn_sys_mqueue_receive;
 		mess_lsys_krn_sys_mqueue_attribute m_lsys_krn_sys_mqueue_attribute;
+		mess_lsys_krn_sys_mqueue_notify m_lsys_krn_sys_mqueue_notify;
 
 		u8_t size[56];	/* message payload may have 56 bytes at most */
 	};

minix/include/minix/syslib.h

@@ -281,6 +281,7 @@ int sys_mq_receive(int mqdes, char *msg_ptr, unsigned int msg_prio);
 int sys_mq_get_attr(int *no_of_messages, int *no_of_queues, int *blocking);
 int sys_mq_set_attr(int no_of_messages, int no_of_queues, int blocking);
 int sys_mq_close(int mqdes);
+int sys_mq_request_notify(int notify_on_off);
 int sys_endpoint_from_pid(pid_t pid, endpoint_t *endpoint);
 
 #endif /* _SYSLIB_H */

minix/kernel/mqueue.c

@@ -21,6 +21,7 @@ int initialize_message_queues(void)
 	number_of_queues = MAX_QUEUES;
 	number_of_messages = MAX_MESSAGES;
 	mq_blocking = MQ_NON_BLOCKING;
+	notify = NOTIFY_OFF;
 
 	for (int i = 0; i < number_of_queues; i++) {
 		mq.queue_slot_empty[i] = EMPTY;
@@ -154,6 +155,21 @@ int mq_send(mqd_t mqdes, const char *msg_ptr, unsigned int msg_prio, endpoint_t
 	mq.msg[mqdes].msge[empty_slot_pos].timestamp = get_monotonic();
 	mq.msg[mqdes].num_msgs++;
 
+	if (notify) {
+		proc_nr_t proc_nr;
+
+		for (int i = 0; i < MAX_RECEIVERS; i++) {
+			if (dst[i] != -1) {
+				/* Translate endpoint to process number */
+				if (!isokendpt(dst[i], &proc_nr))
+					goto exit;
+				else
+					cause_sig(proc_nr, SIGALRM);
+			}
+		}
+	}
+
+ exit:
 	return 0;
 }
 
@@ -229,3 +245,13 @@ int clean_message_queue(mqd_t mqdes)
 
 	return 0;
 }
+
+int mq_notify(int notify_on_off)
+{
+	if (notify_on_off)
+		notify = NOTIFY_ON;
+	else
+		notify = NOTIFY_OFF;
+
+	return 0;
+}

minix/kernel/mqueue.h

@@ -29,6 +29,9 @@
 #define MQ_BLOCKING	0
 #define MQ_NON_BLOCKING	1
 
+#define NOTIFY_ON	1
+#define NOTIFY_OFF	0
+
 typedef int mqd_t;
 
 typedef struct message_entity {
@@ -56,6 +59,7 @@ typedef struct message_queue {
 int number_of_messages;
 int number_of_queues;
 int mq_blocking;
+int notify;
 
 int initialize_message_queues(void);
 int deinitialize_message_queues(void);
@@ -66,6 +70,7 @@ size_t mq_receive(mqd_t mqdes, char *msg_ptr, unsigned int msg_prio, endpoint_t
 int mq_get_attributes(int *no_of_msgs, int *no_of_queues, int *blocking);
 int mq_set_attributes(int no_of_msgs, int no_of_queues, int blocking);
 int mq_close(mqd_t mqdes);
+int mq_notify(int notify_on_off);
 
 int clean_message_queue(mqd_t mqdes);
 int message_index_with_highprio(mqd_t mqdes, endpoint_t dst);

minix/kernel/system.c

@@ -275,6 +275,7 @@ void system_init(void)
   map(SYS_MQ_REC, do_mq_rec);		/* receive from a message queue */
   map(SYS_MQ_SET_ATTR, do_mq_set_attr);	/* set message queue attributes */
   map(SYS_MQ_GET_ATTR, do_mq_get_attr);	/* get message queue attributes */
+  map(SYS_MQ_REQ_NOTIFY, do_mq_request_notify); /* request notification for receive */
 
 }
 /*===========================================================================*

minix/kernel/system.h

@@ -236,5 +236,10 @@ int do_mq_get_attr(struct proc * caller, message *m_ptr);
 #define do_mq_get_attr NULL
 #endif
 
+int do_mq_request_notify(struct proc * caller, message *m_ptr);
+#if ! USE_MQ_IPC
+#define do_mq_request_notify NULL
+#endif
+
 #endif	/* SYSTEM_H */
 

minix/kernel/system/Makefile.inc

@@ -43,7 +43,8 @@ SRCS+= 	\
 	do_mq_send.c \
 	do_mq_rec.c \
 	do_mq_set_attribute.c \
-	do_mq_get_attribute.c
+	do_mq_get_attribute.c \
+	do_mq_request_notify.c
 
 .if ${MACHINE_ARCH} == "i386"
 SRCS+=  \

minix/kernel/system/do_mq_request_notify.c

@@ -0,0 +1,26 @@
+/* The kernel call implemented in this file:
+ *   m_type:	SYS_MQ_REQUEST_NOTIFY
+ *
+ */
+
+#include "kernel/mqueue.h"
+#include "kernel/system.h"
+#include "kernel/vm.h"
+#include <signal.h>
+#include <string.h>
+#include <assert.h>
+
+#include <minix/endpoint.h>
+#include <minix/u64.h>
+
+#if USE_MQ_IPC
+
+/*===========================================================================*
+ *				do_mq_request_notify			     *
+ *===========================================================================*/
+int do_mq_request_notify(struct proc * caller, message * m_ptr)
+{
+	return mq_notify(m_ptr->m_lsys_krn_sys_mqueue_notify.notify_on_off);
+}
+
+#endif /* USE_MQ_IPC */

minix/lib/libsys/Makefile

@@ -94,6 +94,7 @@ SRCS+=  \
 	sys_mq_receive.c \
 	sys_mq_set_attr.c \
 	sys_mq_get_attr.c \
+	sys_mq_request_notify.c \
 	sys_endpoint_from_pid.c \
 	taskcall.c \
 	tickdelay.c \

minix/lib/libsys/sys_mq_request_notify.c

@@ -0,0 +1,15 @@
+#include "syslib.h"
+#include <string.h>
+#include <machine/archtypes.h>
+#include <minix/timers.h>
+#include <minix/sysutil.h>
+#include <minix/vm.h>
+
+int sys_mq_request_notify(int notify_on_off)
+{
+	message m;
+
+	m.m_lsys_krn_sys_mqueue_notify.notify_on_off = notify_on_off;
+
+	return (_kernel_call(SYS_MQ_REQ_NOTIFY, &m));
+}