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* [RFC][PATCH] Posix Message Queues
@ 2003-07-14 17:43 Michal Wronski
  0 siblings, 0 replies; 3+ messages in thread
From: Michal Wronski @ 2003-07-14 17:43 UTC (permalink / raw)
  To: linux-kernel


This patch (against 2.5.73) implements POSIX message queues
It's implemented as a filesystem called 'mqueue'. Necessary operations are
done via ioctls.
Patch was well tested (passed all tests from Open Posix Test Suite).

To use it you will also need mqueue library, available from
http://www.mat.uni.torun.pl/~wrona/posix_ipc
(there is also patch against 2.4.21)

Any comment will be welcome

Michal

diff -urN linux-2.5.73-org/CREDITS linux-2.5.73/CREDITS
--- linux-2.5.73-org/CREDITS	2003-07-04 13:55:26.000000000 +0200
+++ linux-2.5.73/CREDITS	2003-07-04 14:03:16.000000000 +0200
@@ -279,6 +279,15 @@
 S: Greenbelt, Maryland 20771
 S: USA

+N: Krzysztof Benedyczak
+E: golbi@mat.uni.torun.pl
+W: http://www.mat.uni.torun.pl/~golbi
+D: POSIX message queues fs (with M. Wronski)
+S: ul. Podmiejska 52
+S: Radunica
+S: 83-000 Pruszcz Gdanski
+S: Poland
+
 N: Randolph Bentson
 E: bentson@grieg.seaslug.org
 W: http://www.aa.net/~bentson/
@@ -3445,6 +3454,14 @@
 S: Portland, OR 97204
 S: USA

+N: Michal Wronski
+E: wrona@mat.uni.torun.pl
+W: http://www.mat.uni.torun.pl/~wrona
+D: POSIX message queues fs (with K. Benedyczak)
+S: ul. Teczowa 23/12
+S: 80-680 Gdansk-Sobieszewo
+S: Poland
+
 N: Frank Xia
 E: qx@math.columbia.edu
 D: Xiafs filesystem [defunct]
diff -urN linux-2.5.73-org/Documentation/ioctl-number.txt linux-2.5.73/Documentation/ioctl-number.txt
--- linux-2.5.73-org/Documentation/ioctl-number.txt	2003-07-04 13:55:20.000000000 +0200
+++ linux-2.5.73/Documentation/ioctl-number.txt	2003-07-07 22:10:56.000000000 +0200
@@ -187,5 +187,6 @@
 0xB0	all	RATIO devices		in development:
 					<mailto:vgo@ratio.de>
 0xB1	00-1F	PPPoX			<mailto:mostrows@styx.uwaterloo.ca>
+0xB2    00-0F   POSIX Message Queues    <http://www.mat.uni.torun.pl/~wrona/posix_ipc>
 0xCB	00-1F	CBM serial IEC bus	in development:
 					<mailto:michael.klein@puffin.lb.shuttle.de>
diff -urN linux-2.5.73-org/fs/Kconfig linux-2.5.73/fs/Kconfig
--- linux-2.5.73-org/fs/Kconfig	2003-07-04 13:55:17.000000000 +0200
+++ linux-2.5.73/fs/Kconfig	2003-07-04 14:06:33.000000000 +0200
@@ -881,6 +881,28 @@
 	  say M here and read <file:Documentation/modules.txt>.  The module
 	  will be called ramfs.

+config POSIX_MQUEUE_FS
+	tristate "POSIX Message Queues"
+	---help---
+	  POSIX variant of message queues is a part of IPC. In POSIX message
+	  queues every message has a priority which decides about succession
+	  of receiving it by a process. If you want to compile and run
+	  programs written e.g. for Solaris with use of its POSIX message
+	  queues (functions mq_*) say Y here. To use this feature you will
+	  also need mqueue library, available from
+	  <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
+
+	  POSIX message queues are visible as a filesystem called 'mqueue'
+	  and should be mounted in /dev/mqueue in order to work with standard
+	  library.
+
+	  If you want to compile this as a module ( = code which can be
+	  inserted in and removed from the running kernel whenever you want),
+	  say M here and read <file:Documentation/modules.txt>.  The module
+	  will be called mqueue.o.
+
+	  If unsure, say N.
+
 endmenu

 menu "Miscellaneous filesystems"
diff -urN linux-2.5.73-org/include/linux/mqueue.h linux-2.5.73/include/linux/mqueue.h
--- linux-2.5.73-org/include/linux/mqueue.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.5.73/include/linux/mqueue.h	2003-07-07 22:13:26.000000000 +0200
@@ -0,0 +1,42 @@
+#ifndef _LINUX_MQUEUE_H
+#define _LINUX_MQUEUE_H
+
+#include <asm/types.h>
+
+#define MQ_MAX		64	/* max number of message queues */
+#define MQ_MAXMSG 	40	/* max number of messages in each queue */
+#define MQ_MSGSIZE 	16384	/* max message size */
+#define MQ_MAXSYSSIZE	1048576	/* max size that all m.q. can have together */
+#define MQ_PRIO_MAX 	32768	/* max priority */
+
+typedef int mqd_t;
+
+struct kern_mq_attr {
+	__u32	mq_flags;	/* message queue flags */
+	__u32	mq_maxmsg;	/* maximum number of messages */
+	__u32	mq_msgsize;	/* maximum message size */
+	__u32	mq_curmsgs;	/* number of messages currently queued */
+};
+
+/*
+ *	struct for passing data via ioctl calls
+ */
+
+/* the same for send & receive */
+struct ioctl_mq_sndrcv {
+	__u64	msg_ptr;
+	__u32	msg_len;
+	__u64	msg_prio;	/* it is long or long* */
+	__u64	timeout;
+};
+
+#define MQ_IOC_CREATE	_IOW(0xB2, 0, struct kern_mq_attr)
+#define MQ_IOC_GETATTR	_IOR(0xB2, 1, struct kern_mq_attr)
+#define MQ_IOC_SEND	_IOW(0xB2, 2, struct ioctl_mq_sndrcv)
+#define MQ_IOC_RECEIVE	_IOR(0xB2, 3, struct ioctl_mq_sndrcv)
+#define MQ_IOC_NOTIFY	_IOW(0xB2, 4, struct sigevent)
+#define MQ_IOC_CLOSE	_IOW(0xB2, 5, void)
+#define MQ_IOC_SETATTR	_IOW(0xB2, 6, void)
+
+
+#endif
diff -urN linux-2.5.73-org/ipc/Makefile linux-2.5.73/ipc/Makefile
--- linux-2.5.73-org/ipc/Makefile	2003-07-04 13:55:25.000000000 +0200
+++ linux-2.5.73/ipc/Makefile	2003-07-04 14:00:06.000000000 +0200
@@ -5,3 +5,4 @@
 obj-y   := util.o

 obj-$(CONFIG_SYSVIPC) += msg.o sem.o shm.o
+obj-$(CONFIG_POSIX_MQUEUE_FS) += mqueue.o
diff -urN linux-2.5.73-org/ipc/mqueue.c linux-2.5.73/ipc/mqueue.c
--- linux-2.5.73-org/ipc/mqueue.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.5.73/ipc/mqueue.c	2003-07-10 13:53:56.000000000 +0200
@@ -0,0 +1,1077 @@
+/*
+ * POSIX message queues filesystem for Linux.
+ *
+ * Copyright (C) 2003 	Krzysztof Benedyczak 	(golbi@mat.uni.torun.pl)
+ *			Michal Wronski		(wrona@mat.uni.torun.pl)
+ *
+ * Spinlocks:		Mohamed Abbas 		(abbas.mohamed@intel.com)
+ *
+ * This file is released under the GPL.
+ */
+
+
+#include <linux/mqueue.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+
+#include <asm/atomic.h>
+#include <asm/current.h>
+#include <asm/uaccess.h>
+
+
+#define MQUEUE_MAGIC	0x19800202
+#define DIRENT_SIZE	20
+#define FILENT_SIZE	60
+#define SEND		0
+#define RECV		1
+
+struct msg {			/* this represent particular message */
+	unsigned int msg_len;	/* in the queue */
+	unsigned int msg_prio;
+	char *mtext;
+};
+
+struct ext_wait_queue {		/* queue of sleeping processes */
+	struct task_struct *task;
+	struct list_head list;
+};
+
+
+/* this stores extra data for inode - queue specific data */
+struct mqueue_inode_info {
+	struct kern_mq_attr attr;
+
+	/* this is messages heap */
+	struct msg *messages[MQ_MAXMSG+1]; /* +1 for first entry - sentinel */
+
+	struct task_struct *notify_task;
+	struct sigevent notify;
+
+	/* for processes waiting for free space or message (respectively) */
+	/* this is left mainly because of poll */
+	wait_queue_head_t wait_q[2];
+	/* avoids extra invocations of wake_up */
+	wait_queue_head_t wait_q2[2];
+	struct ext_wait_queue e_wait_q[2];	/* 0=free space   1=message */
+
+	__u32 qsize; /* size of queue in memory (msgs & struct) */
+	spinlock_t lock;
+	struct inode vfs_inode;
+};
+
+static struct inode_operations mqueue_dir_inode_operations;
+static struct file_operations mqueue_file_operations;
+static struct super_operations mqueue_super_ops;
+
+static unsigned long msgs_size;	  /* sum of sizes of all msgs in all queues */
+static unsigned int queues_count; /* number of existing queues */
+static spinlock_t mq_lock;
+static kmem_cache_t *mqueue_inode_cachep;
+
+
+static inline struct mqueue_inode_info *MQUEUE_I(struct inode *ino)
+{
+	return list_entry(ino, struct mqueue_inode_info, vfs_inode);
+}
+
+static struct inode *mqueue_get_inode(struct super_block *sb, int mode)
+{
+	struct inode *inode;
+	struct mqueue_inode_info *ino_extra;
+	struct msg *m;
+
+	m = kmalloc(sizeof(struct msg), GFP_KERNEL);
+	if (!m) return NULL;
+
+	inode = new_inode(sb);
+	if (inode) {
+		inode->i_mode = mode;
+		inode->i_uid = current->fsuid;
+		inode->i_gid = current->fsgid;
+		inode->i_blksize = PAGE_CACHE_SIZE;
+		inode->i_blocks = 0;
+		inode->i_rdev = NODEV;
+		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+		if ((mode & S_IFMT) == S_IFREG) {
+			inode->i_fop = &mqueue_file_operations;
+			inode->i_size = FILENT_SIZE;
+			/* mqueue specific info */
+			ino_extra = MQUEUE_I(inode);
+			spin_lock_init(&(ino_extra->lock));
+			init_waitqueue_head((&(ino_extra->wait_q[0])));
+			init_waitqueue_head((&(ino_extra->wait_q[1])));
+			init_waitqueue_head((&(ino_extra->wait_q2[0])));
+			init_waitqueue_head((&(ino_extra->wait_q2[1])));
+			INIT_LIST_HEAD(&(ino_extra->e_wait_q[0].list));
+			INIT_LIST_HEAD(&(ino_extra->e_wait_q[1].list));
+			ino_extra->notify_task = NULL;
+			ino_extra->notify.sigev_signo = 0;
+			ino_extra->notify.sigev_notify = SIGEV_NONE;
+			ino_extra->qsize = sizeof(struct mqueue_inode_info);
+			ino_extra->attr.mq_curmsgs = 0;
+			ino_extra->messages[0] = m;
+			ino_extra->messages[0]->msg_prio = MQ_PRIO_MAX + 1;
+			/* fill up with defaults
+			 * (mq_open will set it up via next ioctl call) */
+			ino_extra->attr.mq_maxmsg = 0;
+			ino_extra->attr.mq_msgsize = 0;
+		} else if ((mode & S_IFMT) == S_IFDIR) {
+			inode->i_nlink++;
+			/* Some things misbehave if size == 0 on a directory */
+			inode->i_size = 2 * DIRENT_SIZE;
+			inode->i_op = &mqueue_dir_inode_operations;
+			inode->i_fop = &simple_dir_operations;
+		}
+	} else
+		kfree(m);
+
+	return inode;
+}
+
+
+static int mqueue_parse_options(char *options, int *mode, uid_t * uid,
+				gid_t * gid, int silent)
+{
+	char *this_char, *value, *rest;
+
+	while ((this_char = strsep(&options, ",")) != NULL) {
+		if (!*this_char)
+			continue;
+		if ((value = strchr(this_char, '=')) != NULL) {
+			*value++ = 0;
+		} else {
+			if (!silent)
+				printk(KERN_ERR
+				       "mqueuefs: No value for mount option '%s'\n",
+				       this_char);
+			return 1;
+		}
+
+		if (!strcmp(this_char, "mode")) {
+			if (!mode)
+				continue;
+			*mode = simple_strtoul(value, &rest, 8);
+			if (*rest)
+				goto bad_val;
+		} else if (!strcmp(this_char, "uid")) {
+			if (!uid)
+				continue;
+			*uid = simple_strtoul(value, &rest, 0);
+			if (*rest)
+				goto bad_val;
+		} else if (!strcmp(this_char, "gid")) {
+			if (!gid)
+				continue;
+			*gid = simple_strtoul(value, &rest, 0);
+			if (*rest)
+				goto bad_val;
+		} else {
+			if (!silent)
+				printk(KERN_ERR
+				       "mqueuefs: Bad mount option %s\n",
+				       this_char);
+			return 1;
+		}
+	}
+	return 0;
+
+bad_val:
+	if (!silent)
+		printk(KERN_ERR
+		       "mqueuefs: Bad value '%s' for mount option '%s'\n",
+		       value, this_char);
+	return 1;
+
+}
+
+
+
+/* function for get_sb_nodev. Fill up our data in super block */
+static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+	uid_t uid = current->fsuid;
+	gid_t gid = current->fsgid;
+	int mode = S_IRWXUGO;
+
+	if (mqueue_parse_options(data, &mode, &uid, &gid, silent))
+		return -EINVAL;
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = MQUEUE_MAGIC;
+	sb->s_op = &mqueue_super_ops;
+
+	inode = mqueue_get_inode(sb, S_IFDIR | mode);
+
+	if (!inode)
+		return -ENOMEM;
+	inode->i_uid = uid;
+	inode->i_gid = gid;
+
+	sb->s_root = d_alloc_root(inode);
+
+	if (!sb->s_root) {
+		iput(inode);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
+					 int flags, const char *dev_name, void *data)
+{
+	return get_sb_nodev(fs_type, flags, data, mqueue_fill_super);
+}
+
+static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
+{
+	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
+
+	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR)
+		inode_init_once(&p->vfs_inode);
+}
+
+static int init_inode_cache(void)
+{
+	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
+		sizeof(struct mqueue_inode_info), 0, SLAB_HWCACHE_ALIGN, init_once, NULL);
+
+	if (mqueue_inode_cachep == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+static void destroy_inode_cache(void)
+{
+	if (kmem_cache_destroy(mqueue_inode_cachep))
+		printk(KERN_INFO "mqueue_inode_cache: not all structures were freed\n");
+}
+
+static struct inode *mqueue_alloc_inode(struct super_block *sb)
+{
+	struct mqueue_inode_info *ei;
+
+	ei = (struct mqueue_inode_info *)kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
+	if (!ei)
+		return NULL;
+	return &ei->vfs_inode;
+}
+
+static void mqueue_destroy_inode(struct inode *inode)
+{
+	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
+}
+
+static void mqueue_delete_inode(struct inode *ino)
+{
+	struct mqueue_inode_info *info;
+	int size;
+
+	if ((ino->i_mode & S_IFMT) == S_IFDIR) {
+		clear_inode(ino);
+		return;
+	}
+	info = MQUEUE_I(ino);
+	size = 0;
+	spin_lock(&info->lock);
+
+	while (info->attr.mq_curmsgs > 0) {
+		kfree(info->messages[info->attr.mq_curmsgs]->mtext);
+		size += info->messages[info->attr.mq_curmsgs]->msg_len;
+		kfree(info->messages[info->attr.mq_curmsgs]);
+		info->attr.mq_curmsgs--;
+	};
+	kfree(info->messages[0]);
+
+	spin_unlock(&info->lock);
+	clear_inode(ino);
+
+	spin_lock(&mq_lock);
+	msgs_size -= size;
+	queues_count--;
+	spin_unlock(&mq_lock);
+}
+
+static int mqueue_unlink(struct inode *dir, struct dentry *dent)
+{
+	struct inode *inode = dent->d_inode;
+
+	dir->i_size -= DIRENT_SIZE;
+	inode->i_nlink--;
+	dput(dent);
+	return 0;
+}
+
+static struct dentry *mqueue_lookup(struct inode * dir, struct dentry *dentry)
+{
+	if (dentry->d_name.len > NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	d_add(dentry, NULL);
+	return NULL;
+}
+
+static int mqueue_create(struct inode *dir, struct dentry *dent, int mode)
+{
+	struct inode *ino;
+	int error = 0;
+
+	spin_lock(&mq_lock);
+	if (queues_count >= MQ_MAX) {
+		error = -ENOSPC;
+		goto out;
+	}
+	queues_count++;
+	spin_unlock(&mq_lock);
+
+	ino = mqueue_get_inode(dir->i_sb, mode);
+	if (!ino) {
+		error = -ENOMEM;
+		spin_lock(&mq_lock);
+		queues_count--;
+		goto out;
+	}
+
+	dir->i_size += DIRENT_SIZE;
+	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+
+	d_instantiate(dent, ino);
+	dget(dent);
+	return 0;
+out:
+	spin_unlock(&mq_lock);
+	return error;
+}
+
+/*
+*	This is routine for system read from queue file.
+*	To avoid mess with doing some
+*	sort of mq_receive here we allow to read only: queue size &
+* 	notification info (the only values that are interesting from user
+*	point of view and aren't accessible through std. routines)
+*/
+static ssize_t mqueue_read_file(struct file *file, char *data, size_t size,
+				loff_t * off)
+{
+	char buffer[FILENT_SIZE + 1];
+	struct mqueue_inode_info *info = MQUEUE_I(file->f_dentry->d_inode);
+	ssize_t retval = 0;
+
+	if (*off >= FILENT_SIZE)
+		return 0;
+
+	snprintf(buffer, FILENT_SIZE + 1,
+		 "QSIZE:%-10u NOTIFY:%-5d SIGNO:%-6d NOTIFY_PID:%-6d",
+		 info->qsize, info->notify.sigev_notify,
+		 info->notify.sigev_signo, (info->notify_task) ? (info->notify_task)->pid : 0);
+
+	retval = FILENT_SIZE - *off;
+	if (copy_to_user(data, buffer + *off, retval)) {
+		retval = (ssize_t) -EFAULT;
+		goto out;
+	}
+	*off += retval;
+out:
+	return retval;
+}
+
+
+static int mqueue_release_file(struct inode *ino, struct file *f)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(ino);
+
+	spin_lock(&info->lock);
+	if (info->notify_task == current) {
+		info->notify_task = NULL;
+		info->notify.sigev_signo = 0;
+		info->notify.sigev_notify = SIGEV_NONE;
+	}
+	spin_unlock(&info->lock);
+	return 0;
+}
+
+
+static unsigned int mqueue_poll_file(struct file *file, struct poll_table_struct *poll_tab)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(file->f_dentry->d_inode);
+	int retval = 0;
+
+	poll_wait(file, &info->wait_q[0], poll_tab);
+	poll_wait(file, &info->wait_q[1], poll_tab);
+
+	spin_lock(&info->lock);
+	if (info->attr.mq_curmsgs)
+		retval = POLLIN | POLLRDNORM;
+
+	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
+		retval |= POLLOUT | POLLWRNORM;
+	spin_unlock(&info->lock);
+
+	return retval;
+}
+
+/*
+*  This cut&paste version of wait_event() without event checking & with
+*  exclusive adding to queue.
+*/
+void inline wait_exclusive(wait_queue_head_t * wq,
+			   struct mqueue_inode_info *i)
+{
+	wait_queue_t wait;
+	init_waitqueue_entry(&wait, current);
+
+	add_wait_queue_exclusive(wq, &wait);
+	set_current_state(TASK_UNINTERRUPTIBLE);
+
+	spin_unlock(&i->lock);
+	schedule();
+	spin_lock(&i->lock);
+
+	current->state = TASK_RUNNING;
+	remove_wait_queue(wq, &wait);
+}
+
+/* Removes from info->e_wait_q[sr] current process */
+static void wq_remove(struct mqueue_inode_info *info, int sr)
+{
+	struct ext_wait_queue *ptr;
+
+	if (!list_empty(&(info->e_wait_q[sr].list)))
+		list_for_each_entry(ptr, &(info->e_wait_q[sr].list), list) {
+			if (ptr->task->pid == current->pid) {
+				list_del(&(ptr->list));
+				kfree(ptr);
+				break;
+			}
+		}
+}
+
+/* adds current to info->e_wait_q[sr] before element with smaller prio */
+static inline void wq_add(struct mqueue_inode_info *info, int sr,
+			struct ext_wait_queue *tmp)
+{
+	struct ext_wait_queue *ptr;
+
+	tmp->task = current;
+
+	if (list_empty(&info->e_wait_q[sr].list))
+		list_add(&tmp->list, &info->e_wait_q[sr].list);
+	else {
+		list_for_each_entry(ptr, &info->e_wait_q[sr].list, list)
+			if (ptr->task->static_prio <= current->static_prio) {
+				/* we add before ptr element */
+				__list_add(&tmp->list, ptr->list.prev, &ptr->list);
+				return;
+			}
+		/* we add on tail */
+		list_add_tail(&tmp->list, &info->e_wait_q[sr].list);
+	}
+	return;
+}
+
+/* removes from info->e_wait_q[sr] current process.
+ * Only for wq_sleep(): as we are here current must be one
+ * before-first (last) (meaning first in order as our 'queue' is inversed) */
+static inline void wq_remove_last(struct mqueue_inode_info *info, int sr)
+{
+	struct ext_wait_queue *tmp =
+	    list_entry(info->e_wait_q[sr].list.prev, struct ext_wait_queue, list);
+	list_del(&(tmp->list));
+	kfree(tmp);
+}
+
+/* adds current process
+ * sr: SEND or RECV
+ * Returns: 0, -EINTR, -ETIMEDOUT */
+static int wq_sleep(struct mqueue_inode_info *info, int sr,
+		    signed long timeout, struct ext_wait_queue *wq_ptr)
+{
+	wait_queue_t __wait;
+	long error;
+
+	wq_add(info, sr, wq_ptr);
+
+	init_waitqueue_entry(&__wait, current);
+
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if ((current->pid == (list_entry(info->e_wait_q[sr].list.prev, struct ext_wait_queue, list))->task->pid)
+			&& ((info->attr.mq_curmsgs > 0 && sr == RECV)
+			|| (info->attr.mq_curmsgs < info->attr.mq_maxmsg && sr == SEND)))
+			break;
+
+		if (signal_pending(current)) {
+			current->state = TASK_RUNNING;
+			wq_remove(info, sr);
+			return -EINTR;
+		}
+
+		spin_unlock(&info->lock);
+		error = schedule_timeout(timeout);
+		spin_lock(&info->lock);
+
+		if ((!error) && (!signal_pending(current))) {
+			wq_remove(info, sr);
+			return -ETIMEDOUT;
+		}
+	}
+	current->state = TASK_RUNNING;
+	wq_remove_last(info, sr);
+
+	return 0;
+}
+
+/* wakes up all sleeping processes in queue */
+static void wq_wakeup(struct mqueue_inode_info *info, int sr)
+{
+	if (sr == SEND) {
+		/* We can't invoke wake_up for processes waiting for free space
+		 * if there is less then MAXMSG-1 messages - then wake_up was
+		 * invoked previously (and finished) but mq_sleep() of proper
+		 * (only one) process didn't start to continue running yet,
+		 * thus we must wait until this process receives IT'S message
+		 */
+		if ((info->attr.mq_curmsgs < info->attr.mq_maxmsg - 1)
+		    && (!list_empty(&info->e_wait_q[sr].list)))
+			wait_exclusive(&(info->wait_q2[sr]), info);
+	} else {
+		/* As above but for processes waiting for new message */
+		if ((info->attr.mq_curmsgs > 1) && (!list_empty(&info->e_wait_q[sr].list)))
+			wait_exclusive(&(info->wait_q2[sr]), info);
+	}
+	/* We can wake up now - either all are sleeping or
+	 * queue is empty. */
+	if (!list_empty(&info->e_wait_q[sr].list))
+		wake_up_process((list_entry(info->e_wait_q[sr].list.prev, struct ext_wait_queue, list))->task);
+	/* for poll */
+	wake_up_interruptible(&(info->wait_q[sr]));
+}
+
+/*
+ * Invoked via ioctl to do the rest of work when creating new queue:
+ * set limits
+ */
+static int mq_create_ioctl(struct inode *ino, struct kern_mq_attr *u_attr)
+{
+	struct kern_mq_attr attr;
+	struct mqueue_inode_info *info = MQUEUE_I(ino);
+	int error = 0;
+
+	if (u_attr != NULL) {
+		if (copy_from_user(&attr, u_attr, sizeof(struct kern_mq_attr))) {
+			error = -EFAULT;
+			goto out1;
+		}
+		if (attr.mq_maxmsg == 0 || attr.mq_msgsize == 0
+		    || attr.mq_maxmsg > MQ_MAXMSG || attr.mq_msgsize > MQ_MSGSIZE) {
+			error = -EINVAL;
+			goto out1;
+		}
+        }
+
+	spin_lock(&info->lock);
+	if (info->attr.mq_maxmsg != 0) {
+		error = -EBADF;
+		goto out;
+	}
+	if (u_attr != NULL) {
+		info->attr.mq_maxmsg = attr.mq_maxmsg;
+		info->attr.mq_msgsize = attr.mq_msgsize;
+	} else {
+		info->attr.mq_maxmsg = MQ_MAXMSG;
+		info->attr.mq_msgsize = MQ_MSGSIZE;
+	}
+out:
+	spin_unlock(&info->lock);
+out1:
+	return error;
+}
+
+/* Auxiliary functions to manipulate messages heap */
+static inline void heap_insert(struct msg *ptr, struct mqueue_inode_info *info)
+{
+	int k, parent;
+
+	k = ++(info->attr.mq_curmsgs);
+	parent = k >> 1;
+	while (info->messages[parent]->msg_prio < ptr->msg_prio) {
+		info->messages[k] = info->messages[parent];
+		k = parent;
+		parent >>= 1;
+	}
+	info->messages[k] = ptr;
+}
+
+static inline struct msg *heap_get(struct mqueue_inode_info *info)
+{
+	int k = 1, child = 2;
+	struct msg *newtop, *retval;
+
+	retval = info->messages[1];
+	newtop = info->messages[info->attr.mq_curmsgs];
+	info->attr.mq_curmsgs--;
+	child = 2;
+	k = 1;
+
+	while (child <= info->attr.mq_curmsgs) {
+		if (child+1 <= info->attr.mq_curmsgs &&
+		    info->messages[child]->msg_prio <
+		    info->messages[child+1]->msg_prio)
+			child++;
+
+		if (info->messages[child]->msg_prio > newtop->msg_prio) {
+			info->messages[k] = info->messages[child];
+			k = child;
+			child <<= 1;
+			continue;
+		}
+		break;
+	}
+
+	if (info->attr.mq_curmsgs)
+		info->messages[k] = newtop;
+	return retval;
+}
+
+/*
+ * The next function is only to split too long mq_send_ioctl
+ */
+static inline void do_notify(struct mqueue_inode_info *info)
+{
+	struct siginfo sig_i;
+
+	/* notification
+	 * invoked when there is registered process and there isn't process
+	 * waiting synchronously for message AND state of queue changed from
+	 * empty to not empty*/
+	if (info->notify_task && list_empty(&info->e_wait_q[RECV].list)
+	    && info->attr.mq_curmsgs == 1) {
+		sig_i.si_signo = info->notify.sigev_signo;
+		sig_i.si_errno = 0;
+		sig_i.si_code = SI_MESGQ;
+		sig_i.si_value = info->notify.sigev_value;
+		sig_i.si_pid = current->pid;
+		sig_i.si_uid = current->uid;
+
+		/* sends signal */
+		if (info->notify.sigev_notify == SIGEV_SIGNAL) {
+			kill_proc_info(info->notify.sigev_signo,
+				       &sig_i, info->notify_task->pid);
+		} else  if (info->notify.sigev_notify == SIGEV_THREAD ||
+			    info->notify.sigev_notify == SIGEV_THREAD_ID)
+			send_sig_info(info->notify.sigev_signo, &sig_i, info->notify_task);
+		/* after notification unregisters process */
+		info->notify_task = NULL;
+		info->notify.sigev_signo = 0;
+		info->notify.sigev_notify = SIGEV_NONE;
+	}
+}
+
+static inline long prepare_timeout(struct ioctl_mq_sndrcv arg)
+{
+	struct timespec ts, nowts;
+	long timeout;
+
+	if (arg.timeout) {
+		if (copy_from_user(&ts, (struct timespec *) (long) arg.timeout,
+			sizeof(struct timespec)))
+			return -EFAULT;
+
+		if (ts.tv_nsec < 0 || ts.tv_sec < 0
+			|| ts.tv_nsec >= NSEC_PER_SEC)
+			return -EINVAL;
+		nowts = CURRENT_TIME;
+		/* first subtract as jiffies can't be too big */
+		ts.tv_sec -= nowts.tv_sec;
+		if (ts.tv_nsec < nowts.tv_nsec) {
+			ts.tv_nsec += NSEC_PER_SEC;
+			ts.tv_sec--;
+		}
+		ts.tv_nsec -= nowts.tv_nsec;
+		if (ts.tv_sec < 0)
+			return 0;
+
+		timeout = timespec_to_jiffies(&ts) + 1;
+	} else
+		return MAX_SCHEDULE_TIMEOUT;
+
+	return timeout;
+}
+
+
+int mq_send_ioctl(struct inode *ino, int oflag,
+		  struct ioctl_mq_sndrcv *u_arg)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(ino);
+	struct ioctl_mq_sndrcv arg;
+	struct msg *msg_ptr;
+	struct ext_wait_queue *wq_ptr;
+	char *msg_text_ptr;
+	long timeout;
+	int i, error;
+
+	i = error = 0;
+
+	if ((oflag & O_ACCMODE) == O_RDONLY)
+		return -EBADF;
+
+	if (copy_from_user(&arg, (void *) u_arg, sizeof(arg)))
+		return -EFAULT;
+
+	if (arg.msg_prio >= (unsigned long) MQ_PRIO_MAX)
+		return -EINVAL;
+
+	timeout = prepare_timeout(arg);
+	if (timeout < 0)
+		return timeout;
+
+	/* first try to allocate memory, before doing anything with
+	 * existing queues */
+	msg_ptr = kmalloc(sizeof(struct msg), GFP_KERNEL);
+	if (!msg_ptr)
+		return -ENOMEM;
+
+	msg_text_ptr = kmalloc(arg.msg_len, GFP_KERNEL);
+	if (!msg_text_ptr) {
+		error = -ENOMEM;
+		goto out_1free;
+	}
+
+	if (copy_from_user(msg_text_ptr, (char *) (long) arg.msg_ptr, arg.msg_len)) {
+		error = -EFAULT;
+		goto out_2free;
+	}
+
+	/* This memory may be unnecessary but we must alloc it here
+	 * because of spinlock. kfree is called in wq_remove(_last) */
+	wq_ptr = kmalloc(sizeof(struct ext_wait_queue), GFP_KERNEL);
+	if (wq_ptr == NULL) {
+		error = -ENOMEM;
+		goto out_2free;
+	}
+
+	spin_lock(&info->lock);
+
+	if ((oflag & O_NONBLOCK) != 0)
+		if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
+			error = -EAGAIN;
+			goto out_1unlock;
+		}
+
+	if (arg.msg_len > info->attr.mq_msgsize) {
+		error = -EMSGSIZE;
+		goto out_1unlock;
+	}
+
+	/* checks if queue is full -> I'm waiting as O_NONBLOCK isn't
+	 * set then. mq_receive wakes up only 1 process */
+	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
+		error = wq_sleep(info, SEND, timeout, wq_ptr);
+		if (error)
+			goto out_1unlock_nofree;
+	} else
+		kfree(wq_ptr);
+
+	spin_lock(&mq_lock);
+
+	if (msgs_size + arg.msg_len > MQ_MAXSYSSIZE) {
+		error = -ENOMEM;
+		goto out_2unlock;
+	}
+
+	msgs_size += arg.msg_len;
+
+	spin_unlock(&mq_lock);
+
+	/* adds message to the queue */
+	msg_ptr->msg_len = arg.msg_len;
+	msg_ptr->msg_prio = (unsigned int) arg.msg_prio;
+	msg_ptr->mtext = msg_text_ptr;
+
+	heap_insert(msg_ptr, info);
+
+	info->qsize += arg.msg_len;
+	do_notify(info);
+
+	/* after sending message we must wake up (ONLY 1 no matter which) */
+	/* process sleeping in wq_wakeup() */
+	wake_up(&(info->wait_q2[0]));
+
+	/* wakes up processes waiting for message */
+	wq_wakeup(info, RECV);
+
+	spin_unlock(&info->lock);
+	return 0;
+
+	/* I hate this goto convention... */
+out_2unlock:
+	spin_unlock(&mq_lock);
+	goto out_1unlock_nofree;
+out_1unlock:
+	kfree(wq_ptr);
+out_1unlock_nofree:
+	spin_unlock(&info->lock);
+out_2free:
+	kfree(msg_text_ptr);
+out_1free:
+	kfree(msg_ptr);
+	return error;
+}
+
+
+ssize_t mq_receive_ioctl(struct inode * ino, long oflag,
+			 struct ioctl_mq_sndrcv * u_arg)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(ino);
+	struct ioctl_mq_sndrcv arg;
+	struct msg *msg_ptr;
+	struct ext_wait_queue *wq_ptr;
+	ssize_t retval;
+	long timeout;
+
+	if ((oflag & O_ACCMODE) == O_WRONLY)
+		return -EBADF;
+
+	if (copy_from_user(&arg, u_arg, sizeof(struct ioctl_mq_sndrcv))) {
+		printk(KERN_ERR " mqueue fs: can't copy data from user space");
+		return -EFAULT;
+	}
+
+	timeout = prepare_timeout(arg);
+	if (timeout < 0)
+		return timeout;
+
+        /* The same as in mq_send_ioctl */
+	wq_ptr = kmalloc(sizeof(struct ext_wait_queue), GFP_KERNEL);
+	if (wq_ptr == NULL)
+		return -ENOMEM;
+
+	spin_lock(&info->lock);
+
+	/* checks if O_NONBLOCK is set and queue is empty */
+	if ((oflag & O_NONBLOCK) != 0)
+		if (info->attr.mq_curmsgs == 0) {
+			retval = -EAGAIN;
+			goto out_1unlock;
+		}
+
+	/* checks if buffer is big enough */
+	if (arg.msg_len < info->attr.mq_msgsize) {
+		retval = -EMSGSIZE;
+		goto out_unlock_only;
+	}
+
+	/* checks if queue is empty -> as O_NONBLOCK isn't set then
+	 * we must wait */
+	if (info->attr.mq_curmsgs == 0) {
+		retval = wq_sleep(info, RECV, timeout, wq_ptr);
+		if (retval < 0)
+			goto out_unlock_only;
+	} else
+		kfree(wq_ptr);
+
+	msg_ptr = heap_get(info);
+	retval = msg_ptr->msg_len;
+
+	/* decrease total space used by messages */
+	spin_lock(&mq_lock);
+	msgs_size -= retval;
+	spin_unlock(&mq_lock);
+	info->qsize -= retval;
+
+	/* after receive we can wakeup 1 process waiting in wq_wakeup */
+	wake_up(&(info->wait_q2[1]));
+	/* wakes up processes waiting for sending message */
+	wq_wakeup(info, SEND);
+
+	spin_unlock(&info->lock);
+
+	if (arg.msg_prio) {
+		if (put_user(msg_ptr->msg_prio, (long *) (long) arg.msg_prio)) {
+			retval = -EFAULT;
+			goto out_2free;
+		}
+        }
+	if (copy_to_user((char *) (long) arg.msg_ptr, msg_ptr->mtext, msg_ptr->msg_len))
+		retval = -EFAULT;
+
+out_2free:
+	kfree(msg_ptr->mtext);
+	kfree(msg_ptr);
+	return retval;
+out_1unlock:
+	kfree(wq_ptr);
+out_unlock_only:
+	spin_unlock(&info->lock);
+	return retval;
+}
+
+
+int mq_notify_ioctl(struct inode *ino,
+		    const struct sigevent *u_notification)
+{
+	struct sigevent notification;
+	struct mqueue_inode_info *info = MQUEUE_I(ino);
+	int error = 0;
+
+	if (u_notification != NULL)
+		if (copy_from_user(&notification, u_notification, sizeof(struct sigevent)))
+			return -EFAULT;
+
+	spin_lock(&info->lock);
+
+	if ((info->notify_task == current) && (u_notification == NULL ||
+		notification.sigev_notify == SIGEV_NONE)) {
+		info->notify_task = NULL;	/* remove notification */
+		info->notify.sigev_signo = 0;
+		info->notify.sigev_notify = SIGEV_NONE;
+	} else if (info->notify_task) {
+		error = -EBUSY;
+		goto out;
+	} else if (u_notification != NULL && notification.sigev_notify != SIGEV_NONE) {
+		/* add notification */
+		info->notify_task = current;
+		info->notify.sigev_signo = notification.sigev_signo;
+		info->notify.sigev_notify = notification.sigev_notify;
+		info->notify.sigev_value = notification.sigev_value;
+	}
+out:
+	spin_unlock(&info->lock);
+	return error;
+}
+
+int mq_getattr_ioctl(struct inode *ino, int oflag, struct kern_mq_attr *u_mqstat)
+{
+	struct kern_mq_attr attr;
+	struct mqueue_inode_info *info = MQUEUE_I(ino);
+
+	if (u_mqstat == NULL)
+		return -EINVAL;
+
+	spin_lock(&info->lock);
+
+	attr = info->attr;
+	attr.mq_flags = oflag;
+
+	spin_unlock(&info->lock);
+
+	if (copy_to_user(u_mqstat, &attr, sizeof(struct kern_mq_attr)))
+		return -EFAULT;
+	return 0;
+}
+
+inline int mq_dummy_ioctl(void)
+{
+	return 0;
+}
+
+/*
+*	IOCTL FUNCTION - demultiplexer for various mqueues operations
+*/
+
+static int mqueue_ioctl_file(struct inode *inode, struct file *filp,
+			     unsigned int cmd, unsigned long arg)
+{
+	int ret = -ENOTTY;
+
+	unlock_kernel();
+
+	switch (cmd) {
+	case MQ_IOC_CREATE:
+		ret = mq_create_ioctl(inode, (struct kern_mq_attr *) arg);
+		break;
+	case MQ_IOC_SEND:
+		ret = mq_send_ioctl(inode, filp->f_flags, (struct ioctl_mq_sndrcv *) arg);
+		break;
+	case MQ_IOC_RECEIVE:
+		ret = mq_receive_ioctl(inode, filp->f_flags, (struct ioctl_mq_sndrcv *) arg);
+		break;
+	case MQ_IOC_NOTIFY:
+		ret = mq_notify_ioctl(inode, (struct sigevent *) arg);
+		break;
+	case MQ_IOC_GETATTR:
+		ret = mq_getattr_ioctl(inode, filp->f_flags, (struct kern_mq_attr *) arg);
+		break;
+	case MQ_IOC_CLOSE:
+	case MQ_IOC_SETATTR:
+		ret = mq_dummy_ioctl();
+		break;
+	}
+
+	lock_kernel();
+	return ret;
+}
+
+static struct inode_operations mqueue_dir_inode_operations = {
+	.lookup = mqueue_lookup,
+	.create = mqueue_create,
+	.unlink = mqueue_unlink,
+};
+
+static struct file_operations mqueue_file_operations = {
+	.ioctl = mqueue_ioctl_file,
+	.release = mqueue_release_file,
+	.poll = mqueue_poll_file,
+	.read = mqueue_read_file,
+};
+
+static struct super_operations mqueue_super_ops = {
+	.alloc_inode = mqueue_alloc_inode,
+	.destroy_inode = mqueue_destroy_inode,
+	.statfs = simple_statfs,
+	.delete_inode = mqueue_delete_inode,
+	.drop_inode = generic_delete_inode,
+};
+
+static struct file_system_type mqueue_fs_type = {
+	.owner = THIS_MODULE,
+	.name = "mqueue",
+	.get_sb = mqueue_get_sb,
+	.kill_sb = kill_litter_super,
+};
+
+
+static int __init init_mqueue_fs(void)
+{
+	int error;
+	error = init_inode_cache();
+
+	if (error) {
+		printk(KERN_ERR "Could not init inode cache for mqueue filesystem\n");
+		return error;
+	}
+
+	error = register_filesystem(&mqueue_fs_type);
+	if (error) {
+		printk(KERN_ERR "Could not register mqueue filesystem\n");
+		goto out_inodecache;
+	}
+
+	/* internal initialization - not common for vfs */
+	msgs_size = 0;
+	queues_count = 0;
+	spin_lock_init(&mq_lock);
+
+	return 0;
+
+out_inodecache:
+	destroy_inode_cache();
+	return error;
+}
+
+static void __exit exit_mqueue_fs(void)
+{
+	unregister_filesystem(&mqueue_fs_type);
+	destroy_inode_cache();
+}
+
+module_init(init_mqueue_fs)
+module_exit(exit_mqueue_fs)
+
+MODULE_LICENSE("GPL");


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [RFC][PATCH] Posix Message Queues
  2003-07-14 20:16 Manfred Spraul
@ 2003-07-14 20:39 ` Alan Cox
  0 siblings, 0 replies; 3+ messages in thread
From: Alan Cox @ 2003-07-14 20:39 UTC (permalink / raw)
  To: Manfred Spraul
  Cc: Michal Wronski, Linux Kernel Mailing List, Christoph Hellwig

On Llu, 2003-07-14 at 21:16, Manfred Spraul wrote:
> Hi Michal,
> 
> You've implemented mq_open() in user space by combining open()+ioctl() 
> syscalls. I think it's racy:
> 
> What if two processes call
> {
>     fd = mq_open("dummy",O_CREAT,0777,{.mq_maxmsg=10000});
>     mq_send = mq_send(fd,buf,10000,0);
> }
> 
> I think setting the queue options and creating a new queue must be 
> atomic, i.e. we need a new syscall.

O_EXCL lets you know if you are the real creator. That means you can
create it 000, fix it up, fchmod it and go


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [RFC][PATCH] Posix Message Queues
@ 2003-07-14 20:16 Manfred Spraul
  2003-07-14 20:39 ` Alan Cox
  0 siblings, 1 reply; 3+ messages in thread
From: Manfred Spraul @ 2003-07-14 20:16 UTC (permalink / raw)
  To: Michal Wronski; +Cc: linux-kernel, Christoph Hellwig

Hi Michal,

You've implemented mq_open() in user space by combining open()+ioctl() 
syscalls. I think it's racy:

What if two processes call
{
    fd = mq_open("dummy",O_CREAT,0777,{.mq_maxmsg=10000});
    mq_send = mq_send(fd,buf,10000,0);
}

I think setting the queue options and creating a new queue must be 
atomic, i.e. we need a new syscall.

Could you replace the printk's with Dprintk or something like that? User 
space misbehaviour such as bad pointers should not generate printk messages.

--
    Manfred



^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2003-07-14 20:28 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-07-14 17:43 [RFC][PATCH] Posix Message Queues Michal Wronski
2003-07-14 20:16 Manfred Spraul
2003-07-14 20:39 ` Alan Cox

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