1 files changed, 275 insertions, 0 deletions
diff --git a/runtime/transport/control.c b/runtime/transport/control.c
new file mode 100644
index 00000000..3ad3e309
--- /dev/null
+++ b/runtime/transport/control.c
@@ -0,0 +1,275 @@
+/* -*- linux-c -*-
+ *
+ * debugfs control channel
+ * Copyright (C) 2007 Red Hat Inc.
+ *
+ * This file is part of systemtap, and is free software.  You can
+ * redistribute it and/or modify it under the terms of the GNU General
+ * Public License (GPL); either version 2, or (at your option) any
+ * later version.
+ */
+
+#define STP_DEFAULT_BUFFERS 20
+static int _stp_current_buffers = STP_DEFAULT_BUFFERS;
+
+static struct list_head _stp_ready_q;
+static struct list_head _stp_pool_q;
+spinlock_t _stp_pool_lock = SPIN_LOCK_UNLOCKED;
+spinlock_t _stp_ready_lock = SPIN_LOCK_UNLOCKED;
+
+static ssize_t _stp_ctl_write_cmd (struct file *file, const char __user *buf,
+				    size_t count, loff_t *ppos)
+{
+	int type;
+
+	if (count < sizeof(int))
+		return 0;
+
+	if (get_user(type, (int __user *)buf))
+		return -EFAULT;
+
+	//kbug ("count:%d type:%d\n", count, type);
+
+	if (type == STP_SYMBOLS) {
+		count -= sizeof(long);
+		buf += sizeof(long);
+	} else {
+		count -= sizeof(int);
+		buf += sizeof(int);
+	}
+
+	switch (type) {
+	case STP_START:
+	{
+		struct _stp_msg_start st;
+		if (count < sizeof(st))
+			return 0;
+		if (copy_from_user (&st, buf, sizeof(st)))
+			return -EFAULT;
+		_stp_handle_start (&st);
+		break;
+	}
+
+	case STP_SYMBOLS:
+		count = _stp_do_symbols(buf, count);
+		break;
+	case STP_MODULE:
+		count = _stp_do_module(buf, count);
+		break;
+	case STP_EXIT:
+		_stp_exit_flag = 1;
+		break;
+	default:
+		errk ("invalid command type %d\n", type);
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+struct _stp_buffer {
+	struct list_head list;
+	int len;
+	int type;
+	char buf[STP_BUFFER_SIZE];
+};
+
+static DECLARE_WAIT_QUEUE_HEAD(_stp_ctl_wq);
+
+#ifdef DEBUG
+static void _stp_ctl_write_dbug (int type, void *data, int len)
+{
+	char buf[64];
+	switch (type) {
+	case STP_START:
+		printk("_stp_ctl_write: sending STP_START\n");
+		break;
+	case STP_EXIT:
+		printk("_stp_ctl_write: sending STP_EXIT\n");
+		break;
+	case STP_OOB_DATA:
+		snprintf(buf, sizeof(buf), "%s", (char *)data); 
+		printk("_stp_ctl_write: sending %d bytes of STP_OOB_DATA: %s\n", len, buf);
+		break;
+	case STP_SYSTEM:
+		snprintf(buf, sizeof(buf), "%s", (char *)data); 
+		printk("_stp_ctl_write: sending STP_SYSTEM: %s\n", buf);
+		break;
+	case STP_SYMBOLS:
+		printk("_stp_ctl_write: sending STP_SYMBOLS\n");
+		break;
+	case STP_MODULE:
+		printk("_stp_ctl_write: sending STP_MODULE\n");
+		break;
+	case STP_TRANSPORT:
+		printk("_stp_ctl_write: sending STP_TRANSPORT\n");
+		break;
+	default:
+		printk("_stp_ctl_write: ERROR: unknown message type: %d\n", type);
+		break;
+	}
+}
+#endif
+
+static int _stp_ctl_write (int type, void *data, int len)
+{
+	struct _stp_buffer *bptr;
+	unsigned long flags;
+	unsigned numtrylock;
+
+#ifdef DEBUG
+	_stp_ctl_write_dbug(type, data, len);
+#endif
+	numtrylock = 0;
+	while (!spin_trylock_irqsave (&_stp_pool_lock, flags) && (++numtrylock < MAXTRYLOCK)) 
+		ndelay (TRYLOCKDELAY);
+	if (unlikely (numtrylock >= MAXTRYLOCK)) 
+		return 0;
+
+	if (list_empty(&_stp_pool_q)) {
+		spin_unlock_irqrestore(&_stp_pool_lock, flags); 
+		return -1;
+	}
+
+	/* get the next buffer from the pool */
+	bptr = (struct _stp_buffer *)_stp_pool_q.next;
+	list_del_init(&bptr->list);
+	spin_unlock_irqrestore(&_stp_pool_lock, flags);
+
+	bptr->type = type;
+	memcpy (bptr->buf, data, len);
+	bptr->len = len;
+	
+	/* put it on the pool of ready buffers */
+	numtrylock = 0;
+	while (!spin_trylock_irqsave (&_stp_ready_lock, flags) && (++numtrylock < MAXTRYLOCK)) 
+		ndelay (TRYLOCKDELAY);
+	if (unlikely (numtrylock >= MAXTRYLOCK))
+		return 0;
+	list_add_tail(&bptr->list, &_stp_ready_q);
+	spin_unlock_irqrestore(&_stp_ready_lock, flags);
+
+	return len;
+}
+
+/* send commands with timeout and retry */
+static int _stp_ctl_send (int type, void *data, int len)
+{
+	int err, trylimit = 50;
+	kbug("ctl_send: type=%d len=%d\n", type, len);
+	while ((err = _stp_ctl_write(type, data, len)) < 0 && trylimit--)
+		msleep (5);
+	kbug("returning %d\n", err);
+	return err;
+}
+
+static ssize_t
+_stp_ctl_read_cmd (struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct _stp_buffer *bptr;
+	int len;
+	unsigned long flags;
+
+	/* FIXME FIXME FIXME. assuming count is large enough to hold buffer!! */
+
+	/* wait for nonempty ready queue */
+	spin_lock_irqsave(&_stp_ready_lock, flags);
+	while (list_empty(&_stp_ready_q)) {
+		spin_unlock_irqrestore(&_stp_ready_lock, flags);
+		if (file->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+		if (wait_event_interruptible(_stp_ctl_wq, !list_empty(&_stp_ready_q)))
+			return -ERESTARTSYS;
+		spin_lock_irqsave(&_stp_ready_lock, flags);
+	}
+  
+	/* get the next buffer off the ready list */
+	bptr = (struct _stp_buffer *)_stp_ready_q.next;
+	list_del_init(&bptr->list);
+	spin_unlock_irqrestore(&_stp_ready_lock, flags);
+
+	/* write it out */
+	len = bptr->len + 4;
+	if (copy_to_user(buf, &bptr->type, len)) {
+		/* now what?  We took it off the queue then failed to send it */
+		/* we can't put it back on the queue because it will likely be out-of-order */
+		/* fortunately this should never happen */
+		/* FIXME need to mark this as a transport failure */
+		return -EFAULT;
+	}
+
+	/* put it on the pool of free buffers */
+	spin_lock_irqsave(&_stp_pool_lock, flags);
+	list_add_tail(&bptr->list, &_stp_pool_q);
+	spin_unlock_irqrestore(&_stp_pool_lock, flags);
+
+	return len;
+}
+
+
+static struct file_operations _stp_ctl_fops_cmd = {
+	.owner = THIS_MODULE,
+	.read = _stp_ctl_read_cmd,
+	.write = _stp_ctl_write_cmd,
+};
+
+static struct dentry *_stp_cmd_file = NULL;
+
+static int _stp_register_ctl_channel (void)
+{
+	int i;
+	struct list_head *p, *tmp;
+	char buf[32];
+
+	if (_stp_utt == NULL) {
+		errk("_expected _stp_utt to be set.\n");
+		return -1;
+	}
+
+	INIT_LIST_HEAD(&_stp_ready_q);
+	INIT_LIST_HEAD(&_stp_pool_q);
+
+	/* allocate buffers */
+	for (i = 0; i < STP_DEFAULT_BUFFERS; i++) {
+		p = (struct list_head *)kmalloc(sizeof(struct _stp_buffer),STP_ALLOC_FLAGS);
+		// printk("allocated buffer at %lx\n", (long)p);
+		if (!p)
+			goto err0;
+		_stp_allocated_net_memory += sizeof(struct _stp_buffer);
+		list_add (p, &_stp_pool_q);
+	}
+	
+
+	/* create [debugfs]/systemtap_[pid]/cmd  */
+	_stp_cmd_file = debugfs_create_file("cmd", 0444, _stp_utt->utt_tree_root, NULL, &_stp_ctl_fops_cmd);
+	if (_stp_cmd_file == NULL) 
+		goto err0;
+
+	return 0;
+
+err0:
+	list_for_each_safe(p, tmp, &_stp_pool_q) {
+		list_del(p);
+		kfree(p);
+	}
+	errk ("Error creating systemtap debugfs entries.\n");
+	return -1;
+}
+
+
+static void _stp_unregister_ctl_channel (void)
+{
+	struct list_head *p, *tmp;
+	if (_stp_cmd_file) debugfs_remove(_stp_cmd_file);
+
+	/* free memory pools */
+	list_for_each_safe(p, tmp, &_stp_pool_q) {
+		list_del(p);
+		kfree(p);
+	}
+	list_for_each_safe(p, tmp, &_stp_ready_q) {
+		list_del(p);
+		kfree(p);
+	}
+}
+