1 files changed, 228 insertions, 0 deletions
diff --git a/runtime/transport/control.c b/runtime/transport/control.c
new file mode 100644
index 00000000..1699f54d
--- /dev/null
+++ b/runtime/transport/control.c
@@ -0,0 +1,228 @@
+/*
+ *  stp-control - stp control channel
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2005
+ * Copyright (C) Redhat Inc, 2005
+ *
+ */
+
+/** @file control.c
+ * @brief Systemtap control channel functions
+ */
+
+/** @addtogroup transport Transport Functions
+ * @{
+ */
+
+#include <linux/module.h>
+#include <linux/hash.h>
+#include "control.h"
+#include "netlink.h"
+
+/* the control channel */
+struct sock *stp_control;
+
+/* the command handlers hash table */
+static struct hlist_head *handlers;
+
+/* protection for the handlers table */
+static DEFINE_SPINLOCK(handlers_lock);
+
+/**
+ *	_stp_lookup_handler - look up the command handler in the handlers table
+ *	@pid: the pid to find the corresponding handler of
+ *
+ *	Returns the pointer to the cmd_handler struct, NULL if not
+ *	found.
+ *
+ *	NOTE: the handlers_lock must be held when calling this function
+ */
+static struct cmd_handler *_stp_lookup_handler(int pid)
+{
+	struct hlist_node *node;
+	struct cmd_handler *handler;
+	unsigned long key = hash_long((unsigned long)pid, HANDLER_SHIFT);
+	struct hlist_head *head = &handlers[key];
+	
+	hlist_for_each(node, head) {
+		handler = hlist_entry(node, struct cmd_handler, hlist);
+		if (handler->pid == pid) {
+			return handler;
+			break;
+		}
+	}
+	
+	return NULL;
+}
+
+/**
+ *	_stp_handler_find - find the command handler for a given pid
+ *	@pid: the pid to find the corresponding handler of
+ *
+ *	Returns the pointer to the command handler callback, NULL if
+ *	not found.
+ */
+static int (*_stp_handler_find(int pid))(int, int, void *)
+{
+	struct cmd_handler *cmd_handler;
+
+	spin_lock(&handlers_lock);
+	cmd_handler = _stp_lookup_handler(pid);
+	spin_unlock(&handlers_lock);
+	
+	if (cmd_handler)
+		return cmd_handler->handler;
+	
+	return NULL;
+}
+
+/**
+ *	_stp_ctrl_register - register a command handler for a pid
+ *	@pid: the pid to unregister
+ *	@cmd_handler: the callback function to be called to handle commands
+ *
+ *	Adds a pid's command handler to the handler table.  The
+ *	command handler will be called to handle commands from the
+ *	daemon with the given pid.  Should be called at probe module
+ *	initialization before any commands are sent by the daemon.
+ */
+int _stp_ctrl_register(int pid,
+		       int (*cmd_handler) (int pid, int cmd, void *data))
+{
+	unsigned long key = hash_long((unsigned long)pid, HANDLER_SHIFT);
+	struct hlist_head *head = &handlers[key];
+	struct cmd_handler *handler;
+
+	spin_lock(&handlers_lock);
+	handler = _stp_lookup_handler(pid);
+	spin_unlock(&handlers_lock);
+
+	if (handler)
+		return -EBUSY;
+
+	handler = kmalloc(sizeof(struct cmd_handler), GFP_KERNEL);
+	if (!handler)
+		return -ENOMEM;
+	handler->pid = pid;
+	handler->handler = cmd_handler;
+	INIT_HLIST_NODE(&handler->hlist);
+
+	spin_lock(&handlers_lock);
+	hlist_add_head(&handler->hlist, head);
+	spin_unlock(&handlers_lock);
+
+	return 0;
+}
+
+/**
+ *	_stp_ctrl_unregister - unregister a pid's command handler
+ *	@pid: the pid to unregister
+ *
+ *	Removes the pid's handler from the handler table.  Should be
+ *	called when the daemon is no longer sending commands.
+ */
+void _stp_ctrl_unregister(int pid)
+{
+	struct cmd_handler *handler;
+	
+	spin_lock(&handlers_lock);
+	handler = _stp_lookup_handler(pid);
+	if (handler) {
+		hlist_del(&handler->hlist);
+		kfree(handler);
+	}
+	spin_unlock(&handlers_lock);
+}
+
+/**
+ *	_stp_ctrl_send - send data over the control channel
+ *	@type: the type of data being sent
+ *	@data: the data
+ *	@len: the data length
+ *	@pid: the pid to send the data to
+ *
+ *	Returns the result of the transport's send function.
+ */
+int _stp_ctrl_send(int type, void *data, int len, int pid)
+{
+	return _stp_netlink_send(type, data, len, pid);
+}
+
+/**
+ *	_stp_ctrl_handler - control channel command dispatcher
+ *	@pid: the pid the command is from
+ *	@cmd: the command
+ *	@data: command-specific data
+ *
+ *	Returns the result from the pid's command handler, 0 if the
+ *	command was handled, non-zero otherwise.
+ */
+static int _stp_ctrl_handler(int pid, int cmd, void *data)
+{
+	int (*cmd_handler) (int, int, void *);
+
+	cmd_handler = _stp_handler_find(pid);
+	if (!cmd_handler)
+		return -EINVAL;
+	
+	return cmd_handler(pid, cmd, data);
+}
+
+/**
+ *	_stp_ctrl_init - module init function
+ */
+static int __init _stp_ctrl_init(void)
+{
+	int i;
+
+	handlers = kmalloc(sizeof(struct hlist_head) * HANDLER_SLOTS, GFP_KERNEL);
+	if (!handlers)
+		return -ENOMEM;
+	
+	for (i = 0; i < HANDLER_SLOTS; i++)
+		INIT_HLIST_HEAD(&handlers[i]);
+
+	stp_control = _stp_netlink_open(NETLINK_USERSOCK, _stp_ctrl_handler);
+	if (!stp_control) {
+		printk ("stp_ctrl: couldn't open netlink socket\n");
+		kfree(handlers);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/**
+ *	_stp_ctrl_exit - module exit function
+ */
+static void _stp_ctrl_exit(void)
+{
+	_stp_netlink_close(stp_control);
+	kfree(handlers);
+}
+
+module_init(_stp_ctrl_init);
+module_exit(_stp_ctrl_exit);
+
+EXPORT_SYMBOL_GPL(_stp_ctrl_register);
+EXPORT_SYMBOL_GPL(_stp_ctrl_unregister);
+EXPORT_SYMBOL_GPL(_stp_ctrl_send);
+
+MODULE_DESCRIPTION("SystemTap control channel");
+MODULE_AUTHOR("Tom Zanussi <zanussi@us.ibm.com>");
+MODULE_LICENSE("GPL");
+