Staging: batman-adv: add routing debug log accessible via debugfs

All routing debug messages are saved in a ring buffer that can be
read via the debugfs file "log".
Note that CONFIG_BATMAN_ADV_DEBUG must be activated to have the
debug logs compiled in.

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 190 insertions, 0 deletions

diff --git a/drivers/staging/batman-adv/bat_debugfs.c b/drivers/staging/batman-adv/bat_debugfs.c
index fafca9f..f818d5e 100644
--- a/drivers/staging/batman-adv/bat_debugfs.c
+++ b/drivers/staging/batman-adv/bat_debugfs.c
@@ -31,6 +31,193 @@
 
 static struct dentry *bat_debugfs;
 
+#ifdef CONFIG_BATMAN_ADV_DEBUG
+#define LOG_BUFF_MASK (log_buff_len-1)
+#define LOG_BUFF(idx) (debug_log->log_buff[(idx) & LOG_BUFF_MASK])
+
+static int log_buff_len = LOG_BUF_LEN;
+
+static void emit_log_char(struct debug_log *debug_log, char c)
+{
+	LOG_BUFF(debug_log->log_end) = c;
+	debug_log->log_end++;
+
+	if (debug_log->log_end - debug_log->log_start > log_buff_len)
+		debug_log->log_start = debug_log->log_end - log_buff_len;
+}
+
+static int fdebug_log(struct debug_log *debug_log, char *fmt, ...)
+{
+	int printed_len;
+	va_list args;
+	static char debug_log_buf[256];
+	char *p;
+	unsigned long flags;
+
+	if (!debug_log)
+		return 0;
+
+	spin_lock_irqsave(&debug_log->lock, flags);
+	va_start(args, fmt);
+	printed_len = vscnprintf(debug_log_buf, sizeof(debug_log_buf),
+				 fmt, args);
+	va_end(args);
+
+	for (p = debug_log_buf; *p != 0; p++)
+		emit_log_char(debug_log, *p);
+
+	spin_unlock_irqrestore(&debug_log->lock, flags);
+
+	wake_up(&debug_log->queue_wait);
+
+	return 0;
+}
+
+int debug_log(struct bat_priv *bat_priv, char *fmt, ...)
+{
+	va_list args;
+	char tmp_log_buf[256];
+
+	va_start(args, fmt);
+	vscnprintf(tmp_log_buf, sizeof(tmp_log_buf), fmt, args);
+	fdebug_log(bat_priv->debug_log, "[%10u] %s",
+		   (jiffies / HZ), tmp_log_buf);
+	va_end(args);
+
+	return 0;
+}
+
+static int log_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	inc_module_count();
+	return 0;
+}
+
+static int log_release(struct inode *inode, struct file *file)
+{
+	dec_module_count();
+	return 0;
+}
+
+static ssize_t log_read(struct file *file, char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	struct bat_priv *bat_priv = (struct bat_priv *)file->private_data;
+	struct debug_log *debug_log = bat_priv->debug_log;
+	int error, i = 0;
+	char c;
+	unsigned long flags;
+
+	if ((file->f_flags & O_NONBLOCK) &&
+	    !(debug_log->log_end - debug_log->log_start))
+		return -EAGAIN;
+
+	if ((!buf) || (count < 0))
+		return -EINVAL;
+
+	if (count == 0)
+		return 0;
+
+	if (!access_ok(VERIFY_WRITE, buf, count))
+		return -EFAULT;
+
+	error = wait_event_interruptible(debug_log->queue_wait,
+				(debug_log->log_start - debug_log->log_end));
+
+	if (error)
+		return error;
+
+	spin_lock_irqsave(&debug_log->lock, flags);
+
+	while ((!error) && (i < count) &&
+	       (debug_log->log_start != debug_log->log_end)) {
+		c = LOG_BUFF(debug_log->log_start);
+
+		debug_log->log_start++;
+
+		spin_unlock_irqrestore(&debug_log->lock, flags);
+
+		error = __put_user(c, buf);
+
+		spin_lock_irqsave(&debug_log->lock, flags);
+
+		buf++;
+		i++;
+
+	}
+
+	spin_unlock_irqrestore(&debug_log->lock, flags);
+
+	if (!error)
+		return i;
+
+	return error;
+}
+
+static unsigned int log_poll(struct file *file, poll_table *wait)
+{
+	struct bat_priv *bat_priv = (struct bat_priv *)file->private_data;
+	struct debug_log *debug_log = bat_priv->debug_log;
+
+	poll_wait(file, &debug_log->queue_wait, wait);
+
+	if (debug_log->log_end - debug_log->log_start)
+		return POLLIN | POLLRDNORM;
+
+	return 0;
+}
+
+static const struct file_operations log_fops = {
+	.open           = log_open,
+	.release        = log_release,
+	.read           = log_read,
+	.poll           = log_poll,
+};
+
+static int debug_log_setup(struct bat_priv *bat_priv)
+{
+	struct dentry *d;
+
+	if (!bat_priv->debug_dir)
+		goto err;
+
+	bat_priv->debug_log = kzalloc(sizeof(struct debug_log), GFP_ATOMIC);
+	if (!bat_priv->debug_log)
+		goto err;
+
+	spin_lock_init(&bat_priv->debug_log->lock);
+	init_waitqueue_head(&bat_priv->debug_log->queue_wait);
+
+	d = debugfs_create_file("log", S_IFREG | S_IRUSR,
+				bat_priv->debug_dir, bat_priv, &log_fops);
+	if (d)
+		goto err;
+
+	return 0;
+
+err:
+	return 1;
+}
+
+static void debug_log_cleanup(struct bat_priv *bat_priv)
+{
+	kfree(bat_priv->debug_log);
+	bat_priv->debug_log = NULL;
+}
+#else /* CONFIG_BATMAN_ADV_DEBUG */
+static int debug_log_setup(struct bat_priv *bat_priv)
+{
+	bat_priv->debug_log = NULL;
+	return 0;
+}
+
+static void debug_log_cleanup(struct bat_priv *bat_priv)
+{
+	return;
+}
+#endif
+
 static int originators_open(struct inode *inode, struct file *file)
 {
 	struct net_device *net_dev = (struct net_device *)inode->i_private;
@@ -114,6 +301,7 @@ int debugfs_add_meshif(struct net_device *dev)
 		goto out;
 
 	bat_socket_setup(bat_priv);
+	debug_log_setup(bat_priv);
 
 	for (bat_debug = mesh_debuginfos; *bat_debug; ++bat_debug) {
 		file = debugfs_create_file(((*bat_debug)->attr).name,
@@ -143,6 +331,8 @@ void debugfs_del_meshif(struct net_device *dev)
 {
 	struct bat_priv *bat_priv = netdev_priv(dev);
 
+	debug_log_cleanup(bat_priv);
+
 	if (bat_debugfs) {
 		debugfs_remove_recursive(bat_priv->debug_dir);
 		bat_priv->debug_dir = NULL;