USB: serial: fix port attribute-creation race

Fix attribute-creation race with userspace by using the port device
groups field to create the port attributes.

Also use %u when printing the port number, which is unsigned, even
though we do not currently support more than 128 ports per device.

Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Greg Kroah-Hartman <greg@kroah.com>

diff --git a/drivers/usb/serial/bus.c b/drivers/usb/serial/bus.c
index 6f91eb9ae81a44ebd3b8eb530594e3d3481e0d65..b53a2869222601763890747db297480b0318d735 100644 (file)
--- a/drivers/usb/serial/bus.c
+++ b/drivers/usb/serial/bus.c
@@ -38,15 +38,6 @@ static int usb_serial_device_match(struct device *dev,
        return 0;
 }
 
-static ssize_t port_number_show(struct device *dev,
-                               struct device_attribute *attr, char *buf)
-{
-       struct usb_serial_port *port = to_usb_serial_port(dev);
-
-       return sprintf(buf, "%d\n", port->port_number);
-}
-static DEVICE_ATTR_RO(port_number);
-
 static int usb_serial_device_probe(struct device *dev)
 {
        struct usb_serial_driver *driver;
@@ -73,18 +64,10 @@ static int usb_serial_device_probe(struct device *dev)
                        goto exit_with_autopm;
        }
 
-       retval = device_create_file(dev, &dev_attr_port_number);
-       if (retval) {
-               if (driver->port_remove)
-                       driver->port_remove(port);
-               goto exit_with_autopm;
-       }
-
        minor = port->minor;
        tty_dev = tty_register_device(usb_serial_tty_driver, minor, dev);
        if (IS_ERR(tty_dev)) {
                retval = PTR_ERR(tty_dev);
-               device_remove_file(dev, &dev_attr_port_number);
                if (driver->port_remove)
                        driver->port_remove(port);
                goto exit_with_autopm;
@@ -123,8 +106,6 @@ static int usb_serial_device_remove(struct device *dev)
        minor = port->minor;
        tty_unregister_device(usb_serial_tty_driver, minor);
 
-       device_remove_file(&port->dev, &dev_attr_port_number);
-
        driver = port->serial->type;
        if (driver->port_remove)
                retval = driver->port_remove(port);

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 19842370a07f93cdc7dd1992c29879389f80eecb..529066bbc7e81be1bb67e398f58425febef6a8eb 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -687,6 +687,21 @@ static void serial_port_dtr_rts(struct tty_port *port, int on)
                drv->dtr_rts(p, on);
 }
 
+static ssize_t port_number_show(struct device *dev,
+                               struct device_attribute *attr, char *buf)
+{
+       struct usb_serial_port *port = to_usb_serial_port(dev);
+
+       return sprintf(buf, "%u\n", port->port_number);
+}
+static DEVICE_ATTR_RO(port_number);
+
+static struct attribute *usb_serial_port_attrs[] = {
+       &dev_attr_port_number.attr,
+       NULL
+};
+ATTRIBUTE_GROUPS(usb_serial_port);
+
 static const struct tty_port_operations serial_port_ops = {
        .carrier_raised         = serial_port_carrier_raised,
        .dtr_rts                = serial_port_dtr_rts,
@@ -902,6 +917,7 @@ static int usb_serial_probe(struct usb_interface *interface,
                port->dev.driver = NULL;
                port->dev.bus = &usb_serial_bus_type;
                port->dev.release = &usb_serial_port_release;
+               port->dev.groups = usb_serial_port_groups;
                device_initialize(&port->dev);
        }