Commit e1fdd5b2 authored Mar 30, 2017 by Johan Hovold

USB: serial: drop obsolete open-race workaround



Commit a65a6f14 ("USB: serial: fix race between probe and open")
fixed a race between probe and open, which could lead to crashes when a
not yet fully initialised port was being opened.

This race was later incidentally closed by commit 7e73eca6 ("TTY:
move cdev_add to tty_register_device") which moved character-device
registration from tty_register_driver to tty_register_device, which
isn't called until the port has been fully set up.

Remove the now redundant workaround which had the negative side effect
of not allowing a port to be opened immediately after user space had
been notified of a new tty device.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

parent bc242fc1

drivers/usb/serial/usb-serial.c

+0 −8

Original line number	Diff line number	Diff line
		@@ -996,12 +996,6 @@ static int usb_serial_probe(struct usb_interface *interface,
		serial->attached = 1;
		}

		/* Avoid race with tty_open and serial_install by setting the
		* disconnected flag and not clearing it until all ports have been
		* registered.
		*/
		serial->disconnected = 1;

		if (allocate_minors(serial, num_ports)) {
		dev_err(ddev, "No more free serial minor numbers\n");
		goto probe_error;
		@@ -1019,8 +1013,6 @@ static int usb_serial_probe(struct usb_interface *interface,
		dev_err(ddev, "Error registering port device, continuing\n");
		}

		serial->disconnected = 0;

		if (num_ports > 0)
		usb_serial_console_init(serial->port[0]->minor);
		exit: