diff options
Diffstat (limited to 'drivers/usb/serial/usb-serial.c')
| -rw-r--r-- | drivers/usb/serial/usb-serial.c | 36 |
1 files changed, 31 insertions, 5 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index bd7581b3a48a..99188c92068b 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -32,6 +32,7 @@ #include <linux/mutex.h> #include <linux/list.h> #include <linux/uaccess.h> +#include <linux/serial.h> #include <linux/usb.h> #include <linux/usb/serial.h> #include "pl2303.h" @@ -184,6 +185,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp) struct usb_serial_port *port; unsigned int portNumber; int retval = 0; + int first = 0; dbg("%s", __func__); @@ -223,7 +225,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp) /* If the console is attached, the device is already open */ if (port->port.count == 1 && !port->console) { - + first = 1; /* lock this module before we call it * this may fail, which means we must bail out, * safe because we are called with BKL held */ @@ -246,13 +248,21 @@ static int serial_open (struct tty_struct *tty, struct file *filp) if (retval) goto bailout_interface_put; mutex_unlock(&serial->disc_mutex); + set_bit(ASYNCB_INITIALIZED, &port->port.flags); } mutex_unlock(&port->mutex); /* Now do the correct tty layer semantics */ retval = tty_port_block_til_ready(&port->port, tty, filp); - if (retval == 0) + if (retval == 0) { + if (!first) + usb_serial_put(serial); return 0; - + } + mutex_lock(&port->mutex); + if (first == 0) + goto bailout_mutex_unlock; + /* Undo the initial port actions */ + mutex_lock(&serial->disc_mutex); bailout_interface_put: usb_autopm_put_interface(serial->interface); bailout_module_put: @@ -340,6 +350,22 @@ static void serial_close(struct tty_struct *tty, struct file *filp) dbg("%s - port %d", __func__, port->number); + /* FIXME: + This leaves a very narrow race. Really we should do the + serial_do_free() on tty->shutdown(), but tty->shutdown can + be called from IRQ context and serial_do_free can sleep. + + The right fix is probably to make the tty free (which is rare) + and thus tty->shutdown() occur via a work queue and simplify all + the drivers that use it. + */ + if (tty_hung_up_p(filp)) { + /* serial_hangup already called serial_down at this point. + Another user may have already reopened the port but + serial_do_free is refcounted */ + serial_do_free(port); + return; + } if (tty_port_close_start(&port->port, tty, filp) == 0) return; @@ -355,7 +381,8 @@ static void serial_hangup(struct tty_struct *tty) struct usb_serial_port *port = tty->driver_data; serial_do_down(port); tty_port_hangup(&port->port); - serial_do_free(port); + /* We must not free port yet - the USB serial layer depends on it's + continued existence */ } static int serial_write(struct tty_struct *tty, const unsigned char *buf, @@ -394,7 +421,6 @@ static int serial_chars_in_buffer(struct tty_struct *tty) struct usb_serial_port *port = tty->driver_data; dbg("%s = port %d", __func__, port->number); - WARN_ON(!port->port.count); /* if the device was unplugged then any remaining characters fell out of the connector ;) */ if (port->serial->disconnected) |