tty: Bring the usb tty port structure into more use

This allows us to clean stuff up, but is probably also going to cause
some app breakage with buggy apps as we now implement proper POSIX behaviour
for USB ports matching all the other ports. This does also mean other apps
that break on USB will now work properly.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 100 insertions, 44 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index f331e2bde88a..1967a7edc10c 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -238,9 +238,11 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
                         goto bailout_interface_put;
                 mutex_unlock(&serial->disc_mutex);
         }
-
         mutex_unlock(&port->mutex);
-        return 0;
+        /* Now do the correct tty layer semantics */
+        retval = tty_port_block_til_ready(&port->port, tty, filp);
+        if (retval == 0)
+                return 0;
 
 bailout_interface_put:
         usb_autopm_put_interface(serial->interface);
@@ -259,64 +261,89 @@ bailout_serial_put:
         return retval;
 }
 
-static void serial_close(struct tty_struct *tty, struct file *filp)
+/**
+ *      serial_do_down          -       shut down hardware
+ *      @port: port to shut down
+ *
+ *      Shut down a USB port unless it is the console. We never shut down the
+ *      console hardware as it will always be in use.
+ *
+ *      Don't free any resources at this point
+ */
+static void serial_do_down(struct usb_serial_port *port)
 {
-        struct usb_serial_port *port = tty->driver_data;
+        struct usb_serial_driver *drv = port->serial->type;
         struct usb_serial *serial;
         struct module *owner;
-        int count;
 
-        if (!port)
+        /* The console is magical, do not hang up the console hardware
+           or there will be tears */
+        if (port->console)
                 return;
 
-        dbg("%s - port %d", __func__, port->number);
-
         mutex_lock(&port->mutex);
         serial = port->serial;
         owner = serial->type->driver.owner;
 
-        if (port->port.count == 0) {
-                mutex_unlock(&port->mutex);
-                return;
-        }
-
-        if (port->port.count == 1)
-                /* only call the device specific close if this
-                 * port is being closed by the last owner. Ensure we do
-                 * this before we drop the port count. The call is protected
-                 * by the port mutex
-                 */
-                serial->type->close(tty, port, filp);
-
-        if (port->port.count == (port->console ? 2 : 1)) {
-                struct tty_struct *tty = tty_port_tty_get(&port->port);
-                if (tty) {
-                        /* We must do this before we drop the port count to
-                           zero. */
-                        if (tty->driver_data)
-                                tty->driver_data = NULL;
-                        tty_port_tty_set(&port->port, NULL);
-                        tty_kref_put(tty);
-                }
-        }
+        if (drv->close)
+                drv->close(port);
 
-        --port->port.count;
-        count = port->port.count;
         mutex_unlock(&port->mutex);
-        put_device(&port->dev);
+}
+
+/**
+ *      serial_do_free          -       free resources post close/hangup
+ *      @port: port to free up
+ *
+ *      Do the resource freeing and refcount dropping for the port. We must
+ *      be careful about ordering and we must avoid freeing up the console.
+ */
 
+static void serial_do_free(struct usb_serial_port *port)
+{
+        struct usb_serial *serial;
+        struct module *owner;
+
+        /* The console is magical, do not hang up the console hardware
+           or there will be tears */
+        if (port->console)
+                return;
+
+        serial = port->serial;
+        owner = serial->type->driver.owner;
+        put_device(&port->dev);
         /* Mustn't dereference port any more */
-        if (count == 0) {
-                mutex_lock(&serial->disc_mutex);
-                if (!serial->disconnected)
-                        usb_autopm_put_interface(serial->interface);
-                mutex_unlock(&serial->disc_mutex);
-        }
+        mutex_lock(&serial->disc_mutex);
+        if (!serial->disconnected)
+                usb_autopm_put_interface(serial->interface);
+        mutex_unlock(&serial->disc_mutex);
         usb_serial_put(serial);
-
         /* Mustn't dereference serial any more */
-        if (count == 0)
-                module_put(owner);
+        module_put(owner);
+}
+
+static void serial_close(struct tty_struct *tty, struct file *filp)
+{
+        struct usb_serial_port *port = tty->driver_data;
+
+        dbg("%s - port %d", __func__, port->number);
+
+
+        if (tty_port_close_start(&port->port, tty, filp) == 0)
+                return;
+
+        serial_do_down(port);           
+        tty_port_close_end(&port->port, tty);
+        tty_port_tty_set(&port->port, NULL);
+        serial_do_free(port);
+}
+
+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);
 }
 
 static int serial_write(struct tty_struct *tty, const unsigned char *buf,
@@ -648,6 +675,29 @@ static struct usb_serial_driver *search_serial_device(
         return NULL;
 }
 
+static int serial_carrier_raised(struct tty_port *port)
+{
+        struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
+        struct usb_serial_driver *drv = p->serial->type;
+        if (drv->carrier_raised)
+                return drv->carrier_raised(p);
+        /* No carrier control - don't block */
+        return 1;       
+}
+
+static void serial_dtr_rts(struct tty_port *port, int on)
+{
+        struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
+        struct usb_serial_driver *drv = p->serial->type;
+        if (drv->dtr_rts)
+                drv->dtr_rts(p, on);
+}
+
+static const struct tty_port_operations serial_port_ops = {
+        .carrier_raised = serial_carrier_raised,
+        .dtr_rts = serial_dtr_rts,
+};
+
 int usb_serial_probe(struct usb_interface *interface,
                                const struct usb_device_id *id)
 {
@@ -841,6 +891,7 @@ int usb_serial_probe(struct usb_interface *interface,
                 if (!port)
                         goto probe_error;
                 tty_port_init(&port->port);
+                port->port.ops = &serial_port_ops;
                 port->serial = serial;
                 spin_lock_init(&port->lock);
                 mutex_init(&port->mutex);
@@ -1071,6 +1122,9 @@ void usb_serial_disconnect(struct usb_interface *interface)
                 if (port) {
                         struct tty_struct *tty = tty_port_tty_get(&port->port);
                         if (tty) {
+                                /* The hangup will occur asynchronously but
+                                   the object refcounts will sort out all the
+                                   cleanup */
                                 tty_hangup(tty);
                                 tty_kref_put(tty);
                         }
@@ -1135,6 +1189,7 @@ static const struct tty_operations serial_ops = {
         .open =                 serial_open,
         .close =                serial_close,
         .write =                serial_write,
+        .hangup =               serial_hangup,
         .write_room =           serial_write_room,
         .ioctl =                serial_ioctl,
         .set_termios =          serial_set_termios,
@@ -1147,6 +1202,7 @@ static const struct tty_operations serial_ops = {
         .proc_fops =            &serial_proc_fops,
 };
 
+
 struct tty_driver *usb_serial_tty_driver;
 
 static int __init usb_serial_init(void)