tty: The big operations rework
- Operations are now a shared const function block as with most other Linux
objects
- Introduce wrappers for some optional functions to get consistent behaviour
- Wrap put_char which used to be patched by the tty layer
- Document which functions are needed/optional
- Make put_char report success/fail
- Cache the driver->ops pointer in the tty as tty->ops
- Remove various surplus lock calls we no longer need
- Remove proc_write method as noted by Alexey Dobriyan
- Introduce some missing sanity checks where certain driver/ldisc
combinations would oops as they didn't check needed methods were present
[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index a9934a3..0cb0d77 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -296,16 +296,14 @@
struct usb_serial_port *port = tty->driver_data;
int retval = -ENODEV;
- if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
+ if (port->serial->dev->state == USB_STATE_NOTATTACHED)
goto exit;
dbg("%s - port %d, %d byte(s)", __func__, port->number, count);
- if (!port->open_count) {
- retval = -EINVAL;
- dbg("%s - port not opened", __func__);
- goto exit;
- }
+ /* open_count is managed under the mutex lock for the tty so cannot
+ drop to zero until after the last close completes */
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function */
retval = port->serial->type->write(port, buf, count);
@@ -317,61 +315,28 @@
static int serial_write_room (struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
- int retval = -ENODEV;
-
- if (!port)
- goto exit;
-
dbg("%s - port %d", __func__, port->number);
-
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- goto exit;
- }
-
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function */
- retval = port->serial->type->write_room(port);
-
-exit:
- return retval;
+ return port->serial->type->write_room(port);
}
static int serial_chars_in_buffer (struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
- int retval = -ENODEV;
-
- if (!port)
- goto exit;
-
dbg("%s = port %d", __func__, port->number);
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- goto exit;
- }
-
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function */
- retval = port->serial->type->chars_in_buffer(port);
-
-exit:
- return retval;
+ return port->serial->type->chars_in_buffer(port);
}
static void serial_throttle (struct tty_struct * tty)
{
struct usb_serial_port *port = tty->driver_data;
-
- if (!port)
- return;
-
dbg("%s - port %d", __func__, port->number);
- if (!port->open_count) {
- dbg ("%s - port not open", __func__);
- return;
- }
-
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function */
if (port->serial->type->throttle)
port->serial->type->throttle(port);
@@ -380,17 +345,9 @@
static void serial_unthrottle (struct tty_struct * tty)
{
struct usb_serial_port *port = tty->driver_data;
-
- if (!port)
- return;
-
dbg("%s - port %d", __func__, port->number);
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- return;
- }
-
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function */
if (port->serial->type->unthrottle)
port->serial->type->unthrottle(port);
@@ -401,42 +358,27 @@
struct usb_serial_port *port = tty->driver_data;
int retval = -ENODEV;
- lock_kernel();
- if (!port)
- goto exit;
-
dbg("%s - port %d, cmd 0x%.4x", __func__, port->number, cmd);
- /* Caution - port->open_count is BKL protected */
- if (!port->open_count) {
- dbg ("%s - port not open", __func__);
- goto exit;
- }
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function if it is available */
- if (port->serial->type->ioctl)
+ if (port->serial->type->ioctl) {
+ lock_kernel();
retval = port->serial->type->ioctl(port, file, cmd, arg);
+ unlock_kernel();
+ }
else
retval = -ENOIOCTLCMD;
-exit:
- unlock_kernel();
return retval;
}
static void serial_set_termios (struct tty_struct *tty, struct ktermios * old)
{
struct usb_serial_port *port = tty->driver_data;
-
- if (!port)
- return;
-
dbg("%s - port %d", __func__, port->number);
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- return;
- }
-
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function if it is available */
if (port->serial->type->set_termios)
port->serial->type->set_termios(port, old);
@@ -448,24 +390,15 @@
{
struct usb_serial_port *port = tty->driver_data;
- lock_kernel();
- if (!port) {
- unlock_kernel();
- return;
- }
-
dbg("%s - port %d", __func__, port->number);
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- unlock_kernel();
- return;
- }
-
+ WARN_ON(!port->open_count);
/* pass on to the driver specific version of this function if it is available */
- if (port->serial->type->break_ctl)
+ if (port->serial->type->break_ctl) {
+ lock_kernel();
port->serial->type->break_ctl(port, break_state);
- unlock_kernel();
+ unlock_kernel();
+ }
}
static int serial_read_proc (char *page, char **start, off_t off, int count, int *eof, void *data)
@@ -519,19 +452,11 @@
{
struct usb_serial_port *port = tty->driver_data;
- if (!port)
- return -ENODEV;
-
dbg("%s - port %d", __func__, port->number);
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- return -ENODEV;
- }
-
+ WARN_ON(!port->open_count);
if (port->serial->type->tiocmget)
return port->serial->type->tiocmget(port, file);
-
return -EINVAL;
}
@@ -540,19 +465,11 @@
{
struct usb_serial_port *port = tty->driver_data;
- if (!port)
- return -ENODEV;
-
dbg("%s - port %d", __func__, port->number);
- if (!port->open_count) {
- dbg("%s - port not open", __func__);
- return -ENODEV;
- }
-
+ WARN_ON(!port->open_count);
if (port->serial->type->tiocmset)
return port->serial->type->tiocmset(port, file, set, clear);
-
return -EINVAL;
}