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Subject[088/136] tty: Add a full port_close function
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Alan Cox <alan@linux.intel.com>
commit 7ca0ff9ab3218ec443a7a9ad247e4650373ed41e upstream.

Now we are extracting out methods for shutdown and the like we can add a
proper tty_port_close method that knows all the innards of the tty closing
process and hides the lot from the caller.

At some point in the future this will be paired with a similar open()
helper and the drivers can stick to hardware management.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/char/tty_port.c | 29 +++++++++++++++++++++++++++--
include/linux/tty.h | 8 +++++++-
2 files changed, 34 insertions(+), 3 deletions(-)
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -96,6 +96,14 @@ void tty_port_tty_set(struct tty_port *p
}
EXPORT_SYMBOL(tty_port_tty_set);

+static void tty_port_shutdown(struct tty_port *port)
+{
+ if (port->ops->shutdown &&
+ test_and_clear_bit(ASYNC_INITIALIZED, &port->flags))
+ port->ops->shutdown(port);
+
+}
+
/**
* tty_port_hangup - hangup helper
* @port: tty port
@@ -116,6 +124,7 @@ void tty_port_hangup(struct tty_port *po
port->tty = NULL;
spin_unlock_irqrestore(&port->lock, flags);
wake_up_interruptible(&port->open_wait);
+ tty_port_shutdown(port);
}
EXPORT_SYMBOL(tty_port_hangup);

@@ -296,15 +305,17 @@ int tty_port_close_start(struct tty_port

if (port->count) {
spin_unlock_irqrestore(&port->lock, flags);
+ if (port->ops->drop)
+ port->ops->drop(port);
return 0;
}
- port->flags |= ASYNC_CLOSING;
+ set_bit(ASYNC_CLOSING, &port->flags);
tty->closing = 1;
spin_unlock_irqrestore(&port->lock, flags);
/* Don't block on a stalled port, just pull the chain */
if (tty->flow_stopped)
tty_driver_flush_buffer(tty);
- if (port->flags & ASYNC_INITIALIZED &&
+ if (test_bit(ASYNCB_INITIALIZED, &port->flags) &&
port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
tty_wait_until_sent(tty, port->closing_wait);
if (port->drain_delay) {
@@ -318,6 +329,9 @@ int tty_port_close_start(struct tty_port
timeout = 2 * HZ;
schedule_timeout_interruptible(timeout);
}
+ /* Don't call port->drop for the last reference. Callers will want
+ to drop the last active reference in ->shutdown() or the tty
+ shutdown path */
return 1;
}
EXPORT_SYMBOL(tty_port_close_start);
@@ -348,3 +362,14 @@ void tty_port_close_end(struct tty_port
spin_unlock_irqrestore(&port->lock, flags);
}
EXPORT_SYMBOL(tty_port_close_end);
+
+void tty_port_close(struct tty_port *port, struct tty_struct *tty,
+ struct file *filp)
+{
+ if (tty_port_close_start(port, tty, filp) == 0)
+ return;
+ tty_port_shutdown(port);
+ tty_port_close_end(port, tty);
+ tty_port_tty_set(port, NULL);
+}
+EXPORT_SYMBOL(tty_port_close);
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -185,7 +185,12 @@ struct tty_port;
struct tty_port_operations {
/* Return 1 if the carrier is raised */
int (*carrier_raised)(struct tty_port *port);
+ /* Control the DTR line */
void (*dtr_rts)(struct tty_port *port, int raise);
+ /* Called when the last close completes or a hangup finishes
+ IFF the port was initialized. Do not use to free resources */
+ void (*shutdown)(struct tty_port *port);
+ void (*drop)(struct tty_port *port);
};

struct tty_port {
@@ -457,7 +462,8 @@ extern int tty_port_block_til_ready(stru
extern int tty_port_close_start(struct tty_port *port,
struct tty_struct *tty, struct file *filp);
extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
-
+extern void tty_port_close(struct tty_port *port,
+ struct tty_struct *tty, struct file *filp);
extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc);
extern int tty_unregister_ldisc(int disc);
extern int tty_set_ldisc(struct tty_struct *tty, int ldisc);



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