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tty: usb-serial krefs

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Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.

Contains two err->dev_err changes merged together to fix clashes in the
-next tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox
2008-10-13 10:39:46 +01:00
committed by Linus Torvalds
parent 95f9bfc6b7
commit 4a90f09b20
37 changed files with 313 additions and 208 deletions
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41
drivers/char/tty_port.c
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@@ -23,6 +23,7 @@ void tty_port_init(struct tty_port *port)
init_waitqueue_head(&port->open_wait);
init_waitqueue_head(&port->close_wait);
mutex_init(&port->mutex);
spin_lock_init(&port->lock);
port->close_delay = (50 * HZ) / 100;
port->closing_wait = (3000 * HZ) / 100;
}
@@ -53,3 +54,43 @@ void tty_port_free_xmit_buf(struct tty_port *port)
EXPORT_SYMBOL(tty_port_free_xmit_buf);
/**
* tty_port_tty_get - get a tty reference
* @port: tty port
*
* Return a refcount protected tty instance or NULL if the port is not
* associated with a tty (eg due to close or hangup)
*/
struct tty_struct *tty_port_tty_get(struct tty_port *port)
{
unsigned long flags;
struct tty_struct *tty;
spin_lock_irqsave(&port->lock, flags);
tty = tty_kref_get(port->tty);
spin_unlock_irqrestore(&port->lock, flags);
return tty;
}
EXPORT_SYMBOL(tty_port_tty_get);
/**
* tty_port_tty_set - set the tty of a port
* @port: tty port
* @tty: the tty
*
* Associate the port and tty pair. Manages any internal refcounts.
* Pass NULL to deassociate a port
*/
void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
if (port->tty)
tty_kref_put(port->tty);
port->tty = tty;
spin_unlock_irqrestore(&port->lock, flags);
}
EXPORT_SYMBOL(tty_port_tty_set);