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tty: tty_port: Change the buffer allocator locking

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We want to be able to do this without regard for the activate/own open
method being used which causes a problem using port->mutex. Add another
mutex for now. Once everything uses port_open to do buffer allocs we can
kill it back off

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox 2009-11-30 13:16:41 +00:00 committed by Greg Kroah-Hartman
parent 1f100b323d
commit 44e4909e45
2 changed files with 6 additions and 4 deletions
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9
drivers/char/tty_port.c
View file

@ -25,6 +25,7 @@ void tty_port_init(struct tty_port *port)
init_waitqueue_head(&port->close_wait);
init_waitqueue_head(&port->delta_msr_wait);
mutex_init(&port->mutex);
mutex_init(&port->buf_mutex);
spin_lock_init(&port->lock);
port->close_delay = (50 * HZ) / 100;
port->closing_wait = (3000 * HZ) / 100;
@ -34,10 +35,10 @@ EXPORT_SYMBOL(tty_port_init);
int tty_port_alloc_xmit_buf(struct tty_port *port)
{
/* We may sleep in get_zeroed_page() */
mutex_lock(&port->mutex);
mutex_lock(&port->buf_mutex);
if (port->xmit_buf == NULL)
port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
mutex_unlock(&port->mutex);
mutex_unlock(&port->buf_mutex);
if (port->xmit_buf == NULL)
return -ENOMEM;
return 0;
@ -46,12 +47,12 @@ EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
void tty_port_free_xmit_buf(struct tty_port *port)
{
mutex_lock(&port->mutex);
mutex_lock(&port->buf_mutex);
if (port->xmit_buf != NULL) {
free_page((unsigned long)port->xmit_buf);
port->xmit_buf = NULL;
}
mutex_unlock(&port->mutex);
mutex_unlock(&port->buf_mutex);
}
EXPORT_SYMBOL(tty_port_free_xmit_buf);

1
include/linux/tty.h
View file

@ -212,6 +212,7 @@ struct tty_port {
wait_queue_head_t delta_msr_wait; /* Modem status change */
unsigned long flags; /* TTY flags ASY_*/
struct mutex mutex; /* Locking */
struct mutex buf_mutex; /* Buffer alloc lock */
unsigned char *xmit_buf; /* Optional buffer */
unsigned int close_delay; /* Close port delay */
unsigned int closing_wait; /* Delay for output */