net/irda: Fix port open counts

Saving the port count bump is unsafe. If the tty is hung up while
this open was blocking, the port count is zeroed.

Explicitly check if the tty was hung up while blocking, and correct
the port count if not.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/irda/ircomm/ircomm_tty.c b/net/irda/ircomm/ircomm_tty.c
index 9a5fd3c..1721dc7 100644 (file)
--- a/net/irda/ircomm/ircomm_tty.c
+++ b/net/irda/ircomm/ircomm_tty.c
@@ -280,7 +280,7 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
        struct tty_port *port = &self->port;
        DECLARE_WAITQUEUE(wait, current);
        int             retval;
-       int             do_clocal = 0, extra_count = 0;
+       int             do_clocal = 0;
        unsigned long   flags;
 
        IRDA_DEBUG(2, "%s()\n", __func__ );
@@ -315,10 +315,8 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
              __FILE__, __LINE__, tty->driver->name, port->count);
 
        spin_lock_irqsave(&port->lock, flags);
-       if (!tty_hung_up_p(filp)) {
-               extra_count = 1;
+       if (!tty_hung_up_p(filp))
                port->count--;
-       }
        spin_unlock_irqrestore(&port->lock, flags);
        port->blocked_open++;
 
@@ -361,12 +359,10 @@ static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
        __set_current_state(TASK_RUNNING);
        remove_wait_queue(&port->open_wait, &wait);
 
-       if (extra_count) {
-               /* ++ is not atomic, so this should be protected - Jean II */
-               spin_lock_irqsave(&port->lock, flags);
+       spin_lock_irqsave(&port->lock, flags);
+       if (!tty_hung_up_p(filp))
                port->count++;
-               spin_unlock_irqrestore(&port->lock, flags);
-       }
+       spin_unlock_irqrestore(&port->lock, flags);
        port->blocked_open--;
 
        IRDA_DEBUG(1, "%s(%d):block_til_ready after blocking on %s open_count=%d\n",