Prevent an O_NDELAY writer from blocking when a tty write is blocked by the tty atomi...

[safe/jmp/linux-2.6] / drivers / char / n_hdlc.c

diff --git a/drivers/char/n_hdlc.c b/drivers/char/n_hdlc.c
index 337a87f..37f7d34 100644 (file)
--- a/drivers/char/n_hdlc.c
+++ b/drivers/char/n_hdlc.c
@@ -780,13 +780,14 @@ static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
                poll_wait(filp, &tty->write_wait, wait);
 
                /* set bits for operations that won't block */
-               if(n_hdlc->rx_buf_list.head)
+               if (n_hdlc->rx_buf_list.head)
                        mask |= POLLIN | POLLRDNORM;    /* readable */
                if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
                        mask |= POLLHUP;
-               if(tty_hung_up_p(filp))
+               if (tty_hung_up_p(filp))
                        mask |= POLLHUP;
-               if(n_hdlc->tx_free_buf_list.head)
+               if (!tty_is_writelocked(tty) &&
+                               n_hdlc->tx_free_buf_list.head)
                        mask |= POLLOUT | POLLWRNORM;   /* writable */
        }
        return mask;
@@ -861,7 +862,7 @@ static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
        spin_lock_irqsave(&list->spinlock,flags);
        
        buf->link=NULL;
-       if(list->tail)
+       if (list->tail)
                list->tail->link = buf;
        else
                list->head = buf;