mxser: use tty_port xmit_buf helpers

For the mxser driver to use kfifo, use tty_port_alloc_xmit_buf() and
tty_port_free_xmit_buf() helpers in activate/shutdown, respectively.

As these calls have to be done in a non-atomic context, we have to move
them outside spinlock and make sure irq is really stopped after we write
to the ISR register.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220124071430.14907-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index fbb796f..4ddc12a 100644 (file)
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -742,13 +742,12 @@ static void mxser_disable_and_clear_FIFO(struct mxser_port *info)
 static int mxser_activate(struct tty_port *port, struct tty_struct *tty)
 {
        struct mxser_port *info = container_of(port, struct mxser_port, port);
-       unsigned long page;
        unsigned long flags;
        int ret;
 
-       page = __get_free_page(GFP_KERNEL);
-       if (!page)
-               return -ENOMEM;
+       ret = tty_port_alloc_xmit_buf(port);
+       if (ret < 0)
+               return ret;
 
        spin_lock_irqsave(&info->slock, flags);
 
@@ -758,7 +757,6 @@ static int mxser_activate(struct tty_port *port, struct tty_struct *tty)
                ret = 0;
                goto err_free_xmit;
        }
-       info->port.xmit_buf = (unsigned char *) page;
 
        /*
         * Clear the FIFO buffers and disable them
@@ -825,8 +823,7 @@ static int mxser_activate(struct tty_port *port, struct tty_struct *tty)
 
        return 0;
 err_free_xmit:
-       free_page(page);
-       info->port.xmit_buf = NULL;
+       tty_port_free_xmit_buf(port);
        return ret;
 }
 
@@ -862,14 +859,6 @@ static void mxser_shutdown_port(struct tty_port *port)
         */
        wake_up_interruptible(&info->port.delta_msr_wait);
 
-       /*
-        * Free the xmit buffer, if necessary
-        */
-       if (info->port.xmit_buf) {
-               free_page((unsigned long) info->port.xmit_buf);
-               info->port.xmit_buf = NULL;
-       }
-
        info->IER = 0;
        outb(0x00, info->ioaddr + UART_IER);
 
@@ -884,6 +873,11 @@ static void mxser_shutdown_port(struct tty_port *port)
                mxser_must_no_sw_flow_control(info->ioaddr);
 
        spin_unlock_irqrestore(&info->slock, flags);
+
+       /* make sure ISR is not running while we free the buffer */
+       synchronize_irq(info->board->irq);
+
+       tty_port_free_xmit_buf(port);
 }
 
 /*