serial: core: Extract uart_alloc_xmit_buf() and uart_free_xmit_buf()

After conversion to the kfifo, it becomes possible to extract two helper
functions for better maintenance and code deduplication. Do it here.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240409174057.1104262-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 5f88c45fbed32c5c2c0f097f639a7edca21c795a..b9d631037ff6b19ffe0690baaf84ef70073d5b92 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -243,25 +243,12 @@ static void uart_change_line_settings(struct tty_struct *tty, struct uart_state
        uart_port_unlock_irq(uport);
 }
 
-/*
- * Startup the port.  This will be called once per open.  All calls
- * will be serialised by the per-port mutex.
- */
-static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
-                            bool init_hw)
+static int uart_alloc_xmit_buf(struct tty_port *port)
 {
-       struct uart_port *uport = uart_port_check(state);
+       struct uart_state *state = container_of(port, struct uart_state, port);
+       struct uart_port *uport;
        unsigned long flags;
        unsigned long page;
-       int retval = 0;
-
-       if (uport->type == PORT_UNKNOWN)
-               return 1;
-
-       /*
-        * Make sure the device is in D0 state.
-        */
-       uart_change_pm(state, UART_PM_STATE_ON);
 
        /*
         * Initialise and allocate the transmit and temporary
@@ -271,7 +258,7 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
        if (!page)
                return -ENOMEM;
 
-       uart_port_lock(state, flags);
+       uport = uart_port_lock(state, flags);
        if (!state->port.xmit_buf) {
                state->port.xmit_buf = (unsigned char *)page;
                kfifo_init(&state->port.xmit_fifo, state->port.xmit_buf,
@@ -281,11 +268,58 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
                uart_port_unlock(uport, flags);
                /*
                 * Do not free() the page under the port lock, see
-                * uart_shutdown().
+                * uart_free_xmit_buf().
                 */
                free_page(page);
        }
 
+       return 0;
+}
+
+static void uart_free_xmit_buf(struct tty_port *port)
+{
+       struct uart_state *state = container_of(port, struct uart_state, port);
+       struct uart_port *uport;
+       unsigned long flags;
+       char *xmit_buf;
+
+       /*
+        * Do not free() the transmit buffer page under the port lock since
+        * this can create various circular locking scenarios. For instance,
+        * console driver may need to allocate/free a debug object, which
+        * can end up in printk() recursion.
+        */
+       uport = uart_port_lock(state, flags);
+       xmit_buf = port->xmit_buf;
+       port->xmit_buf = NULL;
+       INIT_KFIFO(port->xmit_fifo);
+       uart_port_unlock(uport, flags);
+
+       free_page((unsigned long)xmit_buf);
+}
+
+/*
+ * Startup the port.  This will be called once per open.  All calls
+ * will be serialised by the per-port mutex.
+ */
+static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
+                            bool init_hw)
+{
+       struct uart_port *uport = uart_port_check(state);
+       int retval;
+
+       if (uport->type == PORT_UNKNOWN)
+               return 1;
+
+       /*
+        * Make sure the device is in D0 state.
+        */
+       uart_change_pm(state, UART_PM_STATE_ON);
+
+       retval = uart_alloc_xmit_buf(&state->port);
+       if (retval)
+               return retval;
+
        retval = uport->ops->startup(uport);
        if (retval == 0) {
                if (uart_console(uport) && uport->cons->cflag) {
@@ -347,8 +381,6 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 {
        struct uart_port *uport = uart_port_check(state);
        struct tty_port *port = &state->port;
-       unsigned long flags;
-       char *xmit_buf = NULL;
 
        /*
         * Set the TTY IO error marker
@@ -381,19 +413,7 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
         */
        tty_port_set_suspended(port, false);
 
-       /*
-        * Do not free() the transmit buffer page under the port lock since
-        * this can create various circular locking scenarios. For instance,
-        * console driver may need to allocate/free a debug object, which
-        * can endup in printk() recursion.
-        */
-       uart_port_lock(state, flags);
-       xmit_buf = port->xmit_buf;
-       port->xmit_buf = NULL;
-       INIT_KFIFO(port->xmit_fifo);
-       uart_port_unlock(uport, flags);
-
-       free_page((unsigned long)xmit_buf);
+       uart_free_xmit_buf(port);
 }
 
 /**
@@ -1747,7 +1767,6 @@ static void uart_tty_port_shutdown(struct tty_port *port)
 {
        struct uart_state *state = container_of(port, struct uart_state, port);
        struct uart_port *uport = uart_port_check(state);
-       char *buf;
 
        /*
         * At this point, we stop accepting input.  To do this, we
@@ -1769,16 +1788,7 @@ static void uart_tty_port_shutdown(struct tty_port *port)
         */
        tty_port_set_suspended(port, false);
 
-       /*
-        * Free the transmit buffer.
-        */
-       uart_port_lock_irq(uport);
-       buf = port->xmit_buf;
-       port->xmit_buf = NULL;
-       INIT_KFIFO(port->xmit_fifo);
-       uart_port_unlock_irq(uport);
-
-       free_page((unsigned long)buf);
+       uart_free_xmit_buf(port);
 
        uart_change_pm(state, UART_PM_STATE_OFF);
 }