Merge branch 'android-4.14-p' into android-exynos-4.14-ww-9610-minor_up-dev

[GitHub/LineageOS/android_kernel_motorola_exynos9610.git] / drivers / tty / serial / serial_core.c

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 3a14cccbd7fffd6428d0a833afabe3045d017d09..574ac2f2f18c27d0cf8777a3e0f70471df7eab09 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -133,6 +133,9 @@ static void __uart_start(struct tty_struct *tty)
        struct uart_state *state = tty->driver_data;
        struct uart_port *port = state->uart_port;
 
+       if (port && port->ops->wake_peer)
+               port->ops->wake_peer(port);
+
        if (port && !uart_tx_stopped(port))
                port->ops->start_tx(port);
 }
@@ -143,6 +146,9 @@ static void uart_start(struct tty_struct *tty)
        struct uart_port *port;
        unsigned long flags;
 
+       if (!state)
+               return;
+
        port = uart_port_lock(state, flags);
        __uart_start(tty);
        uart_port_unlock(port, flags);
@@ -195,6 +201,7 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
 {
        struct uart_port *uport = uart_port_check(state);
        unsigned long page;
+       unsigned long flags = 0;
        int retval = 0;
 
        if (uport->type == PORT_UNKNOWN)
@@ -209,14 +216,22 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
         * Initialise and allocate the transmit and temporary
         * buffer.
         */
-       if (!state->xmit.buf) {
-               /* This is protected by the per port mutex */
-               page = get_zeroed_page(GFP_KERNEL);
-               if (!page)
-                       return -ENOMEM;
+       page = get_zeroed_page(GFP_KERNEL);
+       if (!page)
+               return -ENOMEM;
 
+       uart_port_lock(state, flags);
+       if (!state->xmit.buf) {
                state->xmit.buf = (unsigned char *) page;
                uart_circ_clear(&state->xmit);
+               uart_port_unlock(uport, flags);
+       } else {
+               uart_port_unlock(uport, flags);
+               /*
+                * Do not free() the page under the port lock, see
+                * uart_shutdown().
+                */
+               free_page(page);
        }
 
        retval = uport->ops->startup(uport);
@@ -276,6 +291,8 @@ 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 = 0;
+       char *xmit_buf = NULL;
 
        /*
         * Set the TTY IO error marker
@@ -306,12 +323,18 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
        tty_port_set_suspended(port, 0);
 
        /*
-        * Free the transmit buffer page.
+        * 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.
         */
-       if (state->xmit.buf) {
-               free_page((unsigned long)state->xmit.buf);
-               state->xmit.buf = NULL;
-       }
+       uart_port_lock(state, flags);
+       xmit_buf = state->xmit.buf;
+       state->xmit.buf = NULL;
+       uart_port_unlock(uport, flags);
+
+       if (xmit_buf)
+               free_page((unsigned long)xmit_buf);
 }
 
 /**
@@ -546,10 +569,12 @@ static int uart_put_char(struct tty_struct *tty, unsigned char c)
        int ret = 0;
 
        circ = &state->xmit;
-       if (!circ->buf)
+       port = uart_port_lock(state, flags);
+       if (!circ->buf) {
+               uart_port_unlock(port, flags);
                return 0;
+       }
 
-       port = uart_port_lock(state, flags);
        if (port && uart_circ_chars_free(circ) != 0) {
                circ->buf[circ->head] = c;
                circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
@@ -582,11 +607,13 @@ static int uart_write(struct tty_struct *tty,
                return -EL3HLT;
        }
 
+       port = uart_port_lock(state, flags);
        circ = &state->xmit;
-       if (!circ->buf)
+       if (!circ->buf) {
+               uart_port_unlock(port, flags);
                return 0;
+       }
 
-       port = uart_port_lock(state, flags);
        while (port) {
                c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
                if (count < c)
@@ -987,6 +1014,8 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
                }
        } else {
                retval = uart_startup(tty, state, 1);
+               if (retval == 0)
+                       tty_port_set_initialized(port, true);
                if (retval > 0)
                        retval = 0;
        }
@@ -1155,6 +1184,8 @@ static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
                uport->ops->config_port(uport, flags);
 
                ret = uart_startup(tty, state, 1);
+               if (ret == 0)
+                       tty_port_set_initialized(port, true);
                if (ret > 0)
                        ret = 0;
        }
@@ -2390,6 +2421,9 @@ static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
        struct uart_state *state = drv->state + line;
        struct uart_port *port;
 
+       if (!state)
+               return;
+
        port = uart_port_ref(state);
        if (!port)
                return;