Merge tag 'v4.9.169' into linux-linaro-lsk-v4.9linux-linaro-lsk-v4.9

This is the 4.9.169 stable release

5 files changed, 106 insertions, 12 deletions

diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index 95103054c0e4..fdd2860cb9bd 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -455,4 +455,27 @@ config MIPS_EJTAG_FDC_KGDB_CHAN
 	help
 	  FDC channel number to use for KGDB.
 
+config LDISC_AUTOLOAD
+	bool "Automatically load TTY Line Disciplines"
+	default y
+	help
+	  Historically the kernel has always automatically loaded any
+	  line discipline that is in a kernel module when a user asks
+	  for it to be loaded with the TIOCSETD ioctl, or through other
+	  means.  This is not always the best thing to do on systems
+	  where you know you will not be using some of the more
+	  "ancient" line disciplines, so prevent the kernel from doing
+	  this unless the request is coming from a process with the
+	  CAP_SYS_MODULE permissions.
+
+	  Say 'Y' here if you trust your userspace users to do the right
+	  thing, or if you have only provided the line disciplines that
+	  you know you will be using, or if you wish to continue to use
+	  the traditional method of on-demand loading of these modules
+	  by any user.
+
+	  This functionality can be changed at runtime with the
+	  dev.tty.ldisc_autoload sysctl, this configuration option will
+	  only set the default value of this functionality.
+
 endif # TTY
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index d8e1945cb627..ef688aadb032 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -175,6 +175,8 @@ struct atmel_uart_port {
 	unsigned int		pending_status;
 	spinlock_t		lock_suspended;
 
+	bool			hd_start_rx;	/* can start RX during half-duplex operation */
+
 	int (*prepare_rx)(struct uart_port *port);
 	int (*prepare_tx)(struct uart_port *port);
 	void (*schedule_rx)(struct uart_port *port);
@@ -241,6 +243,12 @@ static inline void atmel_uart_write_char(struct uart_port *port, u8 value)
 
 #endif
 
+static inline int atmel_uart_is_half_duplex(struct uart_port *port)
+{
+	return (port->rs485.flags & SER_RS485_ENABLED) &&
+		!(port->rs485.flags & SER_RS485_RX_DURING_TX);
+}
+
 #ifdef CONFIG_SERIAL_ATMEL_PDC
 static bool atmel_use_pdc_rx(struct uart_port *port)
 {
@@ -492,9 +500,9 @@ static void atmel_stop_tx(struct uart_port *port)
 	/* Disable interrupts */
 	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
 
-	if ((port->rs485.flags & SER_RS485_ENABLED) &&
-	    !(port->rs485.flags & SER_RS485_RX_DURING_TX))
+	if (atmel_uart_is_half_duplex(port))
 		atmel_start_rx(port);
+
 }
 
 /*
@@ -511,8 +519,7 @@ static void atmel_start_tx(struct uart_port *port)
 		return;
 
 	if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
-		if ((port->rs485.flags & SER_RS485_ENABLED) &&
-		    !(port->rs485.flags & SER_RS485_RX_DURING_TX))
+		if (atmel_uart_is_half_duplex(port))
 			atmel_stop_rx(port);
 
 	if (atmel_use_pdc_tx(port))
@@ -809,10 +816,14 @@ static void atmel_complete_tx_dma(void *arg)
 	 */
 	if (!uart_circ_empty(xmit))
 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
-	else if ((port->rs485.flags & SER_RS485_ENABLED) &&
-		 !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
-		/* DMA done, stop TX, start RX for RS485 */
-		atmel_start_rx(port);
+	else if (atmel_uart_is_half_duplex(port)) {
+		/*
+		 * DMA done, re-enable TXEMPTY and signal that we can stop
+		 * TX and start RX for RS485
+		 */
+		atmel_port->hd_start_rx = true;
+		atmel_uart_writel(port, ATMEL_US_IER,
+				  atmel_port->tx_done_mask);
 	}
 
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -1257,9 +1268,20 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 	if (pending & atmel_port->tx_done_mask) {
-		/* Either PDC or interrupt transmission */
 		atmel_uart_writel(port, ATMEL_US_IDR,
 				  atmel_port->tx_done_mask);
+
+		/* Start RX if flag was set and FIFO is empty */
+		if (atmel_port->hd_start_rx) {
+			if (!(atmel_uart_readl(port, ATMEL_US_CSR)
+					& ATMEL_US_TXEMPTY))
+				dev_warn(port->dev, "Should start RX, but TX fifo is not empty\n");
+
+			atmel_port->hd_start_rx = false;
+			atmel_start_rx(port);
+			return;
+		}
+
 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
 	}
 }
@@ -1386,8 +1408,7 @@ static void atmel_tx_pdc(struct uart_port *port)
 		atmel_uart_writel(port, ATMEL_US_IER,
 				  atmel_port->tx_done_mask);
 	} else {
-		if ((port->rs485.flags & SER_RS485_ENABLED) &&
-		    !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
+		if (atmel_uart_is_half_duplex(port)) {
 			/* DMA done, stop TX, start RX for RS485 */
 			atmel_start_rx(port);
 		}
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 41b9a7ccce08..ca9c82ee6c35 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -25,7 +25,7 @@
  * Byte threshold to limit memory consumption for flip buffers.
  * The actual memory limit is > 2x this amount.
  */
-#define TTYB_DEFAULT_MEM_LIMIT	65536
+#define TTYB_DEFAULT_MEM_LIMIT	(640 * 1024UL)
 
 /*
  * We default to dicing tty buffer allocations to this many characters
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 19fe1e8fc124..15e0116e1232 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -520,6 +520,8 @@ void proc_clear_tty(struct task_struct *p)
 	tty_kref_put(tty);
 }
 
+extern void tty_sysctl_init(void);
+
 /**
  * proc_set_tty -  set the controlling terminal
  *
@@ -3705,6 +3707,7 @@ void console_sysfs_notify(void)
  */
 int __init tty_init(void)
 {
+	tty_sysctl_init();
 	cdev_init(&tty_cdev, &tty_fops);
 	if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
 	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 4ab518d43758..3eb3f2a03bbb 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -155,6 +155,13 @@ static void put_ldops(struct tty_ldisc_ops *ldops)
  *		takes tty_ldiscs_lock to guard against ldisc races
  */
 
+#if defined(CONFIG_LDISC_AUTOLOAD)
+	#define INITIAL_AUTOLOAD_STATE	1
+#else
+	#define INITIAL_AUTOLOAD_STATE	0
+#endif
+static int tty_ldisc_autoload = INITIAL_AUTOLOAD_STATE;
+
 static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
 {
 	struct tty_ldisc *ld;
@@ -169,6 +176,8 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
 	 */
 	ldops = get_ldops(disc);
 	if (IS_ERR(ldops)) {
+		if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload)
+			return ERR_PTR(-EPERM);
 		request_module("tty-ldisc-%d", disc);
 		ldops = get_ldops(disc);
 		if (IS_ERR(ldops))
@@ -774,3 +783,41 @@ void tty_ldisc_deinit(struct tty_struct *tty)
 		tty_ldisc_put(tty->ldisc);
 	tty->ldisc = NULL;
 }
+
+static int zero;
+static int one = 1;
+static struct ctl_table tty_table[] = {
+	{
+		.procname	= "ldisc_autoload",
+		.data		= &tty_ldisc_autoload,
+		.maxlen		= sizeof(tty_ldisc_autoload),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+		.extra1		= &zero,
+		.extra2		= &one,
+	},
+	{ }
+};
+
+static struct ctl_table tty_dir_table[] = {
+	{
+		.procname	= "tty",
+		.mode		= 0555,
+		.child		= tty_table,
+	},
+	{ }
+};
+
+static struct ctl_table tty_root_table[] = {
+	{
+		.procname	= "dev",
+		.mode		= 0555,
+		.child		= tty_dir_table,
+	},
+	{ }
+};
+
+void tty_sysctl_init(void)
+{
+	register_sysctl_table(tty_root_table);
+}