TTY/Serial fixes for 4.4-rc6

Here are some tty/serial driver fixes for 4.4-rc6 that resolve some
 reported problems.  All of these have been in linux-next.  The details
 are in the shortlog.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some tty/serial driver fixes for 4.4-rc6 that resolve some
  reported problems.  All of these have been in linux-next.  The details
  are in the shortlog"

* tag 'tty-4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: Fix GPF in flush_to_ldisc()
  serial: earlycon: Add missing spinlock initialization
  serial: sh-sci: Fix length of scatterlist
  n_tty: Fix poll() after buffer-limited eof push read
  serial: 8250_uniphier: fix dl_read and dl_write functions

drivers/tty/n_tty.c

@@ -2054,13 +2054,13 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	size_t eol;
 	size_t tail;
 	int ret, found = 0;
-	bool eof_push = 0;
 
 	/* N.B. avoid overrun if nr == 0 */
-	n = min(*nr, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
-	if (!n)
+	if (!*nr)
 		return 0;
 
+	n = min(*nr + 1, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
+
 	tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
 	size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
 
@@ -2081,12 +2081,11 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	n = eol - tail;
 	if (n > N_TTY_BUF_SIZE)
 		n += N_TTY_BUF_SIZE;
-	n += found;
-	c = n;
+	c = n + found;
 
-	if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
-		n--;
-		eof_push = !n && ldata->read_tail != ldata->line_start;
+	if (!found || read_buf(ldata, eol) != __DISABLED_CHAR) {
+		c = min(*nr, c);
+		n = c;
 	}
 
 	n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
@@ -2116,7 +2115,7 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 			ldata->push = 0;
 		tty_audit_push(tty);
 	}
-	return eof_push ? -EAGAIN : 0;
+	return 0;
 }
 
 extern ssize_t redirected_tty_write(struct file *, const char __user *,
@@ -2273,10 +2272,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 
 		if (ldata->icanon && !L_EXTPROC(tty)) {
 			retval = canon_copy_from_read_buf(tty, &b, &nr);
-			if (retval == -EAGAIN) {
-				retval = 0;
-				continue;
-			} else if (retval)
+			if (retval)
 				break;
 		} else {
 			int uncopied;

drivers/tty/serial/8250/8250_uniphier.c

@@ -115,12 +115,16 @@ static void uniphier_serial_out(struct uart_port *p, int offset, int value)
  */
 static int uniphier_serial_dl_read(struct uart_8250_port *up)
 {
-	return readl(up->port.membase + UNIPHIER_UART_DLR);
+	int offset = UNIPHIER_UART_DLR << up->port.regshift;
+
+	return readl(up->port.membase + offset);
 }
 
 static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
 {
-	writel(value, up->port.membase + UNIPHIER_UART_DLR);
+	int offset = UNIPHIER_UART_DLR << up->port.regshift;
+
+	writel(value, up->port.membase + offset);
 }
 
 static int uniphier_of_serial_setup(struct device *dev, struct uart_port *port,

drivers/tty/serial/earlycon.c

@@ -115,6 +115,7 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
 	if (buf && !parse_options(&early_console_dev, buf))
 		buf = NULL;
 
+	spin_lock_init(&port->lock);
 	port->uartclk = BASE_BAUD * 16;
 	if (port->mapbase)
 		port->membase = earlycon_map(port->mapbase, 64);
@@ -202,6 +203,7 @@ int __init of_setup_earlycon(unsigned long addr,
 	int err;
 	struct uart_port *port = &early_console_dev.port;
 
+	spin_lock_init(&port->lock);
 	port->iotype = UPIO_MEM;
 	port->mapbase = addr;
 	port->uartclk = BASE_BAUD * 16;

drivers/tty/serial/sh-sci.c

@@ -1437,7 +1437,7 @@ static void sci_request_dma(struct uart_port *port)
 			sg_init_table(sg, 1);
 			s->rx_buf[i] = buf;
 			sg_dma_address(sg) = dma;
-			sg->length = s->buf_len_rx;
+			sg_dma_len(sg) = s->buf_len_rx;
 
 			buf += s->buf_len_rx;
 			dma += s->buf_len_rx;

drivers/tty/tty_buffer.c

@@ -450,7 +450,7 @@ receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
 		count = disc->ops->receive_buf2(tty, p, f, count);
 	else {
 		count = min_t(int, count, tty->receive_room);
-		if (count)
+		if (count && disc->ops->receive_buf)
 			disc->ops->receive_buf(tty, p, f, count);
 	}
 	return count;