TTY/Serial driver fixes for 5.0-rc4

Here are a number of small tty core and serial driver fixes for 5.0-rc4
 to resolve some reported issues.
 
 Nothing major, the small serial driver fixes, a tty core fixup for a
 crash that was reported, and some good vt fixes from Nicolas Pitre as he
 seems to be auditing that chunk of code a lot lately.
 
 All of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver fixes from Greg KH:
 "Here are a number of small tty core and serial driver fixes for
  5.0-rc4 to resolve some reported issues.

  Nothing major, the small serial driver fixes, a tty core fixup for a
  crash that was reported, and some good vt fixes from Nicolas Pitre as
  he seems to be auditing that chunk of code a lot lately.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: fsl_lpuart: fix maximum acceptable baud rate with over-sampling
  tty: serial: qcom_geni_serial: Allow mctrl when flow control is disabled
  tty: Handle problem if line discipline does not have receive_buf
  vgacon: unconfuse vc_origin when using soft scrollback
  vt: invoke notifier on screen size change
  vt: always call notifier with the console lock held
  vt: make vt_console_print() compatible with the unicode screen buffer
  tty/n_hdlc: fix __might_sleep warning
  serial: 8250: Fix serial8250 initialization crash
  uart: Fix crash in uart_write and uart_put_char

drivers/tty/n_hdlc.c

@@ -597,6 +597,7 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
 				/* too large for caller's buffer */
 				ret = -EOVERFLOW;
 			} else {
+				__set_current_state(TASK_RUNNING);
 				if (copy_to_user(buf, rbuf->buf, rbuf->count))
 					ret = -EFAULT;
 				else

drivers/tty/serial/8250/8250_core.c

@@ -1070,15 +1070,16 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 
 			ret = 0;
 		}
-	}
 
-	/* Initialise interrupt backoff work if required */
-	if (up->overrun_backoff_time_ms > 0) {
-		uart->overrun_backoff_time_ms = up->overrun_backoff_time_ms;
-		INIT_DELAYED_WORK(&uart->overrun_backoff,
-				  serial_8250_overrun_backoff_work);
-	} else {
-		uart->overrun_backoff_time_ms = 0;
+		/* Initialise interrupt backoff work if required */
+		if (up->overrun_backoff_time_ms > 0) {
+			uart->overrun_backoff_time_ms =
+				up->overrun_backoff_time_ms;
+			INIT_DELAYED_WORK(&uart->overrun_backoff,
+					serial_8250_overrun_backoff_work);
+		} else {
+			uart->overrun_backoff_time_ms = 0;
+		}
 	}
 
 	mutex_unlock(&serial_mutex);

drivers/tty/serial/fsl_lpuart.c

@@ -1697,7 +1697,7 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	}
 
 	/* ask the core to calculate the divisor */
-	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
+	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 4);
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 

drivers/tty/serial/qcom_geni_serial.c

@@ -225,7 +225,7 @@ static unsigned int qcom_geni_serial_get_mctrl(struct uart_port *uport)
 	unsigned int mctrl = TIOCM_DSR | TIOCM_CAR;
 	u32 geni_ios;
 
-	if (uart_console(uport) || !uart_cts_enabled(uport)) {
+	if (uart_console(uport)) {
 		mctrl |= TIOCM_CTS;
 	} else {
 		geni_ios = readl_relaxed(uport->membase + SE_GENI_IOS);
@@ -241,7 +241,7 @@ static void qcom_geni_serial_set_mctrl(struct uart_port *uport,
 {
 	u32 uart_manual_rfr = 0;
 
-	if (uart_console(uport) || !uart_cts_enabled(uport))
+	if (uart_console(uport))
 		return;
 
 	if (!(mctrl & TIOCM_RTS))

drivers/tty/serial/serial_core.c

@@ -550,10 +550,12 @@ static int uart_put_char(struct tty_struct *tty, unsigned char c)
 	int ret = 0;
 
 	circ = &state->xmit;
-	if (!circ->buf)
-		return 0;
-
 	port = uart_port_lock(state, flags);
+	if (!circ->buf) {
+		uart_port_unlock(port, flags);
+		return 0;
+	}
+
 	if (port && uart_circ_chars_free(circ) != 0) {
 		circ->buf[circ->head] = c;
 		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
@@ -586,11 +588,13 @@ static int uart_write(struct tty_struct *tty,
 		return -EL3HLT;
 	}
 
-	circ = &state->xmit;
-	if (!circ->buf)
-		return 0;
-
 	port = uart_port_lock(state, flags);
+	circ = &state->xmit;
+	if (!circ->buf) {
+		uart_port_unlock(port, flags);
+		return 0;
+	}
+
 	while (port) {
 		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
 		if (count < c)

drivers/tty/tty_io.c

@@ -2189,7 +2189,8 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
 	ld = tty_ldisc_ref_wait(tty);
 	if (!ld)
 		return -EIO;
-	ld->ops->receive_buf(tty, &ch, &mbz, 1);
+	if (ld->ops->receive_buf)
+		ld->ops->receive_buf(tty, &ch, &mbz, 1);
 	tty_ldisc_deref(ld);
 	return 0;
 }

drivers/tty/vt/vt.c

@@ -1272,6 +1272,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	if (con_is_visible(vc))
 		update_screen(vc);
 	vt_event_post(VT_EVENT_RESIZE, vc->vc_num, vc->vc_num);
+	notify_update(vc);
 	return err;
 }
 
@@ -2764,8 +2765,8 @@ rescan_last_byte:
 	con_flush(vc, draw_from, draw_to, &draw_x);
 	vc_uniscr_debug_check(vc);
 	console_conditional_schedule();
-	console_unlock();
 	notify_update(vc);
+	console_unlock();
 	return n;
 }
 
@@ -2884,8 +2885,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
 	unsigned char c;
 	static DEFINE_SPINLOCK(printing_lock);
 	const ushort *start;
-	ushort cnt = 0;
-	ushort myx;
+	ushort start_x, cnt;
 	int kmsg_console;
 
 	/* console busy or not yet initialized */
@@ -2898,10 +2898,6 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
 	if (kmsg_console && vc_cons_allocated(kmsg_console - 1))
 		vc = vc_cons[kmsg_console - 1].d;
 
-	/* read `x' only after setting currcons properly (otherwise
-	   the `x' macro will read the x of the foreground console). */
-	myx = vc->vc_x;
-
 	if (!vc_cons_allocated(fg_console)) {
 		/* impossible */
 		/* printk("vt_console_print: tty %d not allocated ??\n", currcons+1); */
@@ -2916,53 +2912,41 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
 		hide_cursor(vc);
 
 	start = (ushort *)vc->vc_pos;
-
-	/* Contrived structure to try to emulate original need_wrap behaviour
-	 * Problems caused when we have need_wrap set on '\n' character */
+	start_x = vc->vc_x;
+	cnt = 0;
 	while (count--) {
 		c = *b++;
 		if (c == 10 || c == 13 || c == 8 || vc->vc_need_wrap) {
-			if (cnt > 0) {
-				if (con_is_visible(vc))
-					vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
-				vc->vc_x += cnt;
-				if (vc->vc_need_wrap)
-					vc->vc_x--;
-				cnt = 0;
-			}
+			if (cnt && con_is_visible(vc))
+				vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, start_x);
+			cnt = 0;
 			if (c == 8) {		/* backspace */
 				bs(vc);
 				start = (ushort *)vc->vc_pos;
-				myx = vc->vc_x;
+				start_x = vc->vc_x;
 				continue;
 			}
 			if (c != 13)
 				lf(vc);
 			cr(vc);
 			start = (ushort *)vc->vc_pos;
-			myx = vc->vc_x;
+			start_x = vc->vc_x;
 			if (c == 10 || c == 13)
 				continue;
 		}
+		vc_uniscr_putc(vc, c);
 		scr_writew((vc->vc_attr << 8) + c, (unsigned short *)vc->vc_pos);
 		notify_write(vc, c);
 		cnt++;
-		if (myx == vc->vc_cols - 1) {
-			vc->vc_need_wrap = 1;
-			continue;
-		}
-		vc->vc_pos += 2;
-		myx++;
-	}
-	if (cnt > 0) {
-		if (con_is_visible(vc))
-			vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
-		vc->vc_x += cnt;
-		if (vc->vc_x == vc->vc_cols) {
-			vc->vc_x--;
+		if (vc->vc_x == vc->vc_cols - 1) {
 			vc->vc_need_wrap = 1;
+		} else {
+			vc->vc_pos += 2;
+			vc->vc_x++;
 		}
 	}
+	if (cnt && con_is_visible(vc))
+		vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, start_x);
 	set_cursor(vc);
 	notify_update(vc);
 

drivers/video/console/vgacon.c

@@ -271,6 +271,7 @@ static void vgacon_scrollback_update(struct vc_data *c, int t, int count)
 
 static void vgacon_restore_screen(struct vc_data *c)
 {
+	c->vc_origin = c->vc_visible_origin;
 	vgacon_scrollback_cur->save = 0;
 
 	if (!vga_is_gfx && !vgacon_scrollback_cur->restore) {
@@ -287,8 +288,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
 	int start, end, count, soff;
 
 	if (!lines) {
-		c->vc_visible_origin = c->vc_origin;
-		vga_set_mem_top(c);
+		vgacon_restore_screen(c);
 		return;
 	}
 
@@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
 	if (!vgacon_scrollback_cur->save) {
 		vgacon_cursor(c, CM_ERASE);
 		vgacon_save_screen(c);
+		c->vc_origin = (unsigned long)c->vc_screenbuf;
 		vgacon_scrollback_cur->save = 1;
 	}
 
@@ -335,7 +336,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
 		int copysize;
 
 		int diff = c->vc_rows - count;
-		void *d = (void *) c->vc_origin;
+		void *d = (void *) c->vc_visible_origin;
 		void *s = (void *) c->vc_screenbuf;
 
 		count *= c->vc_size_row;