Merge tag 'tty-6.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver fixes from Greg KH:
 "Here are some small tty/serial/vt driver fixes for 6.0-rc4 that
  resolve a number of reported issues:

   - n_gsm fixups for previous changes that caused problems

   - much-reported serdev crash fix that showed up in 6.0-rc1

   - vt font selection bugfix

   - kerneldoc build warning fixes

   - other tiny serial core fixes

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

* tag 'tty-6.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: n_gsm: avoid call of sleeping functions from atomic context
  tty: n_gsm: replace kicktimer with delayed_work
  tty: n_gsm: initialize more members at gsm_alloc_mux()
  tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf()
  tty: serial: atmel: Preserve previous USART mode if RS485 disabled
  tty: serial: lpuart: disable flow control while waiting for the transmit engine to complete
  tty: Fix lookahead_buf crash with serdev
  serial: fsl_lpuart: RS485 RTS polariy is inverse
  vt: Clear selection before changing the font
  serial: document start_rx member at struct uart_ops

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 9fdecc795b6b..5e287dedce01 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -470,7 +470,6 @@ static void lookahead_bufs(struct tty_port *port, struct tty_buffer *head)
 
 	while (head) {
 		struct tty_buffer *next;
-		unsigned char *p, *f = NULL;
 		unsigned int count;
 
 		/*
@@ -489,11 +488,16 @@ static void lookahead_bufs(struct tty_port *port, struct tty_buffer *head)
 			continue;
 		}
 
-		p = char_buf_ptr(head, head->lookahead);
-		if (~head->flags & TTYB_NORMAL)
-			f = flag_buf_ptr(head, head->lookahead);
+		if (port->client_ops->lookahead_buf) {
+			unsigned char *p, *f = NULL;
+
+			p = char_buf_ptr(head, head->lookahead);
+			if (~head->flags & TTYB_NORMAL)
+				f = flag_buf_ptr(head, head->lookahead);
+
+			port->client_ops->lookahead_buf(port, p, f, count);
+		}
 
-		port->client_ops->lookahead_buf(port, p, f, count);
 		head->lookahead += count;
 	}
 }