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Commit 346abf2a authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Greg Kroah-Hartman
Browse files

tty: fix __tty_insert_flip_char regression 



commit 8a5a90a2a477b86a3dc2eaa5a706db9bfdd647ca upstream.

Sergey noticed a small but fatal mistake in __tty_insert_flip_char,
leading to an oops in an interrupt handler when using any serial
port.

The problem is that I accidentally took the tty_buffer pointer
before calling __tty_buffer_request_room(), which replaces the
buffer. This moves the pointer lookup to the right place after
allocating the new buffer space.

Fixes: 979990c62848 ("tty: improve tty_insert_flip_char() fast path")
Reported-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 75046242

drivers/tty/tty_buffer.c

+2 −1
Original line number Diff line number Diff line
@@ -372,12 +372,13 @@ EXPORT_SYMBOL(tty_insert_flip_string_flags); 
 */

int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag)

{

	struct tty_buffer *tb = port->buf.tail;

	struct tty_buffer *tb;

	int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0;



	if (!__tty_buffer_request_room(port, 1, flags))

		return 0;



	tb = port->buf.tail;

	if (~tb->flags & TTYB_NORMAL)

		*flag_buf_ptr(tb, tb->used) = flag;

	*char_buf_ptr(tb, tb->used++) = ch;