From 7e26c84d02d17e7412e6f2471916fd415654a1ba Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Thu, 9 Mar 2023 10:20:32 +0200 Subject: [PATCH] n_tty: Use DIV_ROUND_UP() in room calculation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When PARMRK is set, a character can result in up to 3 chars in the read buffer. Receive code calculates for how many characters there (at least) is room. Convert an opencoded rounding in the calculation to use DIV_ROUND_UP(). Note: the room variable is decremented afterwards by one which ensures the characters will fit into the buffer for real so the code is okay despite rounding upwards. Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230309082035.14880-6-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 2cf263de1366..6d754fc35dce 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include #include @@ -1692,7 +1693,7 @@ n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp, room = N_TTY_BUF_SIZE - (ldata->read_head - tail); if (I_PARMRK(tty)) - room = (room + 2) / 3; + room = DIV_ROUND_UP(room, 3); room--; if (room <= 0) { overflow = ldata->icanon && ldata->canon_head == tail;