linux-kernel - [PATCH 22/38] vt: make tc write more obvious in vc_con_write

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Date:   Mon, 15 Jun 2020 09:48:54 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 22/38] vt: make tc write more obvious in vc_con_write_normal

Nested ternary operators spread over 4 lines are really evil for
reading. Turn the outer one to proper 'if'. Now, we see, there is a
common path, so the code can be simplified. This way, the code is
understandable now.

Checked using symbolic execution (klee), that the old and new behaviors
are the same.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/tty/vt/vt.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 72ae8ede1ac9..4686f8b9251d 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2787,11 +2787,14 @@ static int vc_con_write_normal(struct vc_data *vc, int tc, int c,
 		if (vc->vc_decim)
 			insert_char(vc, 1);
 		vc_uniscr_putc(vc, next_c);
-		scr_writew(himask ?
-			     ((vc_attr << 8) & ~himask) +
-			     ((tc & 0x100) ? himask : 0) + (tc & 0xff) :
-			     (vc_attr << 8) + tc,
-			   (u16 *)vc->vc_pos);
+
+		if (himask)
+			tc = ((tc & 0x100) ? himask : 0) |
+			      (tc &  0xff);
+		tc |= (vc_attr << 8) & ~himask;
+
+		scr_writew(tc, (u16 *)vc->vc_pos);
+
 		if (con_should_update(vc) && draw->x < 0) {
 			draw->x = vc->state.x;
 			draw->from = vc->vc_pos;
-- 
2.27.0