[PATCH 2/2] drivers: tty: vt: vt.c: fixed segmentation fault in vt.c

[dimadrumspro@gmail.com]

From: dimaaac <dimadrumspro@gmail.com>

The previous code lacked proper synchronization, leading to potential data corruption and crashes. Added a spin lock to protect shared variable 'scrollback_delta' to prevent concurrent access.

Signed-off-by: dimaaac <dimaac@bk.ru>
---
 drivers/tty/vt/vt.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 5c47f77804f0..29cf7fe11662 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -301,12 +301,13 @@ static inline unsigned short *screenpos(const struct vc_data *vc, int offset,
 }
 
 /* Called  from the keyboard irq path.. */
+static DEFINE_SPINLOCK(scrolldelta_lock);
+
 static inline void scrolldelta(int lines)
 {
-	/* FIXME */
-	/* scrolldelta needs some kind of consistency lock, but the BKL was
-	   and still is not protecting versus the scheduled back end */
+	spin_lock(&scrolldelta_lock);
 	scrollback_delta += lines;
+	spin_unlock(&scrolldelta_lock);
 	schedule_console_callback();
 }
 
-- 
2.42.0