vt: selection, introduce vc_is_sel

fix #25967152

commit dce05aa6eec977f1472abed95ccd71276b9a3864 upstream

Avoid global variables (namely sel_cons) by introducing vc_is_sel. It
checks whether the parameter is the current selection console. This will
help putting sel_cons to a struct later.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200219073951.16151-1-jslaby@suse.czSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYihao Wu <wuyihao@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

drivers/tty/vt/selection.c

@@ -83,6 +83,11 @@ void clear_selection(void)
 	}
 }
 
+bool vc_is_sel(struct vc_data *vc)
+{
+	return vc == sel_cons;
+}
+
 /*
  * User settable table: what characters are to be considered alphabetic?
  * 128 bits. Locked by the console lock.

drivers/tty/vt/vt.c

@@ -890,8 +890,9 @@ static void hide_softcursor(struct vc_data *vc)
 
 static void hide_cursor(struct vc_data *vc)
 {
-	if (vc == sel_cons)
+	if (vc_is_sel(vc))
 		clear_selection();
+
 	vc->vc_sw->con_cursor(vc, CM_ERASE);
 	hide_softcursor(vc);
 }
@@ -901,7 +902,7 @@ static void set_cursor(struct vc_data *vc)
 	if (!con_is_fg(vc) || console_blanked || vc->vc_mode == KD_GRAPHICS)
 		return;
 	if (vc->vc_deccm) {
-		if (vc == sel_cons)
+		if (vc_is_sel(vc))
 			clear_selection();
 		add_softcursor(vc);
 		if ((vc->vc_cursor_type & 0x0f) != 1)
@@ -1199,7 +1200,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 		}
 	}
 
-	if (vc == sel_cons)
+	if (vc_is_sel(vc))
 		clear_selection();
 
 	old_rows = vc->vc_rows;

drivers/tty/vt/vt_ioctl.c

@@ -43,7 +43,7 @@ char vt_dont_switch;
 extern struct tty_driver *console_driver;
 
 #define VT_IS_IN_USE(i)	(console_driver->ttys[i] && console_driver->ttys[i]->count)
-#define VT_BUSY(i)	(VT_IS_IN_USE(i) || i == fg_console || vc_cons[i].d == sel_cons)
+#define VT_BUSY(i)	(VT_IS_IN_USE(i) || i == fg_console || vc_is_sel(vc_cons[i].d))
 
 /*
  * Console (vt and kd) routines, as defined by USL SVR4 manual, and by

include/linux/selection.h

@@ -12,9 +12,7 @@
 #include <linux/vt_buffer.h>
 
 struct tty_struct;
-
-extern struct vc_data *sel_cons;
-struct tty_struct;
+struct vc_data;
 
 extern void clear_selection(void);
 extern int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty);
@@ -23,6 +21,8 @@ extern int sel_loadlut(char __user *p);
 extern int mouse_reporting(void);
 extern void mouse_report(struct tty_struct * tty, int butt, int mrx, int mry);
 
+bool vc_is_sel(struct vc_data *vc);
+
 extern int console_blanked;
 
 extern const unsigned char color_table[];