[PATCH] Console blanking locking fix
I've had WARN_CONSOLE_UNLOCKED warnings when calling TIOCLINUX
TIOCL_BLANKSCREEN and TIOCL_UNBLANKSCREEN.
(I'm blind and I use a braille display. I use those functions to blank my
laptop's screen so people don't read it, and hopefully to conserve power.)
The warnings are from these places:
do_blank_screen at drivers/char/vt.c:2754 (Not tainted)
save_screen at drivers/char/vt.c:575 (Not tainted)
do_unblank_screen at drivers/char/vt.c:2822 (Not tainted)
set_palette at drivers/char/vt.c:2908 (Not tainted)
At a glance I would think the following patch ought to fix that. Tested on
one machine. Could you please tell me if this is correct and/or forward
the patch where appropriate...
Signed-off-by: Stephane Doyon <s.doyon@videotron.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 665103c..27b6c29 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -2272,7 +2272,9 @@
ret = paste_selection(tty);
break;
case TIOCL_UNBLANKSCREEN:
+ acquire_console_sem();
unblank_screen();
+ release_console_sem();
break;
case TIOCL_SELLOADLUT:
ret = sel_loadlut(p);
@@ -2317,8 +2319,10 @@
}
break;
case TIOCL_BLANKSCREEN: /* until explicitly unblanked, not only poked */
+ acquire_console_sem();
ignore_poke = 1;
do_blank_screen(0);
+ release_console_sem();
break;
case TIOCL_BLANKEDSCREEN:
ret = console_blanked;