tty: BKL pushdown
- Push the BKL down into the line disciplines
- Switch the tty layer to unlocked_ioctl
- Introduce a new ctrl_lock spin lock for the control bits
- Eliminate much of the lock_kernel use in n_tty
- Prepare to (but don't yet) call the drivers with the lock dropped
on the paths that historically held the lock
BKL now primarily protects open/close/ldisc change in the tty layer
[jirislaby@gmail.com: a couple of fixes]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 1c26604..e64f0bf 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -2541,6 +2541,9 @@
if (get_user(type, p))
return -EFAULT;
ret = 0;
+
+ lock_kernel();
+
switch (type)
{
case TIOCL_SETSEL:
@@ -2560,7 +2563,7 @@
ret = sel_loadlut(p);
break;
case TIOCL_GETSHIFTSTATE:
-
+
/*
* Make it possible to react to Shift+Mousebutton.
* Note that 'shift_state' is an undocumented
@@ -2615,6 +2618,7 @@
ret = -EINVAL;
break;
}
+ unlock_kernel();
return ret;
}
@@ -3829,7 +3833,7 @@
goto out;
c = (font.width+7)/8 * 32 * font.charcount;
-
+
if (op->data && font.charcount > op->charcount)
rc = -ENOSPC;
if (!(op->flags & KD_FONT_FLAG_OLD)) {