change semantics of ldisc ->compat_ioctl()

First of all, make it return int.  Returning long when native method
had never allowed that is ridiculous and inconvenient.

More importantly, change the caller; if ldisc ->compat_ioctl() is NULL
or returns -ENOIOCTLCMD, tty_compat_ioctl() will try to feed cmd and
compat_ptr(arg) to ldisc's native ->ioctl().

That simplifies ->compat_ioctl() instances quite a bit - they only
need to deal with ioctls that are neither generic tty ones (those
would get shunted off to tty_ioctl()) nor simple compat pointer ones.

Note that something like TCFLSH won't reach ->compat_ioctl(),
even if ldisc ->ioctl() does handle it - it will be recognized
earlier and passed to tty_ioctl() (and ultimately - ldisc ->ioctl()).

For many ldiscs it means that NULL ->compat_ioctl() does the
right thing.  Those where it won't serve (see e.g. n_r3964.c) are
also easily dealt with - we need to handle the numeric-argument
ioctls (calling the native instance) and, if such would exist,
the ioctls that need layout conversion, etc.

All in-tree ldiscs dealt with.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 963bb0309e25..ae0dd57a8e99 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -821,6 +821,7 @@ static int __init hci_uart_init(void)
 	hci_uart_ldisc.read		= hci_uart_tty_read;
 	hci_uart_ldisc.write		= hci_uart_tty_write;
 	hci_uart_ldisc.ioctl		= hci_uart_tty_ioctl;
+	hci_uart_ldisc.compat_ioctl	= hci_uart_tty_ioctl;
 	hci_uart_ldisc.poll		= hci_uart_tty_poll;
 	hci_uart_ldisc.receive_buf	= hci_uart_tty_receive;
 	hci_uart_ldisc.write_wakeup	= hci_uart_tty_wakeup;