Re: ioctl cleanups: enable sg_io and serial stuff to be shared

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > Not sure if we are not too close to stable release to do that? And I
> > see no incremental way how to get there. Moving compatibility stuff
> > closer to drivers can be done close to stable release...
> 
> You can define it as follows:
> 
> 1) If entry exists in COMPAT or TRANSLATE table, invoke
>    fops->ioctl(), else
> 
> 2) If ->compat_ioctl() exists, invoke that, else
> 
> 3) Fail.
> 
> The COMPAT tables are sort of valuable, in that it eliminates
> the need to duplicate code when all of a drivers ioctls need
> no translation.
> 
> BTW, need to extend this to netdev->do_ioctl as well for the
> handling of SIOCDEVPRIVATE based stuff.  Oh goody, we can finally
> fix up that crap :))))

There's a *lot* of structs that contain *ioctl:
pavel@amd:/usr/src/linux-test/include/linux$ grep "*ioctl" *
pavel@amd:/usr/src/linux-test/include/linux$ grep "*ioctl" *
atmdev.h:       int (*ioctl)(struct atm_dev *dev,unsigned int cmd,void *arg);
atmdev.h:       int (*ioctl)(struct atm_dev *dev,unsigned int cmd,void *arg);
fs.h:   int (*ioctl) (struct inode *, struct file *, unsigned, unsigned long);
fs.h:   int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
hdlc.h: int (*ioctl)(struct net_device *dev, struct ifreq *ifr, int cmd);
hdlcdrv.h:      int (*ioctl)(struct net_device *, struct ifreq *,
ide.h:  int             (*ioctl)(ide_drive_t *, struct inode *, struct file *, unsigned int, unsigned long);
if_bridge.h:extern void brioctl_set(int (*ioctl_hook)(unsigned long));
if_pppox.h:     int             (*ioctl)(struct socket *sock, unsigned int cmd,
ioctl32.h:typedef int (*ioctl_trans_handler_t)(unsigned int, unsigned int, unsigned long, struct file *);
loop.h: int             (*ioctl)(struct loop_device *, int cmd,
loop.h: int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
net.h:  int             (*ioctl)     (struct socket *sock, unsigned int cmd,
ppp_channel.h:  int     (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
serial_core.h:  int             (*ioctl)(struct uart_port *, unsigned int, unsigned long);
tty_driver.h: * int  (*ioctl)(struct tty_struct *tty, struct file * file,
tty_driver.h:   int  (*ioctl)(struct tty_struct *tty, struct file * file,
tty_ldisc.h: * int      (*ioctl)(struct tty_struct * tty, struct file * file,
tty_ldisc.h:    int     (*ioctl)(struct tty_struct * tty, struct file * file,
usb.h:  int (*ioctl) (struct usb_interface *intf, unsigned int code, void *buf);
wanrouter.h:    int (*ioctl) (struct wan_device *wandev, unsigned cmd,
pavel@amd:/usr/src/linux-test/include/linux$

What about this one: redefine it to (*ioctl)( ...., unsigned *long*,
unsinged long). That means we can add 

#define IOCTL_COMPAT 0x1 0000 0000

and avoid adding new field to each such structure. Also I will not
have to duplicate lots of middle-level code (I will have to modify
unsigned int -> unsigned long, but no second copies of everything). It
means that architecture with CONFIG_COMPAT needs to have unsigned long
> 32 bits, but I guess we can live with that.

What do you think?
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]