Re: f_ops flag to speed up compatible ioctls in linux kernel

[Michael S. Tsirkin]

Quoting r. Roland Dreier (roland@xxxxxxxxxxx) "Re: f_ops flag to speed up compatible ioctls in linux kernel":
>     Roland> Yes, this is exactly right.  One issue raised by this
>     Roland> thread is that the ioctl32 compatibility code only allows
>     Roland> one compatibility handler per ioctl number.  It seems that
>     Roland> this creates all sorts of possibilities for mayhem because
>     Roland> it makes the ioctl namespace global in scope in some
>     Roland> situations.  Does anyone have any thoughts on if/how this
>     Roland> should be addressed?
> 
>     Michael> Thats what my original patch attempts to address
>     Michael> http://www.uwsg.indiana.edu/hypermail/linux/kernel/0409.0/0025.html
>     Michael> What do you think?
> 
> That patch seems somewhat orthogonal to the issue I raised.  You're
> just fixing the problem for devices that don't use the ioctl32 compat
> layer.
> 

No I'm removing the need for ioctls to go through the compat layer.
No compat layer, no problem.

I see the compat layer as a hack to support legacy devices without touching
all of their code.
I dont see why a new driver would use the compat hacks instead of simply
building a 32/64 bit compatible interface, and legacy drivers have the
uniqueness for commands solved one way or another.

So the only interesting problem left is for new char devices.

MST
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/