Messages in this thread | | | Date | Tue, 18 Sep 2018 11:59:52 -0600 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v2 05/17] compat_ioctl: move more drivers to generic_compat_ioctl_ptrarg |
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On Tue, Sep 18, 2018 at 10:51:08AM -0700, Darren Hart wrote: > On Fri, Sep 14, 2018 at 09:57:48PM +0100, Al Viro wrote: > > On Fri, Sep 14, 2018 at 01:35:06PM -0700, Darren Hart wrote: > > > > > Acked-by: Darren Hart (VMware) <dvhart@infradead.org> > > > > > > As for a longer term solution, would it be possible to init fops in such > > > a way that the compat_ioctl call defaults to generic_compat_ioctl_ptrarg > > > so we don't have to duplicate this boilerplate for every ioctl fops > > > structure? > > > > Bad idea, that... Because several years down the road somebody will add > > an ioctl that takes an unsigned int for argument. Without so much as looking > > at your magical mystery macro being used to initialize file_operations. > > Fair, being explicit in the declaration as it is currently may be > preferable then.
It would be much cleaner and safer if you could arrange things to add something like this to struct file_operations:
long (*ptr_ioctl) (struct file *, unsigned int, void __user *);
Where the core code automatically converts the unsigned long to the void __user * as appropriate.
Then it just works right always and the compiler will help address Al's concern down the road.
Cheers, Jason
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