On Mon, Jun 19, 2017 at 10:15:09AM -0600, Jordan Crouse wrote: > A number of us over in DRM land have been using __u64 scalar types > to store pointers for uapi structures in accordance with Daniel Vetter's > now classic treatise on ioctls: > > http://blog.ffwll.ch/2013/11/botching-up-ioctls.html > > A smaller number of us have further been marking the __u64 with __user, > to wit: > > struct uapistruct { > ... > __u64 __user myptr; > --- > }; It wouldn't make sense to have this: struct uapistruct { __u64 __user myptr; __u64 anothermember; }; In other words, eiter all members are in the user address space or none are. So, a struct member should not be marked __user (exactly as for 'const' or 'volatile'). It wouldn't also make sense to move the __user to the whole struct, giving something like: struct uapistruct { __u64 myptr; __u64 anothermember; } __user; because it's not the type that belong to the user address space but some specific objects. Of course, your real problem here is that you're using a __u64 to store a pointer and then expect this __u64 to have some properties unique to pointers. -- Luc Van Oostenryck (sparse hacker) _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
