On Tue, Oct 08, 2019 at 08:58:58PM +0100, Al Viro wrote: > The difference is, they have separate "for read" and "for write" primitives > and they want the range in their user_access_end() analogue. Separating > the read and write isn't a problem for callers (we want them close to > the actual memory accesses). Passing the range to user_access_end() just > might be tolerable, unless it makes you throw up... NOTE: I'm *NOT* suggesting to bring back the VERIFY_READ/VERIFY_WRITE argument to access_ok(). We'd gotten rid of it, and for a very good reason (and decades overdue). The main difference between access_ok() and user_access_begin() is that the latter is right next to actual memory access, with user_access_end() on the other side, also very close. And most of those guys would be concentrated in a few functions, where we bloody well know which direction we are copying. Even if we try and map ppc allow_..._to_user() on user_access_begin(), access_ok() remains as it is (and I hope we'll get rid of the majority of its caller in process).
