On Thu, Apr 30, 2020 at 08:39:00AM +0800, Jeremy Kerr wrote: > Hi Christophe, > > > > Just use the proper non __-prefixed get/put_user variants where > > > that is not done yet. > > > > But it means you are doing the access_ok() check everytime, which is > > what is to be avoided by doing the access_ok() once then using the > > __-prefixed variant. > > 5 out of 8 of these are just a access_ok(); simple_read_from_buffer(). > > For the cases where it's multiple __put/get_user()s, the max will be 5. > (for the mbox access). Is that worth optimising the access_ok() checks?
access_ok is just trivial comparism to the segment limit, I don't think it has a relavant performance impact.
