On Thu, Jun 04, 2020 at 02:10:27PM +0800, Jason Wang wrote: > > > get_user(flags, desc->flags) > > > smp_rmb() > > > if (flags & VALID) > > > copy_from_user(&adesc, desc, sizeof adesc); > > > > > > this would be a good candidate I think. > > Perhaps, once we get stac/clac out of raw_copy_from_user() (coming cycle, > > probably). BTW, how large is the structure and how is it aligned? > > > Each descriptor is 16 bytes, and 16 bytes aligned.
Won't it be cheaper to grap the entire thing unconditionally? And what does that rmb order, while we are at it - won't all coherency work in terms of entire cachelines anyway? Confused...
