Re: [PATCH 4/4] x86/fpu: don't abuse drop_init_fpu() in flush_thread()

Oleg Nesterov
2015-03-14T14:50:10Z

On 03/13, Borislav Petkov wrote:
>
> On Fri, Mar 13, 2015 at 05:26:54PM +0100, Oleg Nesterov wrote:
> > > One example where drop_init_fpu() seems to make sense is
> > > __kernel_fpu_end(): kernel is done with FPU and current was using the
> > > FPU prior so let's restore it for the eagerfpu case.
> >
> > No, no, this is another case or I misunderstood you.
> >
> > __kernel_fpu_end() needs to restore FPU from current's fpu->state exactly
> > because current used FPU prior. And that state was saved by __save_init_fpu()
> > in __kernel_fpu_begin().
>
> That's exactly what I mean. See: "... kernel is done with FPU and current was
> using the FPU prior..."

Yes, but my point was that this is why we can _not_ use drop_init_fpu() in
__kernel_fpu_end().

Nevermind, look like I really misunderstood you.

Oleg.