On Mon, 2026-07-20 at 21:06 +0200, Johannes Berg wrote:
> On Mon, 2026-07-20 at 20:26 +0200, Johannes Berg wrote:
> >
> > +static inline int
> > +arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user
> > *uaddr)
> > +{
> > + u32 oldval, newval;
> > + u32 *p = (u32 __force *)uaddr;
> > +
> > + do {
> > + oldval = READ_ONCE(*p);
> > +
> > + switch (op) {
> > + case FUTEX_OP_SET:
> > + newval = oparg;
> > + break;
> > + case FUTEX_OP_ADD:
> > + newval = oldval + oparg;
> > + break;
> > + case FUTEX_OP_OR:
> > + newval = oldval | oparg;
> > + break;
> > + case FUTEX_OP_ANDN:
> > + newval = oldval & ~oparg;
> > + break;
> > + case FUTEX_OP_XOR:
> > + newval = oldval ^ oparg;
> > + break;
> > + default:
> > + return -ENOSYS;
> > + }
> > + } while (!try_cmpxchg(p, &oldval, newval));
> > +
> > + *oval = oldval;
>
> Wait ... this is also garbage, it should just be the switch() and then
>
> *oval = cmpxchg(p, oldval, newval);
>
> not the loop...
Err, no. But our uaccess.c implementation here also seems wrong and
should be more like this one?
OK I'm confused, but I think we need to clean up uaccess.c before
implementing this for real...
johannes
