On Tue, 23 Sep 2014, LF.Tan wrote:
> On Mon, Sep 8, 2014 at 5:22 PM, Ley Foon Tan <lftan@xxxxxxxxxx> wrote:
> > Follow m68k futex implementation for !CONFIG_SMP.
Great. Follow arch/random implementation blindly and copy all the bugs
in it.
> > +static inline int
> > +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
> > + u32 oldval, u32 newval)
> > +{
> > + u32 val;
> > +
> > + if (unlikely(get_user(val, uaddr) != 0))
> > + return -EFAULT;
> > +
> > + if (val == oldval && unlikely(put_user(newval, uaddr) != 0))
> > + return -EFAULT;
> > +
> > + *uval = val;
> > +
> > + return 0;
> > +}
Care to explain how this works reliably and resembles proper cmpxchg
semantics under all circumstances?
Thanks,
tglx
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