David Howells <dhowells@xxxxxxxxxx> wrote:
> Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>
> > static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x)
> > {
> > - return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK);
> > + return (void *)((unsigned long)READ_ONCE(x) & /* Address dependency. */
> > + ~ASSOC_ARRAY_PTR_TYPE_MASK);
> > }
>
> This is the wrong place to do this. assoc_array_ptr_to_leaf() is effectively
> no more than a special cast; it removes a metadata bit from a pointer. x is
> the value we're modifying, not *x, and x was read by the caller.
Also, x is not a pointer you can read from, so if READ_ONCE(x) ever effects a
memory access, you might get an oops.
David
