David Howells <[email protected]> wrote: > Paul E. McKenney <[email protected]> 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
