On Thu, Oct 21, 2021 at 11:40 AM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
> + map_type = READ_ONCE(array->aux->type);
> + if (!map_type) {
> + /* There's no owner yet where we could check for compatibility.
> + * Do an atomic swap to prevent racing with another invocation
> + * of this branch (via simultaneous map_update syscalls).
> */
> - array->aux->type = fp->type;
> - array->aux->jited = fp->jited;
> + if (cmpxchg(&array->aux->type, 0, prog_type))
> + return false;
Other fields might be used in the compatibility check in the future.
This hack is too fragile.
Just use a spin_lock.
