#define lookup(_daddr,_stack) \
({ \
struct inet_peer *u, **v; \
- if (_stack) { \
+ if (_stack != NULL) { \
stackptr = _stack; \
*stackptr++ = &peer_root; \
} \
v = &u->avl_left; \
else \
v = &u->avl_right; \
- if (_stack) \
+ if (_stack != NULL) \
*stackptr++ = v; \
u = *v; \
} \