rrm_held
boolean_t rrm_held(rrmlock_t *rrl, krw_t rw);
#define RRM_READ_HELD(x) rrm_held(x, RW_READER)
#define RRM_WRITE_HELD(x) rrm_held(x, RW_WRITER)
(rrm_held(x, RW_WRITER) || rrm_held(x, RW_READER))