145    struct _Lock {  struct
147       struct _Lock* admin_next; /* fields for a double linked */  argument
148       struct _Lock* admin_prev; /* list of these locks */  argument
149       ULong         unique; /* used for persistence-hashing */
150       UInt          magic;  /* LockN_MAGIC or LockP_MAGIC */
153       ExeContext*   appeared_at;
157       ExeContext*   acquired_at;
159       SO*           hbso;      /* associated SO */
160       Addr          guestaddr; /* Guest address of lock */
161       LockKind      kind;      /* what kind of lock this is */
163       Bool          heldW; 
164       WordBag*      heldBy; /* bag of threads that hold this lock */