rw_downgrade
rw_downgrade(&mw->mw_lock);
#define LLE_DOWNGRADE(lle) rw_downgrade(&(lle)->lle_lock)
#define INP_DOWNGRADE(inp) rw_downgrade(&(inp)->inp_lock)
# define MUTEX_DOWNGRADE(x) rw_downgrade(&(x)->ipf_lk)
rw_downgrade(&moea64_eviction_lock);
rw_downgrade(&(object)->lock)