ref: b52598178143b1c4a154caec87037c3a717c3ddd
dir: /kern/rwlock.c/
#include "u.h" #include "lib.h" #include "dat.h" #include "fns.h" #include "error.h" void rlock(RWlock *l) { qlock(&l->x); /* wait here for writers and exclusion */ lock(&l->lk); l->readers++; canqlock(&l->k); /* block writers if we are the first reader */ unlock(&l->lk); qunlock(&l->x); } void runlock(RWlock *l) { lock(&l->lk); if(--l->readers == 0) /* last reader out allows writers */ qunlock(&l->k); unlock(&l->lk); } void wlock(RWlock *l) { qlock(&l->x); /* wait here for writers and exclusion */ qlock(&l->k); /* wait here for last reader */ } void wunlock(RWlock *l) { qunlock(&l->k); qunlock(&l->x); }