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#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);
}
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