1*12b1df16SDavid du Colombier #include "../plan9/lib.h" 2*12b1df16SDavid du Colombier #include "../plan9/sys9.h" 3*12b1df16SDavid du Colombier #define _LOCK_EXTENSION 4*12b1df16SDavid du Colombier #include <lock.h> 5*12b1df16SDavid du Colombier //#include <lib9.h> 6*12b1df16SDavid du Colombier 7*12b1df16SDavid du Colombier void lock(Lock * l)8*12b1df16SDavid du Colombierlock(Lock *l) 9*12b1df16SDavid du Colombier { 10*12b1df16SDavid du Colombier if(ainc(&l->key) == 1) 11*12b1df16SDavid du Colombier return; /* changed from 0 -> 1: we hold lock */ 12*12b1df16SDavid du Colombier /* otherwise wait in kernel */ 13*12b1df16SDavid du Colombier while(_SEMACQUIRE(&l->sem, 1) < 0){ 14*12b1df16SDavid du Colombier /* interrupted; try again */ 15*12b1df16SDavid du Colombier } 16*12b1df16SDavid du Colombier } 17*12b1df16SDavid du Colombier 18*12b1df16SDavid du Colombier void unlock(Lock * l)19*12b1df16SDavid du Colombierunlock(Lock *l) 20*12b1df16SDavid du Colombier { 21*12b1df16SDavid du Colombier if(adec(&l->key) == 0) 22*12b1df16SDavid du Colombier return; /* changed from 1 -> 0: no contention */ 23*12b1df16SDavid du Colombier _SEMRELEASE(&l->sem, 1); 24*12b1df16SDavid du Colombier } 25*12b1df16SDavid du Colombier 26*12b1df16SDavid du Colombier int canlock(Lock * l)27*12b1df16SDavid du Colombiercanlock(Lock *l) 28*12b1df16SDavid du Colombier { 29*12b1df16SDavid du Colombier if(ainc(&l->key) == 1) 30*12b1df16SDavid du Colombier return 1; /* changed from 0 -> 1: success */ 31*12b1df16SDavid du Colombier /* Undo increment (but don't miss wakeup) */ 32*12b1df16SDavid du Colombier if(adec(&l->key) == 0) 33*12b1df16SDavid du Colombier return 0; /* changed from 1 -> 0: no contention */ 34*12b1df16SDavid du Colombier _SEMRELEASE(&l->sem, 1); 35*12b1df16SDavid du Colombier return 0; 36*12b1df16SDavid du Colombier } 37