1*ce95e1b3SDavid du Colombier #include "../plan9/lib.h" 2*ce95e1b3SDavid du Colombier #include "../plan9/sys9.h" 3*ce95e1b3SDavid du Colombier #define _LOCK_EXTENSION 4*ce95e1b3SDavid du Colombier #include <lock.h> 5*ce95e1b3SDavid du Colombier //#include <lib9.h> 6*ce95e1b3SDavid du Colombier 7*ce95e1b3SDavid du Colombier void lock(Lock * l)8*ce95e1b3SDavid du Colombierlock(Lock *l) 9*ce95e1b3SDavid du Colombier { 10*ce95e1b3SDavid du Colombier if(ainc(&l->key) == 1) 11*ce95e1b3SDavid du Colombier return; /* changed from 0 -> 1: we hold lock */ 12*ce95e1b3SDavid du Colombier /* otherwise wait in kernel */ 13*ce95e1b3SDavid du Colombier while(_SEMACQUIRE(&l->sem, 1) < 0){ 14*ce95e1b3SDavid du Colombier /* interrupted; try again */ 15*ce95e1b3SDavid du Colombier } 16*ce95e1b3SDavid du Colombier } 17*ce95e1b3SDavid du Colombier 18*ce95e1b3SDavid du Colombier void unlock(Lock * l)19*ce95e1b3SDavid du Colombierunlock(Lock *l) 20*ce95e1b3SDavid du Colombier { 21*ce95e1b3SDavid du Colombier if(adec(&l->key) == 0) 22*ce95e1b3SDavid du Colombier return; /* changed from 1 -> 0: no contention */ 23*ce95e1b3SDavid du Colombier _SEMRELEASE(&l->sem, 1); 24*ce95e1b3SDavid du Colombier } 25*ce95e1b3SDavid du Colombier 26*ce95e1b3SDavid du Colombier int canlock(Lock * l)27*ce95e1b3SDavid du Colombiercanlock(Lock *l) 28*ce95e1b3SDavid du Colombier { 29*ce95e1b3SDavid du Colombier if(ainc(&l->key) == 1) 30*ce95e1b3SDavid du Colombier return 1; /* changed from 0 -> 1: success */ 31*ce95e1b3SDavid du Colombier /* Undo increment (but don't miss wakeup) */ 32*ce95e1b3SDavid du Colombier if(adec(&l->key) == 0) 33*ce95e1b3SDavid du Colombier return 0; /* changed from 1 -> 0: no contention */ 34*ce95e1b3SDavid du Colombier _SEMRELEASE(&l->sem, 1); 35*ce95e1b3SDavid du Colombier return 0; 36*ce95e1b3SDavid du Colombier } 37