1*28524683SDavid du Colombier #include "../plan9/lib.h" 2272efad7SDavid du Colombier #include "../plan9/sys9.h" 3*28524683SDavid du Colombier #define _LOCK_EXTENSION 4272efad7SDavid du Colombier #include <lock.h> 5*28524683SDavid du Colombier //#include <lib9.h> 6272efad7SDavid du Colombier 7272efad7SDavid du Colombier void lock(Lock * l)8*28524683SDavid du Colombierlock(Lock *l) 9272efad7SDavid du Colombier { 10*28524683SDavid du Colombier if(ainc(&l->key) == 1) 11*28524683SDavid du Colombier return; /* changed from 0 -> 1: we hold lock */ 12*28524683SDavid du Colombier /* otherwise wait in kernel */ 13*28524683SDavid du Colombier while(_SEMACQUIRE(&l->sem, 1) < 0){ 14*28524683SDavid du Colombier /* interrupted; try again */ 15*28524683SDavid du Colombier } 16*28524683SDavid du Colombier } 17*28524683SDavid du Colombier 18*28524683SDavid du Colombier void unlock(Lock * l)19*28524683SDavid du Colombierunlock(Lock *l) 20*28524683SDavid du Colombier { 21*28524683SDavid du Colombier if(adec(&l->key) == 0) 22*28524683SDavid du Colombier return; /* changed from 1 -> 0: no contention */ 23*28524683SDavid du Colombier _SEMRELEASE(&l->sem, 1); 24272efad7SDavid du Colombier } 25272efad7SDavid du Colombier 26272efad7SDavid du Colombier int canlock(Lock * l)27*28524683SDavid du Colombiercanlock(Lock *l) 28272efad7SDavid du Colombier { 29*28524683SDavid du Colombier if(ainc(&l->key) == 1) 30*28524683SDavid du Colombier return 1; /* changed from 0 -> 1: success */ 31*28524683SDavid du Colombier /* Undo increment (but don't miss wakeup) */ 32*28524683SDavid du Colombier if(adec(&l->key) == 0) 33*28524683SDavid du Colombier return 0; /* changed from 1 -> 0: no contention */ 34*28524683SDavid du Colombier _SEMRELEASE(&l->sem, 1); 35272efad7SDavid du Colombier return 0; 36272efad7SDavid du Colombier } 37