PCN_RUNNING
pcnp->pcn_flags &= ~PCN_RUNNING;
pcnp->pcn_flags &= ~PCN_RUNNING;
ASSERT(!(pcnp->pcn_flags & PCN_RUNNING));
pcnp->pcn_flags |= PCN_RUNNING;
#define IS_RUNNING(p) ((p)->pcn_flags & PCN_RUNNING)