bsd/kern/kern_proc.c

2394         struct pgrp * oldpg;
2407 	oldpg = p->p_pgrp;
2408 	if (oldpg == PGRP_NULL)
2409 		panic("pgrp_replace: oldpg NULL");
2410 	oldpg->pg_refcount++;
2421        pgrp_lock(oldpg);
2422        oldpg->pg_membercnt--;
2423        if (oldpg->pg_membercnt < 0)
2424                 panic("pgprp: -ve membercnt pgprp:%p p:%p\n",oldpg, p);
2426         if (oldpg->pg_members.lh_first == 0) {
2427                 pgrp_unlock(oldpg);
2428                 pgdelete_dropref(oldpg);
2430                 pgrp_unlock(oldpg);
2431                 pg_rele(oldpg);