Function cpuset_setproc

freebsd/kern/kern_cpuset.c:1204–1329

* Handle four cases for updating an entire process. * * 1) Set is non-null and the process is not rebasing onto a new root. This * reparents all anonymous sets to the provided set and replaces all * non-anonymous td_cpusets with the provided set. * 2) Set is non-null and the process is rebasing onto a new root. This * creates a new base set if the process previously had its own ba

 * state.
 */
static int
cpuset_setproc(pid_t pid, struct cpuset *set, cpuset_t *mask,
    struct domainset *domain, bool rebase)
{
	struct setlist freelist;
	struct setlist droplist;
	struct domainlist domainlist;
	struct cpuset *base, *nset, *nroot, *tdroot;
	struct thread *td;
	struct proc *p;
	int needed;
	int nfree;
	int error;

	/*
	 * The algorithm requires two passes due to locking considerations.
	 * 
	 * 1) Lookup the process and acquire the locks in the required order.
	 * 2) If enough cpusets have not been allocated release the locks and
	 *    allocate them.  Loop.
	 */
	cpuset_freelist_init(&freelist, 1);
	domainset_freelist_init(&domainlist, 1);
	nfree = 1;
	LIST_INIT(&droplist);
	nfree = 0;
	base = set;
	nroot = NULL;
	if (set != NULL)
		nroot = cpuset_getroot(set);
	for (;;) {
		error = cpuset_which(CPU_WHICH_PID, pid, &p, &td, &nset);
		if (error)
			goto out;
		tdroot = cpuset_getroot(td->td_cpuset);
		needed = p->p_numthreads;
		if (set != NULL && rebase && tdroot != nroot)
			needed++;
		if (nfree >= needed)
			break;
		PROC_UNLOCK(p);
		if (nfree < needed) {
			cpuset_freelist_add(&freelist, needed - nfree);
			domainset_freelist_add(&domainlist, needed - nfree);
			nfree = needed;
		}
	}
	PROC_LOCK_ASSERT(p, MA_OWNED);

	/*
	 * If we're changing roots and the root set is what has been specified
	 * as the parent, then we'll check if the process was previously using
	 * the root set and, if it wasn't, create a new base with the process's
	 * mask applied to it.
	 *
	 * If the new root is incompatible with the existing mask, then we allow
	 * the process to take on the new root if and only if they have
	 * privilege to widen their mask anyways.  Unprivileged processes get