FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_cpuset.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2008,  Jeffrey Roberson <jeff@freebsd.org>
      * All rights reserved.
      * 
      * Copyright (c) 2008 Nokia Corporation
      * All rights reserved.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice unmodified, this list of conditions, and the following
     *    disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_ddb.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/sysctl.h>
    #include <sys/ctype.h>
    #include <sys/sysproto.h>
    #include <sys/jail.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/priv.h>
    #include <sys/proc.h>
    #include <sys/refcount.h>
    #include <sys/sched.h>
    #include <sys/smp.h>
    #include <sys/syscallsubr.h>
    #include <sys/capsicum.h>
    #include <sys/cpuset.h>
    #include <sys/domainset.h>
    #include <sys/sx.h>
    #include <sys/queue.h>
    #include <sys/libkern.h>
    #include <sys/limits.h>
    #include <sys/bus.h>
    #include <sys/interrupt.h>
    #include <sys/vmmeter.h>
    
    #include <vm/uma.h>
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pageout.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_param.h>
    #include <vm/vm_phys.h>
    #include <vm/vm_pagequeue.h>
    
    #ifdef DDB
    #include <ddb/ddb.h>
    #endif /* DDB */
    
    /*
     * cpusets provide a mechanism for creating and manipulating sets of
     * processors for the purpose of constraining the scheduling of threads to
     * specific processors.
     *
     * Each process belongs to an identified set, by default this is set 1.  Each
     * thread may further restrict the cpus it may run on to a subset of this
     * named set.  This creates an anonymous set which other threads and processes
     * may not join by number.
     *
     * The named set is referred to herein as the 'base' set to avoid ambiguity.
     * This set is usually a child of a 'root' set while the anonymous set may
     * simply be referred to as a mask.  In the syscall api these are referred to
     * as the ROOT, CPUSET, and MASK levels where CPUSET is called 'base' here.
     *
     * Threads inherit their set from their creator whether it be anonymous or
     * not.  This means that anonymous sets are immutable because they may be
     * shared.  To modify an anonymous set a new set is created with the desired
     * mask and the same parent as the existing anonymous set.  This gives the
     * illusion of each thread having a private mask.
     *
    * Via the syscall apis a user may ask to retrieve or modify the root, base,
    * or mask that is discovered via a pid, tid, or setid.  Modifying a set
    * modifies all numbered and anonymous child sets to comply with the new mask.
    * Modifying a pid or tid's mask applies only to that tid but must still
    * exist within the assigned parent set.
    *
    * A thread may not be assigned to a group separate from other threads in
    * the process.  This is to remove ambiguity when the setid is queried with
    * a pid argument.  There is no other technical limitation.
    *
    * This somewhat complex arrangement is intended to make it easy for
    * applications to query available processors and bind their threads to
    * specific processors while also allowing administrators to dynamically
    * reprovision by changing sets which apply to groups of processes.
    *
    * A simple application should not concern itself with sets at all and
    * rather apply masks to its own threads via CPU_WHICH_TID and a -1 id
    * meaning 'curthread'.  It may query available cpus for that tid with a
    * getaffinity call using (CPU_LEVEL_CPUSET, CPU_WHICH_PID, -1, ...).
    */
   
   LIST_HEAD(domainlist, domainset);
   struct domainset __read_mostly domainset_fixed[MAXMEMDOM];
   struct domainset __read_mostly domainset_prefer[MAXMEMDOM];
   struct domainset __read_mostly domainset_roundrobin;
   
   static uma_zone_t cpuset_zone;
   static uma_zone_t domainset_zone;
   static struct mtx cpuset_lock;
   static struct setlist cpuset_ids;
   static struct domainlist cpuset_domains;
   static struct unrhdr *cpuset_unr;
   static struct cpuset *cpuset_zero, *cpuset_default, *cpuset_kernel;
   static struct domainset domainset0, domainset2;
   
   /* Return the size of cpuset_t at the kernel level */
   SYSCTL_INT(_kern_sched, OID_AUTO, cpusetsize, CTLFLAG_RD | CTLFLAG_CAPRD,
       SYSCTL_NULL_INT_PTR, sizeof(cpuset_t), "sizeof(cpuset_t)");
   
   cpuset_t *cpuset_root;
   cpuset_t cpuset_domain[MAXMEMDOM];
   
   static int domainset_valid(const struct domainset *, const struct domainset *);
   
   /*
    * Find the first non-anonymous set starting from 'set'.
    */
   static struct cpuset *
   cpuset_getbase(struct cpuset *set)
   {
   
           if (set->cs_id == CPUSET_INVALID)
                   set = set->cs_parent;
           return (set);
   }
   
   /*
    * Walks up the tree from 'set' to find the root.
    */
   static struct cpuset *
   cpuset_getroot(struct cpuset *set)
   {
   
           while ((set->cs_flags & CPU_SET_ROOT) == 0 && set->cs_parent != NULL)
                   set = set->cs_parent;
           return (set);
   }
   
   /*
    * Acquire a reference to a cpuset, all pointers must be tracked with refs.
    */
   struct cpuset *
   cpuset_ref(struct cpuset *set)
   {
   
           refcount_acquire(&set->cs_ref);
           return (set);
   }
   
   /*
    * Walks up the tree from 'set' to find the root.  Returns the root
    * referenced.
    */
   static struct cpuset *
   cpuset_refroot(struct cpuset *set)
   {
   
           return (cpuset_ref(cpuset_getroot(set)));
   }
   
   /*
    * Find the first non-anonymous set starting from 'set'.  Returns this set
    * referenced.  May return the passed in set with an extra ref if it is
    * not anonymous. 
    */
   static struct cpuset *
   cpuset_refbase(struct cpuset *set)
   {
   
           return (cpuset_ref(cpuset_getbase(set)));
   }
   
   /*
    * Release a reference in a context where it is safe to allocate.
    */
   void
   cpuset_rel(struct cpuset *set)
   {
           cpusetid_t id;
   
           if (refcount_release_if_not_last(&set->cs_ref))
                   return;
           mtx_lock_spin(&cpuset_lock);
           if (!refcount_release(&set->cs_ref)) {
                   mtx_unlock_spin(&cpuset_lock);
                   return;
           }
           LIST_REMOVE(set, cs_siblings);
           id = set->cs_id;
           if (id != CPUSET_INVALID)
                   LIST_REMOVE(set, cs_link);
           mtx_unlock_spin(&cpuset_lock);
           cpuset_rel(set->cs_parent);
           uma_zfree(cpuset_zone, set);
           if (id != CPUSET_INVALID)
                   free_unr(cpuset_unr, id);
   }
   
   /*
    * Deferred release must be used when in a context that is not safe to
    * allocate/free.  This places any unreferenced sets on the list 'head'.
    */
   static void
   cpuset_rel_defer(struct setlist *head, struct cpuset *set)
   {
   
           if (refcount_release_if_not_last(&set->cs_ref))
                   return;
           mtx_lock_spin(&cpuset_lock);
           if (!refcount_release(&set->cs_ref)) {
                   mtx_unlock_spin(&cpuset_lock);
                   return;
           }
           LIST_REMOVE(set, cs_siblings);
           if (set->cs_id != CPUSET_INVALID)
                   LIST_REMOVE(set, cs_link);
           LIST_INSERT_HEAD(head, set, cs_link);
           mtx_unlock_spin(&cpuset_lock);
   }
   
   /*
    * Complete a deferred release.  Removes the set from the list provided to
    * cpuset_rel_defer.
    */
   static void
   cpuset_rel_complete(struct cpuset *set)
   {
           cpusetid_t id;
   
           id = set->cs_id;
           LIST_REMOVE(set, cs_link);
           cpuset_rel(set->cs_parent);
           uma_zfree(cpuset_zone, set);
           if (id != CPUSET_INVALID)
                   free_unr(cpuset_unr, id);
   }
   
   /*
    * Find a set based on an id.  Returns it with a ref.
    */
   static struct cpuset *
   cpuset_lookup(cpusetid_t setid, struct thread *td)
   {
           struct cpuset *set;
   
           if (setid == CPUSET_INVALID)
                   return (NULL);
           mtx_lock_spin(&cpuset_lock);
           LIST_FOREACH(set, &cpuset_ids, cs_link)
                   if (set->cs_id == setid)
                           break;
           if (set)
                   cpuset_ref(set);
           mtx_unlock_spin(&cpuset_lock);
   
           KASSERT(td != NULL, ("[%s:%d] td is NULL", __func__, __LINE__));
           if (set != NULL && jailed(td->td_ucred)) {
                   struct cpuset *jset, *tset;
   
                   jset = td->td_ucred->cr_prison->pr_cpuset;
                   for (tset = set; tset != NULL; tset = tset->cs_parent)
                           if (tset == jset)
                                   break;
                   if (tset == NULL) {
                           cpuset_rel(set);
                           set = NULL;
                   }
           }
   
           return (set);
   }
   
   /*
    * Initialize a set in the space provided in 'set' with the provided parameters.
    * The set is returned with a single ref.  May return EDEADLK if the set
    * will have no valid cpu based on restrictions from the parent.
    */
   static int
   cpuset_init(struct cpuset *set, struct cpuset *parent,
       const cpuset_t *mask, struct domainset *domain, cpusetid_t id)
   {
   
           if (domain == NULL)
                   domain = parent->cs_domain;
           if (mask == NULL)
                   mask = &parent->cs_mask;
           if (!CPU_OVERLAP(&parent->cs_mask, mask))
                   return (EDEADLK);
           /* The domain must be prepared ahead of time. */
           if (!domainset_valid(parent->cs_domain, domain))
                   return (EDEADLK);
           CPU_COPY(mask, &set->cs_mask);
           LIST_INIT(&set->cs_children);
           refcount_init(&set->cs_ref, 1);
           set->cs_flags = 0;
           mtx_lock_spin(&cpuset_lock);
           set->cs_domain = domain;
           CPU_AND(&set->cs_mask, &parent->cs_mask);
           set->cs_id = id;
           set->cs_parent = cpuset_ref(parent);
           LIST_INSERT_HEAD(&parent->cs_children, set, cs_siblings);
           if (set->cs_id != CPUSET_INVALID)
                   LIST_INSERT_HEAD(&cpuset_ids, set, cs_link);
           mtx_unlock_spin(&cpuset_lock);
   
           return (0);
   }
   
   /*
    * Create a new non-anonymous set with the requested parent and mask.  May
    * return failures if the mask is invalid or a new number can not be
    * allocated.
    *
    * If *setp is not NULL, then it will be used as-is.  The caller must take
    * into account that *setp will be inserted at the head of cpuset_ids and
    * plan any potentially conflicting cs_link usage accordingly.
    */
   static int
   cpuset_create(struct cpuset **setp, struct cpuset *parent, const cpuset_t *mask)
   {
           struct cpuset *set;
           cpusetid_t id;
           int error;
           bool dofree;
   
           id = alloc_unr(cpuset_unr);
           if (id == -1)
                   return (ENFILE);
           dofree = (*setp == NULL);
           if (*setp != NULL)
                   set = *setp;
           else
                   *setp = set = uma_zalloc(cpuset_zone, M_WAITOK | M_ZERO);
           error = cpuset_init(set, parent, mask, NULL, id);
           if (error == 0)
                   return (0);
           free_unr(cpuset_unr, id);
           if (dofree)
                   uma_zfree(cpuset_zone, set);
   
           return (error);
   }
   
   static void
   cpuset_freelist_add(struct setlist *list, int count)
   {
           struct cpuset *set;
           int i;
   
           for (i = 0; i < count; i++) {
                   set = uma_zalloc(cpuset_zone, M_ZERO | M_WAITOK);
                   LIST_INSERT_HEAD(list, set, cs_link);
           }
   }
   
   static void
   cpuset_freelist_init(struct setlist *list, int count)
   {
   
           LIST_INIT(list);
           cpuset_freelist_add(list, count);
   }
   
   static void
   cpuset_freelist_free(struct setlist *list)
   {
           struct cpuset *set;
   
           while ((set = LIST_FIRST(list)) != NULL) {
                   LIST_REMOVE(set, cs_link);
                   uma_zfree(cpuset_zone, set);
           }
   }
   
   static void
   domainset_freelist_add(struct domainlist *list, int count)
   {
           struct domainset *set;
           int i;
   
           for (i = 0; i < count; i++) {
                   set = uma_zalloc(domainset_zone, M_ZERO | M_WAITOK);
                   LIST_INSERT_HEAD(list, set, ds_link);
           }
   }
   
   static void
   domainset_freelist_init(struct domainlist *list, int count)
   {
   
           LIST_INIT(list);
           domainset_freelist_add(list, count);
   }
   
   static void
   domainset_freelist_free(struct domainlist *list)
   {
           struct domainset *set;
   
           while ((set = LIST_FIRST(list)) != NULL) {
                   LIST_REMOVE(set, ds_link);
                   uma_zfree(domainset_zone, set);
           }
   }
   
   /* Copy a domainset preserving mask and policy. */
   static void
   domainset_copy(const struct domainset *from, struct domainset *to)
   {
   
           DOMAINSET_COPY(&from->ds_mask, &to->ds_mask);
           to->ds_policy = from->ds_policy;
           to->ds_prefer = from->ds_prefer;
   }
   
   /* Return 1 if mask and policy are equal, otherwise 0. */
   static int
   domainset_equal(const struct domainset *one, const struct domainset *two)
   {
   
           return (DOMAINSET_CMP(&one->ds_mask, &two->ds_mask) == 0 &&
               one->ds_policy == two->ds_policy &&
               one->ds_prefer == two->ds_prefer);
   }
   
   /* Return 1 if child is a valid subset of parent. */
   static int
   domainset_valid(const struct domainset *parent, const struct domainset *child)
   {
           if (child->ds_policy != DOMAINSET_POLICY_PREFER)
                   return (DOMAINSET_SUBSET(&parent->ds_mask, &child->ds_mask));
           return (DOMAINSET_ISSET(child->ds_prefer, &parent->ds_mask));
   }
   
   static int
   domainset_restrict(const struct domainset *parent,
       const struct domainset *child)
   {
           if (child->ds_policy != DOMAINSET_POLICY_PREFER)
                   return (DOMAINSET_OVERLAP(&parent->ds_mask, &child->ds_mask));
           return (DOMAINSET_ISSET(child->ds_prefer, &parent->ds_mask));
   }
   
   /*
    * Lookup or create a domainset.  The key is provided in ds_mask and
    * ds_policy.  If the domainset does not yet exist the storage in
    * 'domain' is used to insert.  Otherwise this storage is freed to the
    * domainset_zone and the existing domainset is returned.
    */
   static struct domainset *
   _domainset_create(struct domainset *domain, struct domainlist *freelist)
   {
           struct domainset *ndomain;
           int i, j;
   
           KASSERT(domain->ds_cnt <= vm_ndomains,
               ("invalid domain count in domainset %p", domain));
           KASSERT(domain->ds_policy != DOMAINSET_POLICY_PREFER ||
               domain->ds_prefer < vm_ndomains,
               ("invalid preferred domain in domains %p", domain));
   
           mtx_lock_spin(&cpuset_lock);
           LIST_FOREACH(ndomain, &cpuset_domains, ds_link)
                   if (domainset_equal(ndomain, domain))
                           break;
           /*
            * If the domain does not yet exist we insert it and initialize
            * various iteration helpers which are not part of the key.
            */
           if (ndomain == NULL) {
                   LIST_INSERT_HEAD(&cpuset_domains, domain, ds_link);
                   domain->ds_cnt = DOMAINSET_COUNT(&domain->ds_mask);
                   for (i = 0, j = 0; i < DOMAINSET_FLS(&domain->ds_mask); i++)
                           if (DOMAINSET_ISSET(i, &domain->ds_mask))
                                   domain->ds_order[j++] = i;
           }
           mtx_unlock_spin(&cpuset_lock);
           if (ndomain == NULL)
                   return (domain);
           if (freelist != NULL)
                   LIST_INSERT_HEAD(freelist, domain, ds_link);
           else
                   uma_zfree(domainset_zone, domain);
           return (ndomain);
   
   }
   
   /*
    * Are any of the domains in the mask empty?  If so, silently
    * remove them and update the domainset accordingly.  If only empty
    * domains are present, we must return failure.
    */
   static bool
   domainset_empty_vm(struct domainset *domain)
   {
           domainset_t empty;
           int i, j;
   
           DOMAINSET_ZERO(&empty);
           for (i = 0; i < vm_ndomains; i++)
                   if (VM_DOMAIN_EMPTY(i))
                           DOMAINSET_SET(i, &empty);
           if (DOMAINSET_SUBSET(&empty, &domain->ds_mask))
                   return (true);
   
           /* Remove empty domains from the set and recompute. */
           DOMAINSET_ANDNOT(&domain->ds_mask, &empty);
           domain->ds_cnt = DOMAINSET_COUNT(&domain->ds_mask);
           for (i = j = 0; i < DOMAINSET_FLS(&domain->ds_mask); i++)
                   if (DOMAINSET_ISSET(i, &domain->ds_mask))
                           domain->ds_order[j++] = i;
   
           /* Convert a PREFER policy referencing an empty domain to RR. */
           if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
               DOMAINSET_ISSET(domain->ds_prefer, &empty)) {
                   domain->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
                   domain->ds_prefer = -1;
           }
   
           return (false);
   }
   
   /*
    * Create or lookup a domainset based on the key held in 'domain'.
    */
   struct domainset *
   domainset_create(const struct domainset *domain)
   {
           struct domainset *ndomain;
   
           /*
            * Validate the policy.  It must specify a useable policy number with
            * only valid domains.  Preferred must include the preferred domain
            * in the mask.
            */
           if (domain->ds_policy <= DOMAINSET_POLICY_INVALID ||
               domain->ds_policy > DOMAINSET_POLICY_MAX)
                   return (NULL);
           if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
               !DOMAINSET_ISSET(domain->ds_prefer, &domain->ds_mask))
                   return (NULL);
           if (!DOMAINSET_SUBSET(&domainset0.ds_mask, &domain->ds_mask))
                   return (NULL);
           ndomain = uma_zalloc(domainset_zone, M_WAITOK | M_ZERO);
           domainset_copy(domain, ndomain);
           return _domainset_create(ndomain, NULL);
   }
   
   /*
    * Update thread domainset pointers.
    */
   static void
   domainset_notify(void)
   {
           struct thread *td;
           struct proc *p;
   
           sx_slock(&allproc_lock);
           FOREACH_PROC_IN_SYSTEM(p) {
                   PROC_LOCK(p);
                   if (p->p_state == PRS_NEW) {
                           PROC_UNLOCK(p);
                           continue;
                   }
                   FOREACH_THREAD_IN_PROC(p, td) {
                           thread_lock(td);
                           td->td_domain.dr_policy = td->td_cpuset->cs_domain;
                           thread_unlock(td);
                   }
                   PROC_UNLOCK(p);
           }
           sx_sunlock(&allproc_lock);
           kernel_object->domain.dr_policy = cpuset_kernel->cs_domain;
   }
   
   /*
    * Create a new set that is a subset of a parent.
    */
   static struct domainset *
   domainset_shadow(const struct domainset *pdomain,
       const struct domainset *domain, struct domainlist *freelist)
   {
           struct domainset *ndomain;
   
           ndomain = LIST_FIRST(freelist);
           LIST_REMOVE(ndomain, ds_link);
   
           /*
            * Initialize the key from the request.
            */
           domainset_copy(domain, ndomain);
   
           /*
            * Restrict the key by the parent.
            */
           DOMAINSET_AND(&ndomain->ds_mask, &pdomain->ds_mask);
   
           return _domainset_create(ndomain, freelist);
   }
   
   /*
    * Recursively check for errors that would occur from applying mask to
    * the tree of sets starting at 'set'.  Checks for sets that would become
    * empty as well as RDONLY flags.
    */
   static int
   cpuset_testupdate(struct cpuset *set, cpuset_t *mask, int augment_mask)
   {
           struct cpuset *nset;
           cpuset_t newmask;
           int error;
   
           mtx_assert(&cpuset_lock, MA_OWNED);
           if (set->cs_flags & CPU_SET_RDONLY)
                   return (EPERM);
           if (augment_mask) {
                   CPU_COPY(&set->cs_mask, &newmask);
                   CPU_AND(&newmask, mask);
           } else
                   CPU_COPY(mask, &newmask);
   
           if (CPU_EMPTY(&newmask))
                   return (EDEADLK);
           error = 0;
           LIST_FOREACH(nset, &set->cs_children, cs_siblings) 
                   if ((error = cpuset_testupdate(nset, &newmask, 1)) != 0)
                           break;
           return (error);
   }
   
   /*
    * Applies the mask 'mask' without checking for empty sets or permissions.
    */
   static void
   cpuset_update(struct cpuset *set, cpuset_t *mask)
   {
           struct cpuset *nset;
   
           mtx_assert(&cpuset_lock, MA_OWNED);
           CPU_AND(&set->cs_mask, mask);
           LIST_FOREACH(nset, &set->cs_children, cs_siblings) 
                   cpuset_update(nset, &set->cs_mask);
   
           return;
   }
   
   /*
    * Modify the set 'set' to use a copy of the mask provided.  Apply this new
    * mask to restrict all children in the tree.  Checks for validity before
    * applying the changes.
    */
   static int
   cpuset_modify(struct cpuset *set, cpuset_t *mask)
   {
           struct cpuset *root;
           int error;
   
           error = priv_check(curthread, PRIV_SCHED_CPUSET);
           if (error)
                   return (error);
           /*
            * In case we are called from within the jail,
            * we do not allow modifying the dedicated root
            * cpuset of the jail but may still allow to
            * change child sets, including subordinate jails'
            * roots.
            */
           if ((set->cs_flags & CPU_SET_ROOT) != 0 &&
               jailed(curthread->td_ucred) &&
               set == curthread->td_ucred->cr_prison->pr_cpuset)
                   return (EPERM);
           /*
            * Verify that we have access to this set of
            * cpus.
            */
           if ((set->cs_flags & (CPU_SET_ROOT | CPU_SET_RDONLY)) == CPU_SET_ROOT) {
                   KASSERT(set->cs_parent != NULL,
                       ("jail.cpuset=%d is not a proper child of parent jail's root.",
                       set->cs_id));
   
                   /*
                    * cpuset_getroot() cannot work here due to how top-level jail
                    * roots are constructed.  Top-level jails are parented to
                    * thread0's cpuset (i.e. cpuset 1) rather than the system root.
                    */
                   root = set->cs_parent;
           } else {
                   root = cpuset_getroot(set);
           }
           mtx_lock_spin(&cpuset_lock);
           if (root && !CPU_SUBSET(&root->cs_mask, mask)) {
                   error = EINVAL;
                   goto out;
           }
           error = cpuset_testupdate(set, mask, 0);
           if (error)
                   goto out;
           CPU_COPY(mask, &set->cs_mask);
           cpuset_update(set, mask);
   out:
           mtx_unlock_spin(&cpuset_lock);
   
           return (error);
   }
   
   /*
    * Recursively check for errors that would occur from applying mask to
    * the tree of sets starting at 'set'.  Checks for sets that would become
    * empty as well as RDONLY flags.
    */
   static int
   cpuset_testupdate_domain(struct cpuset *set, struct domainset *dset,
       struct domainset *orig, int *count, int augment_mask __unused)
   {
           struct cpuset *nset;
           struct domainset *domain;
           struct domainset newset;
           int error;
   
           mtx_assert(&cpuset_lock, MA_OWNED);
           if (set->cs_flags & CPU_SET_RDONLY)
                   return (EPERM);
           domain = set->cs_domain;
           domainset_copy(domain, &newset);
           if (!domainset_equal(domain, orig)) {
                   if (!domainset_restrict(domain, dset))
                           return (EDEADLK);
                   DOMAINSET_AND(&newset.ds_mask, &dset->ds_mask);
                   /* Count the number of domains that are changing. */
                   (*count)++;
           }
           error = 0;
           LIST_FOREACH(nset, &set->cs_children, cs_siblings) 
                   if ((error = cpuset_testupdate_domain(nset, &newset, domain,
                       count, 1)) != 0)
                           break;
           return (error);
   }
   
   /*
    * Applies the mask 'mask' without checking for empty sets or permissions.
    */
   static void
   cpuset_update_domain(struct cpuset *set, struct domainset *domain,
       struct domainset *orig, struct domainlist *domains)
   {
           struct cpuset *nset;
   
           mtx_assert(&cpuset_lock, MA_OWNED);
           /*
            * If this domainset has changed from the parent we must calculate
            * a new set.  Otherwise it simply inherits from the parent.  When
            * we inherit from the parent we get a new mask and policy.  If the
            * set is modified from the parent we keep the policy and only
            * update the mask.
            */
           if (set->cs_domain != orig) {
                   orig = set->cs_domain;
                   set->cs_domain = domainset_shadow(domain, orig, domains);
           } else
                   set->cs_domain = domain;
           LIST_FOREACH(nset, &set->cs_children, cs_siblings) 
                   cpuset_update_domain(nset, set->cs_domain, orig, domains);
   
           return;
   }
   
   /*
    * Modify the set 'set' to use a copy the domainset provided.  Apply this new
    * mask to restrict all children in the tree.  Checks for validity before
    * applying the changes.
    */
   static int
   cpuset_modify_domain(struct cpuset *set, struct domainset *domain)
   {
           struct domainlist domains;
           struct domainset temp;
           struct domainset *dset;
           struct cpuset *root;
           int ndomains, needed;
           int error;
   
           error = priv_check(curthread, PRIV_SCHED_CPUSET);
           if (error)
                   return (error);
           /*
            * In case we are called from within the jail
            * we do not allow modifying the dedicated root
            * cpuset of the jail but may still allow to
            * change child sets.
            */
           if (jailed(curthread->td_ucred) &&
               set->cs_flags & CPU_SET_ROOT)
                   return (EPERM);
           domainset_freelist_init(&domains, 0);
           domain = domainset_create(domain);
           ndomains = 0;
   
           mtx_lock_spin(&cpuset_lock);
           for (;;) {
                   root = cpuset_getroot(set);
                   dset = root->cs_domain;
                   /*
                    * Verify that we have access to this set of domains.
                    */
                   if (!domainset_valid(dset, domain)) {
                           error = EINVAL;
                           goto out;
                   }
                   /*
                    * If applying prefer we keep the current set as the fallback.
                    */
                   if (domain->ds_policy == DOMAINSET_POLICY_PREFER)
                           DOMAINSET_COPY(&set->cs_domain->ds_mask,
                               &domain->ds_mask);
                   /*
                    * Determine whether we can apply this set of domains and
                    * how many new domain structures it will require.
                    */
                   domainset_copy(domain, &temp);
                   needed = 0;
                   error = cpuset_testupdate_domain(set, &temp, set->cs_domain,
                       &needed, 0);
                   if (error)
                           goto out;
                   if (ndomains >= needed)
                           break;
   
                   /* Dropping the lock; we'll need to re-evaluate again. */
                   mtx_unlock_spin(&cpuset_lock);
                   domainset_freelist_add(&domains, needed - ndomains);
                   ndomains = needed;
                   mtx_lock_spin(&cpuset_lock);
           }
           dset = set->cs_domain;
           cpuset_update_domain(set, domain, dset, &domains);
   out:
           mtx_unlock_spin(&cpuset_lock);
           domainset_freelist_free(&domains);
           if (error == 0)
                   domainset_notify();
   
           return (error);
   }
   
   /*
    * Resolve the 'which' parameter of several cpuset apis.
    *
    * For WHICH_PID and WHICH_TID return a locked proc and valid proc/tid.  Also
    * checks for permission via p_cansched().
    *
    * For WHICH_SET returns a valid set with a new reference.
    *
    * -1 may be supplied for any argument to mean the current proc/thread or
    * the base set of the current thread.  May fail with ESRCH/EPERM.
    */
   int
   cpuset_which(cpuwhich_t which, id_t id, struct proc **pp, struct thread **tdp,
       struct cpuset **setp)
   {
           struct cpuset *set;
           struct thread *td;
           struct proc *p;
           int error;
   
           *pp = p = NULL;
           *tdp = td = NULL;
           *setp = set = NULL;
           switch (which) {
           case CPU_WHICH_PID:
                   if (id == -1) {
                           PROC_LOCK(curproc);
                           p = curproc;
                           break;
                   }
                   if ((p = pfind(id)) == NULL)
                           return (ESRCH);
                   break;
           case CPU_WHICH_TID:
                   if (id == -1) {
                           PROC_LOCK(curproc);
                           p = curproc;
                           td = curthread;
                           break;
                   }
                   td = tdfind(id, -1);
                   if (td == NULL)
                           return (ESRCH);
                   p = td->td_proc;
                   break;
           case CPU_WHICH_CPUSET:
                   if (id == -1) {
                           thread_lock(curthread);
                           set = cpuset_refbase(curthread->td_cpuset);
                           thread_unlock(curthread);
                   } else
                           set = cpuset_lookup(id, curthread);
                   if (set) {
                           *setp = set;
                           return (0);
                   }
                   return (ESRCH);
           case CPU_WHICH_JAIL:
           {
                   /* Find `set' for prison with given id. */
                   struct prison *pr;
   
                   sx_slock(&allprison_lock);
                   pr = prison_find_child(curthread->td_ucred->cr_prison, id);
                   sx_sunlock(&allprison_lock);
                   if (pr == NULL)
                           return (ESRCH);
                   cpuset_ref(pr->pr_cpuset);
                   *setp = pr->pr_cpuset;
                   mtx_unlock(&pr->pr_mtx);
                   return (0);
           }
           case CPU_WHICH_IRQ:
           case CPU_WHICH_DOMAIN:
                   return (0);
           default:
                   return (EINVAL);
           }
           error = p_cansched(curthread, p);
           if (error) {
                   PROC_UNLOCK(p);
                   return (error);
           }
           if (td == NULL)
                   td = FIRST_THREAD_IN_PROC(p);
           *pp = p;
           *tdp = td;
           return (0);
   }
   
   static int
   cpuset_testshadow(struct cpuset *set, const cpuset_t *mask,
       const struct domainset *domain)
   {
           struct cpuset *parent;
           struct domainset *dset;
   
           parent = cpuset_getbase(set);
           /*
            * If we are restricting a cpu mask it must be a subset of the
            * parent or invalid CPUs have been specified.
            */
           if (mask != NULL && !CPU_SUBSET(&parent->cs_mask, mask))
                   return (EINVAL);
   
           /*
            * If we are restricting a domain mask it must be a subset of the
            * parent or invalid domains have been specified.
            */
           dset = parent->cs_domain;
           if (domain != NULL && !domainset_valid(dset, domain))
                   return (EINVAL);
   
           return (0);
   }
   
   /*
    * Create an anonymous set with the provided mask in the space provided by
    * 'nset'.  If the passed in set is anonymous we use its parent otherwise
    * the new set is a child of 'set'.
    */
   static int
   cpuset_shadow(struct cpuset *set, struct cpuset **nsetp,
      const cpuset_t *mask, const struct domainset *domain,
      struct setlist *cpusets, struct domainlist *domains)
  {
          struct cpuset *parent;
          struct cpuset *nset;
          struct domainset *dset;
          struct domainset *d;
          int error;
  
          error = cpuset_testshadow(set, mask, domain);
          if (error)
                  return (error);
  
          parent = cpuset_getbase(set);
          dset = parent->cs_domain;
          if (mask == NULL)
                  mask = &set->cs_mask;
          if (domain != NULL)
                  d = domainset_shadow(dset, domain, domains);
          else
                  d = set->cs_domain;
          nset = LIST_FIRST(cpusets);
          error = cpuset_init(nset, parent, mask, d, CPUSET_INVALID);
          if (error == 0) {
                  LIST_REMOVE(nset, cs_link);
                  *nsetp = nset;
          }
          return (error);
  }
  
  static struct cpuset *
  cpuset_update_thread(struct thread *td, struct cpuset *nset)
  {
          struct cpuset *tdset;
  
          tdset = td->td_cpuset;
          td->td_cpuset = nset;
          td->td_domain.dr_policy = nset->cs_domain;
          sched_affinity(td);
  
          return (tdset);
  }
  
  static int
  cpuset_setproc_test_maskthread(struct cpuset *tdset, cpuset_t *mask,
      struct domainset *domain)
  {
          struct cpuset *parent;
  
          parent = cpuset_getbase(tdset);
          if (mask == NULL)
                  mask = &tdset->cs_mask;
          if (domain == NULL)
                  domain = tdset->cs_domain;
          return cpuset_testshadow(parent, mask, domain);
  }
  
  static int
  cpuset_setproc_maskthread(struct cpuset *tdset, cpuset_t *mask,
      struct domainset *domain, struct cpuset **nsetp,
      struct setlist *freelist, struct domainlist *domainlist)
  {
          struct cpuset *parent;
  
          parent = cpuset_getbase(tdset);
          if (mask == NULL)
                  mask = &tdset->cs_mask;
          if (domain == NULL)
                  domain = tdset->cs_domain;
          return cpuset_shadow(parent, nsetp, mask, domain, freelist,
              domainlist);
  }
  
  static int
  cpuset_setproc_setthread_mask(struct cpuset *tdset, struct cpuset *set,
      cpuset_t *mask, struct domainset *domain)
  {
          struct cpuset *parent;
  
          parent = cpuset_getbase(tdset);
  
          /*
           * If the thread restricted its mask then apply that same
           * restriction to the new set, otherwise take it wholesale.
           */
          if (CPU_CMP(&tdset->cs_mask, &parent->cs_mask) != 0) {
                  CPU_COPY(&tdset->cs_mask, mask);
                  CPU_AND(mask, &set->cs_mask);
          } else
                  CPU_COPY(&set->cs_mask, mask);
  
          /*
           * If the thread restricted the domain then we apply the
           * restriction to the new set but retain the policy.
           */
          if (tdset->cs_domain != parent->cs_domain) {
                  domainset_copy(tdset->cs_domain, domain);
                  DOMAINSET_AND(&domain->ds_mask, &set->cs_domain->ds_mask);
          } else
                  domainset_copy(set->cs_domain, domain);
  
          if (CPU_EMPTY(mask) || DOMAINSET_EMPTY(&domain->ds_mask))
                  return (EDEADLK);
  
          return (0);
  }
  
  static int
  cpuset_setproc_test_setthread(struct cpuset *tdset, struct cpuset *set)
  {
          struct domainset domain;
          cpuset_t mask;
  
          if (tdset->cs_id != CPUSET_INVALID)
                  return (0);
          return cpuset_setproc_setthread_mask(tdset, set, &mask, &domain);
  }
  
  static int
  cpuset_setproc_setthread(struct cpuset *tdset, struct cpuset *set,
      struct cpuset **nsetp, struct setlist *freelist,
      struct domainlist *domainlist)
  {
          struct domainset domain;
          cpuset_t mask;
          int error;
  
          /*
           * If we're replacing on a thread that has not constrained the
           * original set we can simply accept the new set.
           */
          if (tdset->cs_id != CPUSET_INVALID) {
                  *nsetp = cpuset_ref(set);
                  return (0);
          }
          error = cpuset_setproc_setthread_mask(tdset, set, &mask, &domain);
          if (error)
                  return (error);
  
          return cpuset_shadow(set, nsetp, &mask, &domain, freelist,
              domainlist);
  }
  
  static int
  cpuset_setproc_newbase(struct thread *td, struct cpuset *set,
      struct cpuset *nroot, struct cpuset **nsetp,
      struct setlist *cpusets, struct domainlist *domainlist)
  {
          struct domainset ndomain;
          cpuset_t nmask;
          struct cpuset *pbase;
          int error;
  
          pbase = cpuset_getbase(td->td_cpuset);
  
          /* Copy process mask, then further apply the new root mask. */
          CPU_COPY(&pbase->cs_mask, &nmask);
          CPU_AND(&nmask, &nroot->cs_mask);
  
          domainset_copy(pbase->cs_domain, &ndomain);
          DOMAINSET_AND(&ndomain.ds_mask, &set->cs_domain->ds_mask);
  
          /* Policy is too restrictive, will not work. */
          if (CPU_EMPTY(&nmask) || DOMAINSET_EMPTY(&ndomain.ds_mask))
                  return (EDEADLK);
  
          /*
           * Remove pbase from the freelist in advance, it'll be pushed to
           * cpuset_ids on success.  We assume here that cpuset_create() will not
           * touch pbase on failure, and we just enqueue it back to the freelist
           * to remain in a consistent state.
           */
          pbase = LIST_FIRST(cpusets);
          LIST_REMOVE(pbase, cs_link);
          error = cpuset_create(&pbase, set, &nmask);
          if (error != 0) {
                  LIST_INSERT_HEAD(cpusets, pbase, cs_link);
                  return (error);
          }
  
          /* Duplicates some work from above... oh well. */
          pbase->cs_domain = domainset_shadow(set->cs_domain, &ndomain,
              domainlist);
          *nsetp = pbase;
          return (0);
  }
  
  /*
   * 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 base set,
   *    then reparents all anonymous sets either to that set or the provided set
   *    if one was not created.  Non-anonymous sets are similarly replaced.
   * 3) Mask is non-null.  This replaces or creates anonymous sets for every
   *    thread with the existing base as a parent.
   * 4) domain is non-null.  This creates anonymous sets for every thread
   *    and replaces the domain set.
   *
   * This is overly complicated because we can't allocate while holding a 
   * spinlock and spinlocks must be held while changing and examining thread
   * 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
           * rejected with EDEADLK.
           */
          if (set != NULL && rebase && nroot != tdroot) {
                  cpusetid_t base_id, root_id;
  
                  root_id = td->td_ucred->cr_prison->pr_cpuset->cs_id;
                  base_id = cpuset_getbase(td->td_cpuset)->cs_id;
  
                  if (base_id != root_id) {
                          error = cpuset_setproc_newbase(td, set, nroot, &base,
                              &freelist, &domainlist);
                          if (error == EDEADLK &&
                              priv_check(td, PRIV_SCHED_CPUSET) == 0)
                                  error = 0;
                          if (error != 0)
                                  goto unlock_out;
                  }
          }
  
          /*
           * Now that the appropriate locks are held and we have enough cpusets,
           * make sure the operation will succeed before applying changes. The
           * proc lock prevents td_cpuset from changing between calls.
           */
          error = 0;
          FOREACH_THREAD_IN_PROC(p, td) {
                  thread_lock(td);
                  if (set != NULL)
                          error = cpuset_setproc_test_setthread(td->td_cpuset,
                              base);
                  else
                          error = cpuset_setproc_test_maskthread(td->td_cpuset,
                              mask, domain);
                  thread_unlock(td);
                  if (error)
                          goto unlock_out;
          }
          /*
           * Replace each thread's cpuset while using deferred release.  We
           * must do this because the thread lock must be held while operating
           * on the thread and this limits the type of operations allowed.
           */
          FOREACH_THREAD_IN_PROC(p, td) {
                  thread_lock(td);
                  if (set != NULL)
                          error = cpuset_setproc_setthread(td->td_cpuset, base,
                              &nset, &freelist, &domainlist);
                  else
                          error = cpuset_setproc_maskthread(td->td_cpuset, mask,
                              domain, &nset, &freelist, &domainlist);
                  if (error) {
                          thread_unlock(td);
                          break;
                  }
                  cpuset_rel_defer(&droplist, cpuset_update_thread(td, nset));
                  thread_unlock(td);
          }
  unlock_out:
          PROC_UNLOCK(p);
  out:
          if (base != NULL && base != set)
                  cpuset_rel(base);
          while ((nset = LIST_FIRST(&droplist)) != NULL)
                  cpuset_rel_complete(nset);
          cpuset_freelist_free(&freelist);
          domainset_freelist_free(&domainlist);
          return (error);
  }
  
  static int
  bitset_strprint(char *buf, size_t bufsiz, const struct bitset *set, int setlen)
  {
          size_t bytes;
          int i, once;
          char *p;
  
          once = 0;
          p = buf;
          for (i = 0; i < __bitset_words(setlen); i++) {
                  if (once != 0) {
                          if (bufsiz < 1)
                                  return (0);
                          *p = ',';
                          p++;
                          bufsiz--;
                  } else
                          once = 1;
                  if (bufsiz < sizeof(__STRING(ULONG_MAX)))
                          return (0);
                  bytes = snprintf(p, bufsiz, "%lx", set->__bits[i]);
                  p += bytes;
                  bufsiz -= bytes;
          }
          return (p - buf);
  }
  
  static int
  bitset_strscan(struct bitset *set, int setlen, const char *buf)
  {
          int i, ret;
          const char *p;
  
          BIT_ZERO(setlen, set);
          p = buf;
          for (i = 0; i < __bitset_words(setlen); i++) {
                  if (*p == ',') {
                          p++;
                          continue;
                  }
                  ret = sscanf(p, "%lx", &set->__bits[i]);
                  if (ret == 0 || ret == -1)
                          break;
                  while (isxdigit(*p))
                          p++;
          }
          return (p - buf);
  }
  
  /*
   * Return a string representing a valid layout for a cpuset_t object.
   * It expects an incoming buffer at least sized as CPUSETBUFSIZ.
   */
  char *
  cpusetobj_strprint(char *buf, const cpuset_t *set)
  {
  
          bitset_strprint(buf, CPUSETBUFSIZ, (const struct bitset *)set,
              CPU_SETSIZE);
          return (buf);
  }
  
  /*
   * Build a valid cpuset_t object from a string representation.
   * It expects an incoming buffer at least sized as CPUSETBUFSIZ.
   */
  int
  cpusetobj_strscan(cpuset_t *set, const char *buf)
  {
          char p;
  
          if (strlen(buf) > CPUSETBUFSIZ - 1)
                  return (-1);
  
          p = buf[bitset_strscan((struct bitset *)set, CPU_SETSIZE, buf)];
          if (p != '\0')
                  return (-1);
  
          return (0);
  }
  
  /*
   * Handle a domainset specifier in the sysctl tree.  A poiner to a pointer to
   * a domainset is in arg1.  If the user specifies a valid domainset the
   * pointer is updated.
   *
   * Format is:
   * hex mask word 0,hex mask word 1,...:decimal policy:decimal preferred
   */
  int
  sysctl_handle_domainset(SYSCTL_HANDLER_ARGS)
  {
          char buf[DOMAINSETBUFSIZ];
          struct domainset *dset;
          struct domainset key;
          int policy, prefer, error;
          char *p;
  
          dset = *(struct domainset **)arg1;
          error = 0;
  
          if (dset != NULL) {
                  p = buf + bitset_strprint(buf, DOMAINSETBUFSIZ,
                      (const struct bitset *)&dset->ds_mask, DOMAINSET_SETSIZE);
                  sprintf(p, ":%d:%d", dset->ds_policy, dset->ds_prefer);
          } else
                  sprintf(buf, "<NULL>");
          error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
          if (error != 0 || req->newptr == NULL)
                  return (error);
  
          /*
           * Read in and validate the string.
           */
          memset(&key, 0, sizeof(key));
          p = &buf[bitset_strscan((struct bitset *)&key.ds_mask,
              DOMAINSET_SETSIZE, buf)];
          if (p == buf)
                  return (EINVAL);
          if (sscanf(p, ":%d:%d", &policy, &prefer) != 2)
                  return (EINVAL);
          key.ds_policy = policy;
          key.ds_prefer = prefer;
  
          /* Domainset_create() validates the policy.*/
          dset = domainset_create(&key);
          if (dset == NULL)
                  return (EINVAL);
          *(struct domainset **)arg1 = dset;
  
          return (error);
  }
  
  /*
   * Apply an anonymous mask or a domain to a single thread.
   */
  static int
  _cpuset_setthread(lwpid_t id, cpuset_t *mask, struct domainset *domain)
  {
          struct setlist cpusets;
          struct domainlist domainlist;
          struct cpuset *nset;
          struct cpuset *set;
          struct thread *td;
          struct proc *p;
          int error;
  
          cpuset_freelist_init(&cpusets, 1);
          domainset_freelist_init(&domainlist, domain != NULL);
          error = cpuset_which(CPU_WHICH_TID, id, &p, &td, &set);
          if (error)
                  goto out;
          set = NULL;
          thread_lock(td);
          error = cpuset_shadow(td->td_cpuset, &nset, mask, domain,
              &cpusets, &domainlist);
          if (error == 0)
                  set = cpuset_update_thread(td, nset);
          thread_unlock(td);
          PROC_UNLOCK(p);
          if (set)
                  cpuset_rel(set);
  out:
          cpuset_freelist_free(&cpusets);
          domainset_freelist_free(&domainlist);
          return (error);
  }
  
  /*
   * Apply an anonymous mask to a single thread.
   */
  int
  cpuset_setthread(lwpid_t id, cpuset_t *mask)
  {
  
          return _cpuset_setthread(id, mask, NULL);
  }
  
  /*
   * Apply new cpumask to the ithread.
   */
  int
  cpuset_setithread(lwpid_t id, int cpu)
  {
          cpuset_t mask;
  
          CPU_ZERO(&mask);
          if (cpu == NOCPU)
                  CPU_COPY(cpuset_root, &mask);
          else
                  CPU_SET(cpu, &mask);
          return _cpuset_setthread(id, &mask, NULL);
  }
  
  /*
   * Initialize static domainsets after NUMA information is available.  This is
   * called before memory allocators are initialized.
   */
  void
  domainset_init(void)
  {
          struct domainset *dset;
          int i;
  
          dset = &domainset_roundrobin;
          DOMAINSET_COPY(&all_domains, &dset->ds_mask);
          dset->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
          dset->ds_prefer = -1;
          _domainset_create(dset, NULL);
  
          for (i = 0; i < vm_ndomains; i++) {
                  dset = &domainset_fixed[i];
                  DOMAINSET_ZERO(&dset->ds_mask);
                  DOMAINSET_SET(i, &dset->ds_mask);
                  dset->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
                  _domainset_create(dset, NULL);
  
                  dset = &domainset_prefer[i];
                  DOMAINSET_COPY(&all_domains, &dset->ds_mask);
                  dset->ds_policy = DOMAINSET_POLICY_PREFER;
                  dset->ds_prefer = i;
                  _domainset_create(dset, NULL);
          }
  }
  
  /*
   * Create the domainset for cpuset 0, 1 and cpuset 2.
   */
  void
  domainset_zero(void)
  {
          struct domainset *dset, *tmp;
  
          mtx_init(&cpuset_lock, "cpuset", NULL, MTX_SPIN | MTX_RECURSE);
  
          dset = &domainset0;
          DOMAINSET_COPY(&all_domains, &dset->ds_mask);
          dset->ds_policy = DOMAINSET_POLICY_FIRSTTOUCH;
          dset->ds_prefer = -1;
          curthread->td_domain.dr_policy = _domainset_create(dset, NULL);
  
          domainset_copy(dset, &domainset2);
          domainset2.ds_policy = DOMAINSET_POLICY_INTERLEAVE;
          kernel_object->domain.dr_policy = _domainset_create(&domainset2, NULL);
  
          /* Remove empty domains from the global policies. */
          LIST_FOREACH_SAFE(dset, &cpuset_domains, ds_link, tmp)
                  if (domainset_empty_vm(dset))
                          LIST_REMOVE(dset, ds_link);
  }
  
  /*
   * Creates system-wide cpusets and the cpuset for thread0 including three
   * sets:
   * 
   * 0 - The root set which should represent all valid processors in the
   *     system.  This set is immutable.
   * 1 - The default set which all processes are a member of until changed.
   *     This allows an administrator to move all threads off of given cpus to
   *     dedicate them to high priority tasks or save power etc.
   * 2 - The kernel set which allows restriction and policy to be applied only
   *     to kernel threads and the kernel_object.
   */
  struct cpuset *
  cpuset_thread0(void)
  {
          struct cpuset *set;
          int i;
          int error __unused;
  
          cpuset_zone = uma_zcreate("cpuset", sizeof(struct cpuset), NULL, NULL,
              NULL, NULL, UMA_ALIGN_CACHE, 0);
          domainset_zone = uma_zcreate("domainset", sizeof(struct domainset),
              NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0);
  
          /*
           * Create the root system set (0) for the whole machine.  Doesn't use
           * cpuset_create() due to NULL parent.
           */
          set = uma_zalloc(cpuset_zone, M_WAITOK | M_ZERO);
          CPU_COPY(&all_cpus, &set->cs_mask);
          LIST_INIT(&set->cs_children);
          LIST_INSERT_HEAD(&cpuset_ids, set, cs_link);
          refcount_init(&set->cs_ref, 1);
          set->cs_flags = CPU_SET_ROOT | CPU_SET_RDONLY;
          set->cs_domain = &domainset0;
          cpuset_zero = set;
          cpuset_root = &set->cs_mask;
  
          /*
           * Now derive a default (1), modifiable set from that to give out.
           */
          set = uma_zalloc(cpuset_zone, M_WAITOK | M_ZERO);
          error = cpuset_init(set, cpuset_zero, NULL, NULL, 1);
          KASSERT(error == 0, ("Error creating default set: %d\n", error));
          cpuset_default = set;
          /*
           * Create the kernel set (2).
           */
          set = uma_zalloc(cpuset_zone, M_WAITOK | M_ZERO);
          error = cpuset_init(set, cpuset_zero, NULL, NULL, 2);
          KASSERT(error == 0, ("Error creating kernel set: %d\n", error));
          set->cs_domain = &domainset2;
          cpuset_kernel = set;
  
          /*
           * Initialize the unit allocator. 0 and 1 are allocated above.
           */
          cpuset_unr = new_unrhdr(3, INT_MAX, NULL);
  
          /*
           * If MD code has not initialized per-domain cpusets, place all
           * CPUs in domain 0.
           */
          for (i = 0; i < MAXMEMDOM; i++)
                  if (!CPU_EMPTY(&cpuset_domain[i]))
                          goto domains_set;
          CPU_COPY(&all_cpus, &cpuset_domain[0]);
  domains_set:
  
          return (cpuset_default);
  }
  
  void
  cpuset_kernthread(struct thread *td)
  {
          struct cpuset *set;
  
          thread_lock(td);
          set = td->td_cpuset;
          td->td_cpuset = cpuset_ref(cpuset_kernel);
          thread_unlock(td);
          cpuset_rel(set);
  }
  
  /*
   * Create a cpuset, which would be cpuset_create() but
   * mark the new 'set' as root.
   *
   * We are not going to reparent the td to it.  Use cpuset_setproc_update_set()
   * for that.
   *
   * In case of no error, returns the set in *setp locked with a reference.
   */
  int
  cpuset_create_root(struct prison *pr, struct cpuset **setp)
  {
          struct cpuset *set;
          int error;
  
          KASSERT(pr != NULL, ("[%s:%d] invalid pr", __func__, __LINE__));
          KASSERT(setp != NULL, ("[%s:%d] invalid setp", __func__, __LINE__));
  
          set = NULL;
          error = cpuset_create(&set, pr->pr_cpuset, &pr->pr_cpuset->cs_mask);
          if (error)
                  return (error);
  
          KASSERT(set != NULL, ("[%s:%d] cpuset_create returned invalid data",
              __func__, __LINE__));
  
          /* Mark the set as root. */
          set->cs_flags |= CPU_SET_ROOT;
          *setp = set;
  
          return (0);
  }
  
  int
  cpuset_setproc_update_set(struct proc *p, struct cpuset *set)
  {
          int error;
  
          KASSERT(p != NULL, ("[%s:%d] invalid proc", __func__, __LINE__));
          KASSERT(set != NULL, ("[%s:%d] invalid set", __func__, __LINE__));
  
          cpuset_ref(set);
          error = cpuset_setproc(p->p_pid, set, NULL, NULL, true);
          if (error)
                  return (error);
          cpuset_rel(set);
          return (0);
  }
  
  /*
   * In Capability mode, the only accesses that are permitted are to the current
   * thread and process' CPU and domain sets.
   */
  static int
  cpuset_check_capabilities(struct thread *td, cpulevel_t level, cpuwhich_t which,
      id_t id)
  {
          if (IN_CAPABILITY_MODE(td)) {
                  if (level != CPU_LEVEL_WHICH)
                          return (ECAPMODE);
                  if (which != CPU_WHICH_TID && which != CPU_WHICH_PID)
                          return (ECAPMODE);
                  if (id != -1 &&
                      !(which == CPU_WHICH_TID && id == td->td_tid) &&
                      !(which == CPU_WHICH_PID && id == td->td_proc->p_pid))
                          return (ECAPMODE);
          }
          return (0);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_args {
          cpusetid_t      *setid;
  };
  #endif
  int
  sys_cpuset(struct thread *td, struct cpuset_args *uap)
  {
          struct cpuset *root;
          struct cpuset *set;
          int error;
  
          thread_lock(td);
          root = cpuset_refroot(td->td_cpuset);
          thread_unlock(td);
          set = NULL;
          error = cpuset_create(&set, root, &root->cs_mask);
          cpuset_rel(root);
          if (error)
                  return (error);
          error = copyout(&set->cs_id, uap->setid, sizeof(set->cs_id));
          if (error == 0)
                  error = cpuset_setproc(-1, set, NULL, NULL, false);
          cpuset_rel(set);
          return (error);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_setid_args {
          cpuwhich_t      which;
          id_t            id;
          cpusetid_t      setid;
  };
  #endif
  int
  sys_cpuset_setid(struct thread *td, struct cpuset_setid_args *uap)
  {
  
          return (kern_cpuset_setid(td, uap->which, uap->id, uap->setid));
  }
  
  int
  kern_cpuset_setid(struct thread *td, cpuwhich_t which,
      id_t id, cpusetid_t setid)
  {
          struct cpuset *set;
          int error;
  
          /*
           * Presently we only support per-process sets.
           */
          if (which != CPU_WHICH_PID)
                  return (EINVAL);
          set = cpuset_lookup(setid, td);
          if (set == NULL)
                  return (ESRCH);
          error = cpuset_setproc(id, set, NULL, NULL, false);
          cpuset_rel(set);
          return (error);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_getid_args {
          cpulevel_t      level;
          cpuwhich_t      which;
          id_t            id;
          cpusetid_t      *setid;
  };
  #endif
  int
  sys_cpuset_getid(struct thread *td, struct cpuset_getid_args *uap)
  {
  
          return (kern_cpuset_getid(td, uap->level, uap->which, uap->id,
              uap->setid));
  }
  
  int
  kern_cpuset_getid(struct thread *td, cpulevel_t level, cpuwhich_t which,
      id_t id, cpusetid_t *setid)
  {
          struct cpuset *nset;
          struct cpuset *set;
          struct thread *ttd;
          struct proc *p;
          cpusetid_t tmpid;
          int error;
  
          if (level == CPU_LEVEL_WHICH && which != CPU_WHICH_CPUSET)
                  return (EINVAL);
          error = cpuset_which(which, id, &p, &ttd, &set);
          if (error)
                  return (error);
          switch (which) {
          case CPU_WHICH_TID:
          case CPU_WHICH_PID:
                  thread_lock(ttd);
                  set = cpuset_refbase(ttd->td_cpuset);
                  thread_unlock(ttd);
                  PROC_UNLOCK(p);
                  break;
          case CPU_WHICH_CPUSET:
          case CPU_WHICH_JAIL:
                  break;
          case CPU_WHICH_IRQ:
          case CPU_WHICH_DOMAIN:
                  return (EINVAL);
          }
          switch (level) {
          case CPU_LEVEL_ROOT:
                  nset = cpuset_refroot(set);
                  cpuset_rel(set);
                  set = nset;
                  break;
          case CPU_LEVEL_CPUSET:
                  break;
          case CPU_LEVEL_WHICH:
                  break;
          }
          tmpid = set->cs_id;
          cpuset_rel(set);
          if (error == 0)
                  error = copyout(&tmpid, setid, sizeof(tmpid));
  
          return (error);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_getaffinity_args {
          cpulevel_t      level;
          cpuwhich_t      which;
          id_t            id;
          size_t          cpusetsize;
          cpuset_t        *mask;
  };
  #endif
  int
  sys_cpuset_getaffinity(struct thread *td, struct cpuset_getaffinity_args *uap)
  {
  
          return (kern_cpuset_getaffinity(td, uap->level, uap->which,
              uap->id, uap->cpusetsize, uap->mask));
  }
  
  int
  kern_cpuset_getaffinity(struct thread *td, cpulevel_t level, cpuwhich_t which,
      id_t id, size_t cpusetsize, cpuset_t *maskp)
  {
          struct thread *ttd;
          struct cpuset *nset;
          struct cpuset *set;
          struct proc *p;
          cpuset_t *mask;
          int error;
          size_t size;
  
          if (cpusetsize < sizeof(cpuset_t) || cpusetsize > CPU_MAXSIZE / NBBY)
                  return (ERANGE);
          error = cpuset_check_capabilities(td, level, which, id);
          if (error != 0)
                  return (error);
          size = cpusetsize;
          mask = malloc(size, M_TEMP, M_WAITOK | M_ZERO);
          error = cpuset_which(which, id, &p, &ttd, &set);
          if (error)
                  goto out;
          switch (level) {
          case CPU_LEVEL_ROOT:
          case CPU_LEVEL_CPUSET:
                  switch (which) {
                  case CPU_WHICH_TID:
                  case CPU_WHICH_PID:
                          thread_lock(ttd);
                          set = cpuset_ref(ttd->td_cpuset);
                          thread_unlock(ttd);
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                  case CPU_WHICH_DOMAIN:
                          error = EINVAL;
                          goto out;
                  }
                  if (level == CPU_LEVEL_ROOT)
                          nset = cpuset_refroot(set);
                  else
                          nset = cpuset_refbase(set);
                  CPU_COPY(&nset->cs_mask, mask);
                  cpuset_rel(nset);
                  break;
          case CPU_LEVEL_WHICH:
                  switch (which) {
                  case CPU_WHICH_TID:
                          thread_lock(ttd);
                          CPU_COPY(&ttd->td_cpuset->cs_mask, mask);
                          thread_unlock(ttd);
                          break;
                  case CPU_WHICH_PID:
                          FOREACH_THREAD_IN_PROC(p, ttd) {
                                  thread_lock(ttd);
                                  CPU_OR(mask, &ttd->td_cpuset->cs_mask);
                                  thread_unlock(ttd);
                          }
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          CPU_COPY(&set->cs_mask, mask);
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                          error = intr_getaffinity(id, which, mask);
                          break;
                  case CPU_WHICH_DOMAIN:
                          if (id < 0 || id >= MAXMEMDOM)
                                  error = ESRCH;
                          else
                                  CPU_COPY(&cpuset_domain[id], mask);
                          break;
                  }
                  break;
          default:
                  error = EINVAL;
                  break;
          }
          if (set)
                  cpuset_rel(set);
          if (p)
                  PROC_UNLOCK(p);
          if (error == 0)
                  error = copyout(mask, maskp, size);
  out:
          free(mask, M_TEMP);
          return (error);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_setaffinity_args {
          cpulevel_t      level;
          cpuwhich_t      which;
          id_t            id;
          size_t          cpusetsize;
          const cpuset_t  *mask;
  };
  #endif
  int
  sys_cpuset_setaffinity(struct thread *td, struct cpuset_setaffinity_args *uap)
  {
  
          return (kern_cpuset_setaffinity(td, uap->level, uap->which,
              uap->id, uap->cpusetsize, uap->mask));
  }
  
  int
  kern_cpuset_setaffinity(struct thread *td, cpulevel_t level, cpuwhich_t which,
      id_t id, size_t cpusetsize, const cpuset_t *maskp)
  {
          struct cpuset *nset;
          struct cpuset *set;
          struct thread *ttd;
          struct proc *p;
          cpuset_t *mask;
          int error;
  
          if (cpusetsize < sizeof(cpuset_t) || cpusetsize > CPU_MAXSIZE / NBBY)
                  return (ERANGE);
          error = cpuset_check_capabilities(td, level, which, id);
          if (error != 0)
                  return (error);
          mask = malloc(cpusetsize, M_TEMP, M_WAITOK | M_ZERO);
          error = copyin(maskp, mask, cpusetsize);
          if (error)
                  goto out;
          /*
           * Verify that no high bits are set.
           */
          if (cpusetsize > sizeof(cpuset_t)) {
                  char *end;
                  char *cp;
  
                  end = cp = (char *)&mask->__bits;
                  end += cpusetsize;
                  cp += sizeof(cpuset_t);
                  while (cp != end)
                          if (*cp++ != 0) {
                                  error = EINVAL;
                                  goto out;
                          }
          }
          if (CPU_EMPTY(mask)) {
                  error = EDEADLK;
                  goto out;
          }
          switch (level) {
          case CPU_LEVEL_ROOT:
          case CPU_LEVEL_CPUSET:
                  error = cpuset_which(which, id, &p, &ttd, &set);
                  if (error)
                          break;
                  switch (which) {
                  case CPU_WHICH_TID:
                  case CPU_WHICH_PID:
                          thread_lock(ttd);
                          set = cpuset_ref(ttd->td_cpuset);
                          thread_unlock(ttd);
                          PROC_UNLOCK(p);
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                  case CPU_WHICH_DOMAIN:
                          error = EINVAL;
                          goto out;
                  }
                  if (level == CPU_LEVEL_ROOT)
                          nset = cpuset_refroot(set);
                  else
                          nset = cpuset_refbase(set);
                  error = cpuset_modify(nset, mask);
                  cpuset_rel(nset);
                  cpuset_rel(set);
                  break;
          case CPU_LEVEL_WHICH:
                  switch (which) {
                  case CPU_WHICH_TID:
                          error = cpuset_setthread(id, mask);
                          break;
                  case CPU_WHICH_PID:
                          error = cpuset_setproc(id, NULL, mask, NULL, false);
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          error = cpuset_which(which, id, &p, &ttd, &set);
                          if (error == 0) {
                                  error = cpuset_modify(set, mask);
                                  cpuset_rel(set);
                          }
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                          error = intr_setaffinity(id, which, mask);
                          break;
                  default:
                          error = EINVAL;
                          break;
                  }
                  break;
          default:
                  error = EINVAL;
                  break;
          }
  out:
          free(mask, M_TEMP);
          return (error);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_getdomain_args {
          cpulevel_t      level;
          cpuwhich_t      which;
          id_t            id;
          size_t          domainsetsize;
          domainset_t     *mask;
          int             *policy;
  };
  #endif
  int
  sys_cpuset_getdomain(struct thread *td, struct cpuset_getdomain_args *uap)
  {
  
          return (kern_cpuset_getdomain(td, uap->level, uap->which,
              uap->id, uap->domainsetsize, uap->mask, uap->policy));
  }
  
  int
  kern_cpuset_getdomain(struct thread *td, cpulevel_t level, cpuwhich_t which,
      id_t id, size_t domainsetsize, domainset_t *maskp, int *policyp)
  {
          struct domainset outset;
          struct thread *ttd;
          struct cpuset *nset;
          struct cpuset *set;
          struct domainset *dset;
          struct proc *p;
          domainset_t *mask;
          int error;
  
          if (domainsetsize < sizeof(domainset_t) ||
              domainsetsize > DOMAINSET_MAXSIZE / NBBY)
                  return (ERANGE);
          error = cpuset_check_capabilities(td, level, which, id);
          if (error != 0)
                  return (error);
          mask = malloc(domainsetsize, M_TEMP, M_WAITOK | M_ZERO);
          bzero(&outset, sizeof(outset));
          error = cpuset_which(which, id, &p, &ttd, &set);
          if (error)
                  goto out;
          switch (level) {
          case CPU_LEVEL_ROOT:
          case CPU_LEVEL_CPUSET:
                  switch (which) {
                  case CPU_WHICH_TID:
                  case CPU_WHICH_PID:
                          thread_lock(ttd);
                          set = cpuset_ref(ttd->td_cpuset);
                          thread_unlock(ttd);
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                  case CPU_WHICH_DOMAIN:
                          error = EINVAL;
                          goto out;
                  }
                  if (level == CPU_LEVEL_ROOT)
                          nset = cpuset_refroot(set);
                  else
                          nset = cpuset_refbase(set);
                  domainset_copy(nset->cs_domain, &outset);
                  cpuset_rel(nset);
                  break;
          case CPU_LEVEL_WHICH:
                  switch (which) {
                  case CPU_WHICH_TID:
                          thread_lock(ttd);
                          domainset_copy(ttd->td_cpuset->cs_domain, &outset);
                          thread_unlock(ttd);
                          break;
                  case CPU_WHICH_PID:
                          FOREACH_THREAD_IN_PROC(p, ttd) {
                                  thread_lock(ttd);
                                  dset = ttd->td_cpuset->cs_domain;
                                  /* Show all domains in the proc. */
                                  DOMAINSET_OR(&outset.ds_mask, &dset->ds_mask);
                                  /* Last policy wins. */
                                  outset.ds_policy = dset->ds_policy;
                                  outset.ds_prefer = dset->ds_prefer;
                                  thread_unlock(ttd);
                          }
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          domainset_copy(set->cs_domain, &outset);
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                  case CPU_WHICH_DOMAIN:
                          error = EINVAL;
                          break;
                  }
                  break;
          default:
                  error = EINVAL;
                  break;
          }
          if (set)
                  cpuset_rel(set);
          if (p)
                  PROC_UNLOCK(p);
          /*
           * Translate prefer into a set containing only the preferred domain,
           * not the entire fallback set.
           */
          if (outset.ds_policy == DOMAINSET_POLICY_PREFER) {
                  DOMAINSET_ZERO(&outset.ds_mask);
                  DOMAINSET_SET(outset.ds_prefer, &outset.ds_mask);
          }
          DOMAINSET_COPY(&outset.ds_mask, mask);
          if (error == 0)
                  error = copyout(mask, maskp, domainsetsize);
          if (error == 0)
                  if (suword32(policyp, outset.ds_policy) != 0)
                          error = EFAULT;
  out:
          free(mask, M_TEMP);
          return (error);
  }
  
  #ifndef _SYS_SYSPROTO_H_
  struct cpuset_setdomain_args {
          cpulevel_t      level;
          cpuwhich_t      which;
          id_t            id;
          size_t          domainsetsize;
          domainset_t     *mask;
          int             policy;
  };
  #endif
  int
  sys_cpuset_setdomain(struct thread *td, struct cpuset_setdomain_args *uap)
  {
  
          return (kern_cpuset_setdomain(td, uap->level, uap->which,
              uap->id, uap->domainsetsize, uap->mask, uap->policy));
  }
  
  int
  kern_cpuset_setdomain(struct thread *td, cpulevel_t level, cpuwhich_t which,
      id_t id, size_t domainsetsize, const domainset_t *maskp, int policy)
  {
          struct cpuset *nset;
          struct cpuset *set;
          struct thread *ttd;
          struct proc *p;
          struct domainset domain;
          domainset_t *mask;
          int error;
  
          if (domainsetsize < sizeof(domainset_t) ||
              domainsetsize > DOMAINSET_MAXSIZE / NBBY)
                  return (ERANGE);
          if (policy <= DOMAINSET_POLICY_INVALID ||
              policy > DOMAINSET_POLICY_MAX)
                  return (EINVAL);
          error = cpuset_check_capabilities(td, level, which, id);
          if (error != 0)
                  return (error);
          memset(&domain, 0, sizeof(domain));
          mask = malloc(domainsetsize, M_TEMP, M_WAITOK | M_ZERO);
          error = copyin(maskp, mask, domainsetsize);
          if (error)
                  goto out;
          /*
           * Verify that no high bits are set.
           */
          if (domainsetsize > sizeof(domainset_t)) {
                  char *end;
                  char *cp;
  
                  end = cp = (char *)&mask->__bits;
                  end += domainsetsize;
                  cp += sizeof(domainset_t);
                  while (cp != end)
                          if (*cp++ != 0) {
                                  error = EINVAL;
                                  goto out;
                          }
          }
          if (DOMAINSET_EMPTY(mask)) {
                  error = EDEADLK;
                  goto out;
          }
          DOMAINSET_COPY(mask, &domain.ds_mask);
          domain.ds_policy = policy;
  
          /*
           * Sanitize the provided mask.
           */
          if (!DOMAINSET_SUBSET(&all_domains, &domain.ds_mask)) {
                  error = EINVAL;
                  goto out;
          }
  
          /* Translate preferred policy into a mask and fallback. */
          if (policy == DOMAINSET_POLICY_PREFER) {
                  /* Only support a single preferred domain. */
                  if (DOMAINSET_COUNT(&domain.ds_mask) != 1) {
                          error = EINVAL;
                          goto out;
                  }
                  domain.ds_prefer = DOMAINSET_FFS(&domain.ds_mask) - 1;
                  /* This will be constrained by domainset_shadow(). */
                  DOMAINSET_COPY(&all_domains, &domain.ds_mask);
          }
  
          /*
           * When given an impossible policy, fall back to interleaving
           * across all domains.
           */
          if (domainset_empty_vm(&domain))
                  domainset_copy(&domainset2, &domain);
  
          switch (level) {
          case CPU_LEVEL_ROOT:
          case CPU_LEVEL_CPUSET:
                  error = cpuset_which(which, id, &p, &ttd, &set);
                  if (error)
                          break;
                  switch (which) {
                  case CPU_WHICH_TID:
                  case CPU_WHICH_PID:
                          thread_lock(ttd);
                          set = cpuset_ref(ttd->td_cpuset);
                          thread_unlock(ttd);
                          PROC_UNLOCK(p);
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                  case CPU_WHICH_DOMAIN:
                          error = EINVAL;
                          goto out;
                  }
                  if (level == CPU_LEVEL_ROOT)
                          nset = cpuset_refroot(set);
                  else
                          nset = cpuset_refbase(set);
                  error = cpuset_modify_domain(nset, &domain);
                  cpuset_rel(nset);
                  cpuset_rel(set);
                  break;
          case CPU_LEVEL_WHICH:
                  switch (which) {
                  case CPU_WHICH_TID:
                          error = _cpuset_setthread(id, NULL, &domain);
                          break;
                  case CPU_WHICH_PID:
                          error = cpuset_setproc(id, NULL, NULL, &domain, false);
                          break;
                  case CPU_WHICH_CPUSET:
                  case CPU_WHICH_JAIL:
                          error = cpuset_which(which, id, &p, &ttd, &set);
                          if (error == 0) {
                                  error = cpuset_modify_domain(set, &domain);
                                  cpuset_rel(set);
                          }
                          break;
                  case CPU_WHICH_IRQ:
                  case CPU_WHICH_INTRHANDLER:
                  case CPU_WHICH_ITHREAD:
                  default:
                          error = EINVAL;
                          break;
                  }
                  break;
          default:
                  error = EINVAL;
                  break;
          }
  out:
          free(mask, M_TEMP);
          return (error);
  }
  
  #ifdef DDB
  
  static void
  ddb_display_bitset(const struct bitset *set, int size)
  {
          int bit, once;
  
          for (once = 0, bit = 0; bit < size; bit++) {
                  if (CPU_ISSET(bit, set)) {
                          if (once == 0) {
                                  db_printf("%d", bit);
                                  once = 1;
                          } else  
                                  db_printf(",%d", bit);
                  }
          }
          if (once == 0)
                  db_printf("<none>");
  }
  
  void
  ddb_display_cpuset(const cpuset_t *set)
  {
          ddb_display_bitset((const struct bitset *)set, CPU_SETSIZE);
  }
  
  static void
  ddb_display_domainset(const domainset_t *set)
  {
          ddb_display_bitset((const struct bitset *)set, DOMAINSET_SETSIZE);
  }
  
  DB_SHOW_COMMAND(cpusets, db_show_cpusets)
  {
          struct cpuset *set;
  
          LIST_FOREACH(set, &cpuset_ids, cs_link) {
                  db_printf("set=%p id=%-6u ref=%-6d flags=0x%04x parent id=%d\n",
                      set, set->cs_id, refcount_load(&set->cs_ref), set->cs_flags,
                      (set->cs_parent != NULL) ? set->cs_parent->cs_id : 0);
                  db_printf("  cpu mask=");
                  ddb_display_cpuset(&set->cs_mask);
                  db_printf("\n");
                  db_printf("  domain policy %d prefer %d mask=",
                      set->cs_domain->ds_policy, set->cs_domain->ds_prefer);
                  ddb_display_domainset(&set->cs_domain->ds_mask);
                  db_printf("\n");
                  if (db_pager_quit)
                          break;
          }
  }
  
  DB_SHOW_COMMAND(domainsets, db_show_domainsets)
  {
          struct domainset *set;
  
          LIST_FOREACH(set, &cpuset_domains, ds_link) {
                  db_printf("set=%p policy %d prefer %d cnt %d\n",
                      set, set->ds_policy, set->ds_prefer, set->ds_cnt);
                  db_printf("  mask =");
                  ddb_display_domainset(&set->ds_mask);
                  db_printf("\n");
          }
  }
  #endif /* DDB */

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