FreeBSD/Linux Kernel Cross Reference
sys/sys/proc.h

     /*-
      * Copyright (c) 1986, 1989, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
      * the permission of UNIX System Laboratories, Inc.
      *
     * 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, 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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
     *
     *      @(#)proc.h      8.15 (Berkeley) 5/19/95
     * $FreeBSD: releng/5.2/sys/sys/proc.h 122769 2003-11-15 23:57:19Z imp $
     */
    
    #ifndef _SYS_PROC_H_
    #define _SYS_PROC_H_
    
    #include <sys/callout.h>                /* For struct callout. */
    #include <sys/event.h>                  /* For struct klist. */
    #ifndef _KERNEL
    #include <sys/filedesc.h>
    #endif
    #include <sys/_lock.h>
    #include <sys/_mutex.h>
    #include <sys/queue.h>
    #include <sys/priority.h>
    #include <sys/rtprio.h>                 /* XXX. */
    #include <sys/runq.h>
    #include <sys/sigio.h>
    #include <sys/signal.h>
    #ifndef _KERNEL
    #include <sys/time.h>                   /* For structs itimerval, timeval. */
    #else
    #include <sys/pcpu.h>
    #endif
    #include <sys/ucontext.h>
    #include <sys/ucred.h>
    #include <machine/proc.h>               /* Machine-dependent proc substruct. */
    
    /*
     * One structure allocated per session.
     *
     * List of locks
     * (m)          locked by s_mtx mtx
     * (e)          locked by proctree_lock sx
     * (c)          const until freeing
     */
    struct session {
            int             s_count;        /* (m) Ref cnt; pgrps in session. */
            struct proc     *s_leader;      /* (m + e) Session leader. */
            struct vnode    *s_ttyvp;       /* (m) Vnode of controlling tty. */
            struct tty      *s_ttyp;        /* (m) Controlling tty. */
            pid_t           s_sid;          /* (c) Session ID. */
                                            /* (m) Setlogin() name: */
            char            s_login[roundup(MAXLOGNAME, sizeof(long))];
            struct mtx      s_mtx;          /* Mutex to protect members. */
    };
    
    /*
     * One structure allocated per process group.
     *
     * List of locks
     * (m)          locked by pg_mtx mtx
     * (e)          locked by proctree_lock sx
     * (c)          const until freeing
     */
    struct pgrp {
            LIST_ENTRY(pgrp) pg_hash;       /* (e) Hash chain. */
            LIST_HEAD(, proc) pg_members;   /* (m + e) Pointer to pgrp members. */
            struct session  *pg_session;    /* (c) Pointer to session. */
            struct sigiolst pg_sigiolst;    /* (m) List of sigio sources. */
            pid_t           pg_id;          /* (c) Pgrp id. */
           int             pg_jobc;        /* (m) job cntl proc count */
           struct mtx      pg_mtx;         /*  Mutex to protect members */
   };
   
   /*
    * pargs, used to hold a copy of the command line, if it had a sane length.
    */
   struct pargs {
           u_int   ar_ref;         /* Reference count. */
           u_int   ar_length;      /* Length. */
           u_char  ar_args[1];     /* Arguments. */
   };
   
   /*-
    * Description of a process.
    *
    * This structure contains the information needed to manage a thread of
    * control, known in UN*X as a process; it has references to substructures
    * containing descriptions of things that the process uses, but may share
    * with related processes.  The process structure and the substructures
    * are always addressable except for those marked "(CPU)" below,
    * which might be addressable only on a processor on which the process
    * is running.
    *
    * Below is a key of locks used to protect each member of struct proc.  The
    * lock is indicated by a reference to a specific character in parens in the
    * associated comment.
    *      * - not yet protected
    *      a - only touched by curproc or parent during fork/wait
    *      b - created at fork, never changes
    *              (exception aiods switch vmspaces, but they are also
    *              marked 'P_SYSTEM' so hopefully it will be left alone)
    *      c - locked by proc mtx
    *      d - locked by allproc_lock lock
    *      e - locked by proctree_lock lock
    *      f - session mtx
    *      g - process group mtx
    *      h - callout_lock mtx
    *      i - by curproc or the master session mtx
    *      j - locked by sched_lock mtx
    *      k - only accessed by curthread
    *      l - the attaching proc or attaching proc parent
    *      m - Giant
    *      n - not locked, lazy
    *      o - ktrace lock
    *      p - select lock (sellock)
    *      q - td_contested lock
    *      r - p_peers lock
    *      x - created at fork, only changes during single threading in exec
    *      z - zombie threads/kse/ksegroup lock
    *
    * If the locking key specifies two identifiers (for example, p_pptr) then
    * either lock is sufficient for read access, but both locks must be held
    * for write access.
    */
   struct ithd;
   struct ke_sched;
   struct kg_sched;
   struct nlminfo;
   struct p_sched;
   struct td_sched;
   struct trapframe;
   struct turnstile;
   
   /*
    * Here we define the four structures used for process information.
    *
    * The first is the thread. It might be though of as a "Kernel
    * Schedulable Entity Context".
    * This structure contains all the information as to where a thread of
    * execution is now, or was when it was suspended, why it was suspended,
    * and anything else that will be needed to restart it when it is
    * rescheduled. Always associated with a KSE when running, but can be
    * reassigned to an equivalent KSE when being restarted for
    * load balancing. Each of these is associated with a kernel stack
    * and a pcb.
    *
    * It is important to remember that a particular thread structure only
    * exists as long as the system call or kernel entrance (e.g. by pagefault)
    * which it is currently executing. It should therefore NEVER be referenced
    * by pointers in long lived structures that live longer than a single
    * request. If several threads complete their work at the same time,
    * they will all rewind their stacks to the user boundary, report their
    * completion state, and all but one will be freed. That last one will
    * be kept to provide a kernel stack and pcb for the NEXT syscall or kernel
    * entrance. (basically to save freeing and then re-allocating it) The KSE
    * keeps a cached thread available to allow it to quickly
    * get one when it needs a new one. There is also a system
    * cache of free threads. Threads have priority and partake in priority
    * inheritance schemes.
    */
   struct thread;
   
   /*
    * The second structure is the Kernel Schedulable Entity. (KSE)
    * It represents the ability to take a slot in the scheduler queue.
    * As long as this is scheduled, it could continue to run any threads that
    * are assigned to the KSEGRP (see later) until either it runs out
    * of runnable threads of high enough priority, or CPU.
    * It runs on one CPU and is assigned a quantum of time. When a thread is
    * blocked, The KSE continues to run and will search for another thread
    * in a runnable state amongst those it has. It May decide to return to user
    * mode with a new 'empty' thread if there are no runnable threads.
    * Threads are temporarily associated with a KSE for scheduling reasons.
    */
   struct kse;
   
   /*
    * The KSEGRP is allocated resources across a number of CPUs.
    * (Including a number of CPUxQUANTA. It parcels these QUANTA up among
    * its KSEs, each of which should be running in a different CPU.
    * BASE priority and total available quanta are properties of a KSEGRP.
    * Multiple KSEGRPs in a single process compete against each other
    * for total quanta in the same way that a forked child competes against
    * it's parent process.
    */
   struct ksegrp;
   
   /*
    * A process is the owner of all system resources allocated to a task
    * except CPU quanta.
    * All KSEGs under one process see, and have the same access to, these
    * resources (e.g. files, memory, sockets, permissions kqueues).
    * A process may compete for CPU cycles on the same basis as a
    * forked process cluster by spawning several KSEGRPs.
    */
   struct proc;
   
   /***************
    * In pictures:
    With a single run queue used by all processors:
   
    RUNQ: --->KSE---KSE--...               SLEEPQ:[]---THREAD---THREAD---THREAD
              |   /                               []---THREAD
              KSEG---THREAD--THREAD--THREAD       []
                                                  []---THREAD---THREAD
   
     (processors run THREADs from the KSEG until they are exhausted or
     the KSEG exhausts its quantum)
   
   With PER-CPU run queues:
   KSEs on the separate run queues directly
   They would be given priorities calculated from the KSEG.
   
    *
    *****************/
   
   /*
    * Kernel runnable context (thread).
    * This is what is put to sleep and reactivated.
    * The first KSE available in the correct group will run this thread.
    * If several are available, use the one on the same CPU as last time.
    * When waiting to be run, threads are hung off the KSEGRP in priority order.
    * with N runnable and queued KSEs in the KSEGRP, the first N threads
    * are linked to them. Other threads are not yet assigned.
    */
   struct thread {
           struct proc     *td_proc;       /* (*) Associated process. */
           struct ksegrp   *td_ksegrp;     /* (*) Associated KSEG. */
           TAILQ_ENTRY(thread) td_plist;   /* (*) All threads in this proc. */
           TAILQ_ENTRY(thread) td_kglist;  /* (*) All threads in this ksegrp. */
   
           /* The two queues below should someday be merged. */
           TAILQ_ENTRY(thread) td_slpq;    /* (j) Sleep queue. */
           TAILQ_ENTRY(thread) td_lockq;   /* (j) Lock queue. */
           TAILQ_ENTRY(thread) td_runq;    /* (j/z) Run queue(s). XXXKSE */
   
           TAILQ_HEAD(, selinfo) td_selq;  /* (p) List of selinfos. */
           struct turnstile *td_turnstile; /* (k) Associated turnstile. */
   
   /* Cleared during fork1() or thread_sched_upcall(). */
   #define td_startzero td_flags
           int             td_flags;       /* (j) TDF_* flags. */
           int             td_inhibitors;  /* (j) Why can not run. */
           int             td_pflags;      /* (k) Private thread (TDP_*) flags. */
           struct kse      *td_last_kse;   /* (j) Previous value of td_kse. */
           struct kse      *td_kse;        /* (j) Current KSE if running. */
           int             td_dupfd;       /* (k) Ret value from fdopen. XXX */
           void            *td_wchan;      /* (j) Sleep address. */
           const char      *td_wmesg;      /* (j) Reason for sleep. */
           u_char          td_lastcpu;     /* (j) Last cpu we were on. */
           u_char          td_oncpu;       /* (j) Which cpu we are on. */
           short           td_locks;       /* (k) DEBUG: lockmgr count of locks. */
           struct turnstile *td_blocked;   /* (j) Lock process is blocked on. */
           struct ithd     *td_ithd;       /* (b) For interrupt threads only. */
           const char      *td_lockname;   /* (j) Name of lock blocked on. */
           LIST_HEAD(, turnstile) td_contested;    /* (q) Contested locks. */
           struct lock_list_entry *td_sleeplocks; /* (k) Held sleep locks. */
           int             td_intr_nesting_level; /* (k) Interrupt recursion. */
           int             td_pinned;      /* (k) Temporary cpu pin count. */
           struct kse_thr_mailbox *td_mailbox; /* (*) Userland mailbox address. */
           struct ucred    *td_ucred;      /* (k) Reference to credentials. */
           struct thread   *td_standin;    /* (*) Use this for an upcall. */
           u_int           td_prticks;     /* (*) Profclock hits in sys for user */
           struct kse_upcall *td_upcall;   /* (*) Upcall structure. */
           u_int64_t       td_sticks;      /* (j) Statclock hits in system mode. */
           u_int           td_uuticks;     /* (*) Statclock in user, for UTS. */
           u_int           td_usticks;     /* (*) Statclock in kernel, for UTS. */
           int             td_intrval;     /* (*) Return value of TDF_INTERRUPT. */
           sigset_t        td_oldsigmask;  /* (k) Saved mask from pre sigpause. */
           sigset_t        td_sigmask;     /* (c) Current signal mask. */
           sigset_t        td_siglist;     /* (c) Sigs arrived, not delivered. */
           sigset_t        *td_waitset;    /* (c) Wait set for sigwait. */
           TAILQ_ENTRY(thread) td_umtx;    /* (c?) Link for when we're blocked. */
           volatile u_int  td_generation;  /* (k) Enable detection of preemption */
   
   #define td_endzero td_base_pri
   
   /* Copied during fork1() or thread_sched_upcall(). */
   #define td_startcopy td_endzero
           u_char          td_base_pri;    /* (j) Thread base kernel priority. */
           u_char          td_priority;    /* (j) Thread active priority. */
   #define td_endcopy td_pcb
   
   /*
    * fields that must be manually set in fork1() or thread_sched_upcall()
    * or already have been set in the allocator, contstructor, etc..
    */
           struct pcb      *td_pcb;        /* (k) Kernel VA of pcb and kstack. */
           enum {
                   TDS_INACTIVE = 0x0,
                   TDS_INHIBITED,
                   TDS_CAN_RUN,
                   TDS_RUNQ,
                   TDS_RUNNING
           } td_state;
           register_t      td_retval[2];   /* (k) Syscall aux returns. */
           struct callout  td_slpcallout;  /* (h) Callout for sleep. */
           struct trapframe *td_frame;     /* (k) */
           struct vm_object *td_kstack_obj;/* (a) Kstack object. */
           vm_offset_t     td_kstack;      /* (a) Kernel VA of kstack. */
           int             td_kstack_pages; /* (a) Size of the kstack. */
           struct vm_object *td_altkstack_obj;/* (a) Alternate kstack object. */
           vm_offset_t     td_altkstack;   /* (a) Kernel VA of alternate kstack. */
           int             td_altkstack_pages; /* (a) Size of the alternate kstack */
           u_int           td_critnest;    /* (k) Critical section nest level. */
           struct mdthread td_md;          /* (k) Any machine-dependent fields. */
           struct td_sched *td_sched;      /* (*) Scheduler-specific data. */
   };
   /* flags kept in td_flags */ 
   #define TDF_INPANIC     0x000002 /* Caused a panic, let it drive crashdump. */
   #define TDF_CAN_UNBIND  0x000004 /* Only temporarily bound. */
   #define TDF_SINTR       0x000008 /* Sleep is interruptible. */
   #define TDF_TIMEOUT     0x000010 /* Timing out during sleep. */
   #define TDF_IDLETD      0x000020 /* This is one of the per-CPU idle threads. */
   #define TDF_SELECT      0x000040 /* Selecting; wakeup/waiting danger. */
   #define TDF_CVWAITQ     0x000080 /* Thread is on a cv_waitq (not slpq). */
   #define TDF_TSNOBLOCK   0x000100 /* Don't block on a turnstile due to race. */
   #define TDF_ONSLEEPQ    0x000200 /* On the sleep queue. */
   #define TDF_ASTPENDING  0x000800 /* Thread has some asynchronous events. */
   #define TDF_TIMOFAIL    0x001000 /* Timeout from sleep after we were awake. */
   #define TDF_INTERRUPT   0x002000 /* Thread is marked as interrupted. */
   #define TDF_USTATCLOCK  0x004000 /* Stat clock hits in userland. */
   #define TDF_OWEUPC      0x008000 /* Owe thread an addupc() call at next AST. */
   #define TDF_NEEDRESCHED 0x010000 /* Thread needs to yield. */
   #define TDF_NEEDSIGCHK  0x020000 /* Thread may need signal delivery. */
   #define TDF_SA          0x040000 /* A scheduler activation based thread. */
   #define TDF_UMTXWAKEUP  0x080000 /* Libthr thread must not sleep on a umtx. */
   #define TDF_DEADLKTREAT 0x800000 /* Lock aquisition - deadlock treatment. */
   
   /* "private" flags kept in td_pflags */
   #define TDP_OLDMASK     0x0001 /* Need to restore mask after suspend. */
   #define TDP_INKTR       0x0002 /* Thread is currently in KTR code. */
   #define TDP_INKTRACE    0x0004 /* Thread is currently in KTRACE code. */
   #define TDP_UPCALLING   0x0008 /* This thread is doing an upcall. */
   #define TDP_COWINPROGRESS 0x0010 /* Snapshot copy-on-write in progress. */
   
   #define TDI_SUSPENDED   0x0001  /* On suspension queue. */
   #define TDI_SLEEPING    0x0002  /* Actually asleep! (tricky). */
   #define TDI_SWAPPED     0x0004  /* Stack not in mem.. bad juju if run. */
   #define TDI_LOCK        0x0008  /* Stopped on a lock. */
   #define TDI_IWAIT       0x0010  /* Awaiting interrupt. */
   
   #define TD_CAN_UNBIND(td)                                       \
       (((td)->td_flags & TDF_CAN_UNBIND) == TDF_CAN_UNBIND &&     \
        ((td)->td_upcall != NULL))
   
   #define TD_IS_SLEEPING(td)      ((td)->td_inhibitors & TDI_SLEEPING)
   #define TD_ON_SLEEPQ(td)        ((td)->td_wchan != NULL)
   #define TD_IS_SUSPENDED(td)     ((td)->td_inhibitors & TDI_SUSPENDED)
   #define TD_IS_SWAPPED(td)       ((td)->td_inhibitors & TDI_SWAPPED)
   #define TD_ON_LOCK(td)          ((td)->td_inhibitors & TDI_LOCK)
   #define TD_AWAITING_INTR(td)    ((td)->td_inhibitors & TDI_IWAIT)
   #define TD_IS_RUNNING(td)       ((td)->td_state == TDS_RUNNING)
   #define TD_ON_RUNQ(td)          ((td)->td_state == TDS_RUNQ)
   #define TD_CAN_RUN(td)          ((td)->td_state == TDS_CAN_RUN)
   #define TD_IS_INHIBITED(td)     ((td)->td_state == TDS_INHIBITED)
   
   #define TD_SET_INHIB(td, inhib) do {                    \
           (td)->td_state = TDS_INHIBITED;                 \
           (td)->td_inhibitors |= (inhib);                 \
   } while (0)
   
   #define TD_CLR_INHIB(td, inhib) do {                    \
           if (((td)->td_inhibitors & (inhib)) &&          \
               (((td)->td_inhibitors &= ~(inhib)) == 0))   \
                   (td)->td_state = TDS_CAN_RUN;           \
   } while (0)
   
   #define TD_SET_SLEEPING(td)     TD_SET_INHIB((td), TDI_SLEEPING)
   #define TD_SET_SWAPPED(td)      TD_SET_INHIB((td), TDI_SWAPPED)
   #define TD_SET_LOCK(td)         TD_SET_INHIB((td), TDI_LOCK)
   #define TD_SET_SUSPENDED(td)    TD_SET_INHIB((td), TDI_SUSPENDED)
   #define TD_SET_IWAIT(td)        TD_SET_INHIB((td), TDI_IWAIT)
   #define TD_SET_EXITING(td)      TD_SET_INHIB((td), TDI_EXITING)
   
   #define TD_CLR_SLEEPING(td)     TD_CLR_INHIB((td), TDI_SLEEPING)
   #define TD_CLR_SWAPPED(td)      TD_CLR_INHIB((td), TDI_SWAPPED)
   #define TD_CLR_LOCK(td)         TD_CLR_INHIB((td), TDI_LOCK)
   #define TD_CLR_SUSPENDED(td)    TD_CLR_INHIB((td), TDI_SUSPENDED)
   #define TD_CLR_IWAIT(td)        TD_CLR_INHIB((td), TDI_IWAIT)
   
   #define TD_SET_RUNNING(td)      do {(td)->td_state = TDS_RUNNING; } while (0)
   #define TD_SET_RUNQ(td)         do {(td)->td_state = TDS_RUNQ; } while (0)
   #define TD_SET_CAN_RUN(td)      do {(td)->td_state = TDS_CAN_RUN; } while (0)
   #define TD_SET_ON_SLEEPQ(td)    do {(td)->td_flags |= TDF_ONSLEEPQ; } while (0)
   #define TD_CLR_ON_SLEEPQ(td)    do {                    \
                   (td)->td_flags &= ~TDF_ONSLEEPQ;        \
                   (td)->td_wchan = NULL;                  \
   } while (0)
   
   /*
    * The schedulable entity that can be given a context to run.
    * A process may have several of these. Probably one per processor
    * but posibly a few more. In this universe they are grouped
    * with a KSEG that contains the priority and niceness
    * for the group.
    */
   struct kse {
           struct proc     *ke_proc;       /* (*) Associated process. */
           struct ksegrp   *ke_ksegrp;     /* (*) Associated KSEG. */
           TAILQ_ENTRY(kse) ke_kglist;     /* (*) Queue of KSEs in ke_ksegrp. */
           TAILQ_ENTRY(kse) ke_kgrlist;    /* (*) Queue of KSEs in this state. */
           TAILQ_ENTRY(kse) ke_procq;      /* (j/z) Run queue. */
   
   #define ke_startzero ke_flags
           int             ke_flags;       /* (j) KEF_* flags. */
           struct thread   *ke_thread;     /* (*) Active associated thread. */
           fixpt_t         ke_pctcpu;      /* (j) %cpu during p_swtime. */
           u_char          ke_oncpu;       /* (j) Which cpu we are on. */
           char            ke_rqindex;     /* (j) Run queue index. */
           enum {
                   KES_UNUSED = 0x0,
                   KES_IDLE,
                   KES_ONRUNQ,
                   KES_UNQUEUED,           /* in transit */
                   KES_THREAD              /* slaved to thread state */
           } ke_state;                     /* (j) KSE status. */
   #define ke_endzero ke_dummy
           u_char          ke_dummy;
           struct ke_sched *ke_sched;      /* (*) Scheduler-specific data. */
   };
   
   /* flags kept in ke_flags */
   #define KEF_SCHED0      0x00001 /* For scheduler-specific use. */
   #define KEF_SCHED1      0x00002 /* For scheduler-specific use. */
   #define KEF_SCHED2      0X00004 /* For scheduler-specific use. */
   #define KEF_SCHED3      0x00008 /* For scheduler-specific use. */
   #define KEF_DIDRUN      0x02000 /* KSE actually ran. */
   #define KEF_EXIT        0x04000 /* KSE is being killed. */
   
   /*
    * The upcall management structure.
    * The upcall is used when returning to userland.  If a thread does not have
    * an upcall on return to userland the thread exports its context and exits.
    */
   struct kse_upcall {
           TAILQ_ENTRY(kse_upcall) ku_link;        /* List of upcalls in KSEG. */
           struct ksegrp           *ku_ksegrp;     /* Associated KSEG. */
           struct thread           *ku_owner;      /* owning thread */
           int                     ku_flags;       /* KUF_* flags. */
           struct kse_mailbox      *ku_mailbox;    /* userland mailbox address. */
           stack_t                 ku_stack;       /* userland upcall stack. */
           void                    *ku_func;       /* userland upcall function. */
           unsigned int            ku_mflags;      /* cached upcall mailbox flags */
   };
   
   #define KUF_DOUPCALL    0x00001         /* Do upcall now, don't wait. */
   #define KUF_EXITING     0x00002         /* Upcall structure is exiting. */
   
   /*
    * Kernel-scheduled entity group (KSEG).  The scheduler considers each KSEG to
    * be an indivisible unit from a time-sharing perspective, though each KSEG may
    * contain multiple KSEs.
    */
   struct ksegrp {
           struct proc     *kg_proc;       /* (*) Process that contains this KSEG. */
           TAILQ_ENTRY(ksegrp) kg_ksegrp;  /* (*) Queue of KSEGs in kg_proc. */
           TAILQ_HEAD(, kse) kg_kseq;      /* (ke_kglist) All KSEs. */
           TAILQ_HEAD(, kse) kg_iq;        /* (ke_kgrlist) All idle KSEs. */
           TAILQ_HEAD(, thread) kg_threads;/* (td_kglist) All threads. */
           TAILQ_HEAD(, thread) kg_runq;   /* (td_runq) waiting RUNNABLE threads */
           TAILQ_HEAD(, thread) kg_slpq;   /* (td_runq) NONRUNNABLE threads. */
           TAILQ_HEAD(, kse_upcall) kg_upcalls;    /* All upcalls in the group. */
   #define kg_startzero kg_estcpu
           u_int           kg_estcpu;      /* (j) Sum of the same field in KSEs. */
           u_int           kg_slptime;     /* (j) How long completely blocked. */
           struct thread   *kg_last_assigned; /* (j) Last thread assigned to a KSE. */
           int             kg_runnable;    /* (j) Num runnable threads on queue. */
           int             kg_runq_kses;   /* (j) Num KSEs on runq. */
           int             kg_idle_kses;   /* (j) Num KSEs on iq. */
           int             kg_numupcalls;  /* (j) Num upcalls. */
           int             kg_upsleeps;    /* (c) Num threads in kse_release(). */
           struct kse_thr_mailbox *kg_completed; /* (c) Completed thread mboxes. */
           int             kg_nextupcall;  /* (*) Next upcall time. */
           int             kg_upquantum;   /* (*) Quantum to schedule an upcall. */
   #define kg_endzero kg_pri_class
   
   #define kg_startcopy    kg_endzero
           u_char          kg_pri_class;   /* (j) Scheduling class. */
           u_char          kg_user_pri;    /* (j) User pri from estcpu and nice. */
           char            kg_nice;        /* (c + j) Process "nice" value. */
   #define kg_endcopy kg_numthreads
           int             kg_numthreads;  /* (j) Num threads in total. */
           int             kg_kses;        /* (j) Num KSEs in group. */
           struct kg_sched *kg_sched;      /* (*) Scheduler-specific data. */
   };
   
   /*
    * The old fashionned process. May have multiple threads, KSEGRPs
    * and KSEs. Starts off with a single embedded KSEGRP, KSE and THREAD.
    */
   struct proc {
           LIST_ENTRY(proc) p_list;        /* (d) List of all processes. */
           TAILQ_HEAD(, ksegrp) p_ksegrps; /* (kg_ksegrp) All KSEGs. */
           TAILQ_HEAD(, thread) p_threads; /* (td_plist) Threads. (shortcut) */
           TAILQ_HEAD(, thread) p_suspended; /* (td_runq) Suspended threads. */
           struct ucred    *p_ucred;       /* (c) Process owner's identity. */
           struct filedesc *p_fd;          /* (b) Ptr to open files structure. */
           struct filedesc_to_leader *p_fdtol; /* (b) Ptr to tracking node */
                                           /* Accumulated stats for all KSEs? */
           struct pstats   *p_stats;       /* (b) Accounting/statistics (CPU). */
           struct plimit   *p_limit;       /* (c*) Process limits. */
           struct vm_object *p_upages_obj; /* (a) Upages object. */
           struct sigacts  *p_sigacts;     /* (x) Signal actions, state (CPU). */
   
           /*struct ksegrp p_ksegrp;
           struct kse      p_kse; */
   
           /*
            * The following don't make too much sense..
            * See the td_ or ke_ versions of the same flags
            */
           int             p_flag;         /* (c) P_* flags. */
           int             p_sflag;        /* (j) PS_* flags. */
           enum {
                   PRS_NEW = 0,            /* In creation */
                   PRS_NORMAL,             /* KSEs can be run. */
                   PRS_ZOMBIE
           } p_state;                      /* (j/c) S* process status. */
           pid_t           p_pid;          /* (b) Process identifier. */
           LIST_ENTRY(proc) p_hash;        /* (d) Hash chain. */
           LIST_ENTRY(proc) p_pglist;      /* (g + e) List of processes in pgrp. */
           struct proc     *p_pptr;        /* (c + e) Pointer to parent process. */
           LIST_ENTRY(proc) p_sibling;     /* (e) List of sibling processes. */
           LIST_HEAD(, proc) p_children;   /* (e) Pointer to list of children. */
           struct mtx      p_mtx;          /* (n) Lock for this struct. */
   
   /* The following fields are all zeroed upon creation in fork. */
   #define p_startzero     p_oppid
           pid_t           p_oppid;        /* (c + e) Save ppid in ptrace. XXX */
           struct vmspace  *p_vmspace;     /* (b) Address space. */
           u_int           p_swtime;       /* (j) Time swapped in or out. */
           struct itimerval p_realtimer;   /* (c) Alarm timer. */
           struct bintime  p_runtime;      /* (j) Real time. */
           u_int64_t       p_uu;           /* (j) Previous user time in usec. */
           u_int64_t       p_su;           /* (j) Previous system time in usec. */
           u_int64_t       p_iu;           /* (j) Previous intr time in usec. */
           u_int64_t       p_uticks;       /* (j) Statclock hits in user mode. */
           u_int64_t       p_sticks;       /* (j) Statclock hits in system mode. */
           u_int64_t       p_iticks;       /* (j) Statclock hits in intr. */
           int             p_profthreads;  /* (c) Num threads in addupc_task. */
           int             p_maxthrwaits;  /* (c) Max threads num waiters */
           int             p_traceflag;    /* (o) Kernel trace points. */
           struct vnode    *p_tracevp;     /* (c + o) Trace to vnode. */
           struct ucred    *p_tracecred;   /* (o) Credentials to trace with. */
           struct vnode    *p_textvp;      /* (b) Vnode of executable. */
           sigset_t        p_siglist;      /* (c) Sigs not delivered to a td. */
           char            p_lock;         /* (c) Proclock (prevent swap) count. */
           struct klist    p_klist;        /* (c) Knotes attached to this proc. */
           struct sigiolst p_sigiolst;     /* (c) List of sigio sources. */
           int             p_sigparent;    /* (c) Signal to parent on exit. */
           int             p_sig;          /* (n) For core dump/debugger XXX. */
           u_long          p_code;         /* (n) For core dump/debugger XXX. */
           u_int           p_stops;        /* (c) Stop event bitmask. */
           u_int           p_stype;        /* (c) Stop event type. */
           char            p_step;         /* (c) Process is stopped. */
           u_char          p_pfsflags;     /* (c) Procfs flags. */
           struct nlminfo  *p_nlminfo;     /* (?) Only used by/for lockd. */
           void            *p_aioinfo;     /* (?) ASYNC I/O info. */
           struct thread   *p_singlethread;/* (c + j) If single threading this is it */
           int             p_suspcount;    /* (c) # threads in suspended mode */
   /* End area that is zeroed on creation. */
   #define p_endzero       p_sigstk
   
   /* The following fields are all copied upon creation in fork. */
   #define p_startcopy     p_endzero
           stack_t         p_sigstk;       /* (c) Stack ptr and on-stack flag. */
           u_int           p_magic;        /* (b) Magic number. */
           char            p_comm[MAXCOMLEN + 1];  /* (b) Process name. */
           struct pgrp     *p_pgrp;        /* (c + e) Pointer to process group. */
           struct sysentvec *p_sysent;     /* (b) Syscall dispatch info. */
           struct pargs    *p_args;        /* (c) Process arguments. */
           rlim_t          p_cpulimit;     /* (j) Current CPU limit in seconds. */
   /* End area that is copied on creation. */
   #define p_endcopy       p_xstat
   
           u_short         p_xstat;        /* (c) Exit status; also stop sig. */
           int             p_numthreads;   /* (j) Number of threads. */
           int             p_numksegrps;   /* (?) number of ksegrps */
           struct mdproc   p_md;           /* Any machine-dependent fields. */
           struct callout  p_itcallout;    /* (h + c) Interval timer callout. */
           struct user     *p_uarea;       /* (k) Kernel VA of u-area (CPU). */
           u_short         p_acflag;       /* (c) Accounting flags. */
           struct rusage   *p_ru;          /* (a) Exit information. XXX */
           struct proc     *p_peers;       /* (r) */
           struct proc     *p_leader;      /* (b) */
           void            *p_emuldata;    /* (c) Emulator state data. */
           struct label    *p_label;       /* (*) Proc (not subject) MAC label. */
           struct p_sched  *p_sched;       /* (*) Scheduler-specific data. */
   };
   
   #define p_rlimit        p_limit->pl_rlimit
   #define p_session       p_pgrp->pg_session
   #define p_pgid          p_pgrp->pg_id
   
   #define NOCPU   0xff            /* For when we aren't on a CPU. (SMP) */
   
   /* Status values (p_stat). */
   
   /* These flags are kept in p_flag. */
   #define P_ADVLOCK       0x00001 /* Process may hold a POSIX advisory lock. */
   #define P_CONTROLT      0x00002 /* Has a controlling terminal. */
   #define P_KTHREAD       0x00004 /* Kernel thread. (*)*/
   #define P_NOLOAD        0x00008 /* Ignore during load avg calculations. */
   #define P_PPWAIT        0x00010 /* Parent is waiting for child to exec/exit. */
   #define P_PROFIL        0x00020 /* Has started profiling. */
   #define P_STOPPROF      0x00040 /* Has thread in requesting to stop prof */
   #define P_SUGID         0x00100 /* Had set id privileges since last exec. */
   #define P_SYSTEM        0x00200 /* System proc: no sigs, stats or swapping. */
   #define P_SINGLE_EXIT   0x00400 /* Threads suspending should exit, not wait. */
   #define P_TRACED        0x00800 /* Debugged process being traced. */
   #define P_WAITED        0x01000 /* Someone is waiting for us. */
   #define P_WEXIT         0x02000 /* Working on exiting. */
   #define P_EXEC          0x04000 /* Process called exec. */
   #define P_SA            0x08000 /* Using scheduler activations. */
   #define P_CONTINUED     0x10000 /* Proc has continued from a stopped state. */
   #define P_STOPPED_SIG   0x20000 /* Stopped due to SIGSTOP/SIGTSTP. */
   #define P_STOPPED_TRACE 0x40000 /* Stopped because of tracing. */
   #define P_STOPPED_SINGLE        0x80000 /* Only one thread can continue */
                                           /* (not to user) */
   #define P_PROTECTED     0x100000 /* Do not kill on memory overcommit. */
   #define P_SIGEVENT      0x200000 /* Process pending signals changed. */
   
   #define P_JAILED        0x1000000 /* Process is in jail. */
   #define P_ALTSTACK      0x2000000 /* Have alternate signal stack. */
   #define P_INEXEC        0x4000000 /* Process is in execve(). */
   
   #define P_STOPPED               (P_STOPPED_SIG|P_STOPPED_SINGLE|P_STOPPED_TRACE)
   #define P_SHOULDSTOP(p)         ((p)->p_flag & P_STOPPED)
   
   /* These flags are kept in p_sflag and are protected with sched_lock. */
   #define PS_INMEM        0x00001 /* Loaded into memory. */
   #define PS_XCPU         0x00002 /* Exceeded CPU limit. */
   #define PS_ALRMPEND     0x00020 /* Pending SIGVTALRM needs to be posted. */
   #define PS_PROFPEND     0x00040 /* Pending SIGPROF needs to be posted. */
   #define PS_SWAPINREQ    0x00100 /* Swapin request due to wakeup. */
   #define PS_SWAPPINGOUT  0x00200 /* Process is being swapped out. */
   #define PS_SWAPPINGIN   0x04000 /* Process is being swapped in. */
   #define PS_MACPEND      0x08000 /* Ast()-based MAC event pending. */
   
   /* used only in legacy conversion code */
   #define SIDL    1               /* Process being created by fork. */
   #define SRUN    2               /* Currently runnable. */
   #define SSLEEP  3               /* Sleeping on an address. */
   #define SSTOP   4               /* Process debugging or suspension. */
   #define SZOMB   5               /* Awaiting collection by parent. */
   #define SWAIT   6               /* Waiting for interrupt. */
   #define SLOCK   7               /* Blocked on a lock. */
   
   #define P_MAGIC         0xbeefface
   
   #ifdef _KERNEL
   
   #ifdef MALLOC_DECLARE
   MALLOC_DECLARE(M_PARGS);
   MALLOC_DECLARE(M_PGRP);
   MALLOC_DECLARE(M_SESSION);
   MALLOC_DECLARE(M_SUBPROC);
   MALLOC_DECLARE(M_ZOMBIE);
   #endif
   
   #define FOREACH_PROC_IN_SYSTEM(p)                                       \
           LIST_FOREACH((p), &allproc, p_list)
   #define FOREACH_KSEGRP_IN_PROC(p, kg)                                   \
           TAILQ_FOREACH((kg), &(p)->p_ksegrps, kg_ksegrp)
   #define FOREACH_THREAD_IN_GROUP(kg, td)                                 \
           TAILQ_FOREACH((td), &(kg)->kg_threads, td_kglist)
   #define FOREACH_KSE_IN_GROUP(kg, ke)                                    \
           TAILQ_FOREACH((ke), &(kg)->kg_kseq, ke_kglist)
   #define FOREACH_UPCALL_IN_GROUP(kg, ku)                                 \
           TAILQ_FOREACH((ku), &(kg)->kg_upcalls, ku_link)
   #define FOREACH_THREAD_IN_PROC(p, td)                                   \
           TAILQ_FOREACH((td), &(p)->p_threads, td_plist)
   
   /* XXXKSE the lines below should probably only be used in 1:1 code */
   #define FIRST_THREAD_IN_PROC(p) TAILQ_FIRST(&(p)->p_threads)
   #define FIRST_KSEGRP_IN_PROC(p) TAILQ_FIRST(&(p)->p_ksegrps)
   #define FIRST_KSE_IN_KSEGRP(kg) TAILQ_FIRST(&(kg)->kg_kseq)
   #define FIRST_KSE_IN_PROC(p)    FIRST_KSE_IN_KSEGRP(FIRST_KSEGRP_IN_PROC(p))
   
   /*
    * We use process IDs <= PID_MAX; PID_MAX + 1 must also fit in a pid_t,
    * as it is used to represent "no process group".
    */
   #define PID_MAX         99999
   #define NO_PID          100000
   
   #define SESS_LEADER(p)  ((p)->p_session->s_leader == (p))
   #define SESSHOLD(s)     ((s)->s_count++)
   #define SESSRELE(s) {                                                   \
           if (--(s)->s_count == 0)                                        \
                   FREE(s, M_SESSION);                                     \
   }
   
   #define STOPEVENT(p, e, v) do {                                         \
           PROC_LOCK(p);                                                   \
           _STOPEVENT((p), (e), (v));                                      \
           PROC_UNLOCK(p);                                                 \
   } while (0)
   #define _STOPEVENT(p, e, v) do {                                        \
           PROC_LOCK_ASSERT(p, MA_OWNED);                                  \
           if ((p)->p_stops & (e))                                         \
                   stopevent((p), (e), (v));                               \
   } while (0)
   
   /* Lock and unlock a process. */
   #define PROC_LOCK(p)    mtx_lock(&(p)->p_mtx)
   #define PROC_TRYLOCK(p) mtx_trylock(&(p)->p_mtx)
   #define PROC_UNLOCK(p)  mtx_unlock(&(p)->p_mtx)
   #define PROC_LOCKED(p)  mtx_owned(&(p)->p_mtx)
   #define PROC_LOCK_ASSERT(p, type)       mtx_assert(&(p)->p_mtx, (type))
   
   /* Lock and unlock a process group. */
   #define PGRP_LOCK(pg)   mtx_lock(&(pg)->pg_mtx)
   #define PGRP_UNLOCK(pg) mtx_unlock(&(pg)->pg_mtx)
   #define PGRP_LOCKED(pg) mtx_owned(&(pg)->pg_mtx)
   #define PGRP_LOCK_ASSERT(pg, type)      mtx_assert(&(pg)->pg_mtx, (type))
   
   #define PGRP_LOCK_PGSIGNAL(pg) do {                                     \
           if ((pg) != NULL)                                               \
                   PGRP_LOCK(pg);                                          \
   } while (0)
   #define PGRP_UNLOCK_PGSIGNAL(pg) do {                                   \
           if ((pg) != NULL)                                               \
                   PGRP_UNLOCK(pg);                                        \
   } while (0)
   
   /* Lock and unlock a session. */
   #define SESS_LOCK(s)    mtx_lock(&(s)->s_mtx)
   #define SESS_UNLOCK(s)  mtx_unlock(&(s)->s_mtx)
   #define SESS_LOCKED(s)  mtx_owned(&(s)->s_mtx)
   #define SESS_LOCK_ASSERT(s, type)       mtx_assert(&(s)->s_mtx, (type))
   
   /* Hold process U-area in memory, normally for ptrace/procfs work. */
   #define PHOLD(p) do {                                                   \
           PROC_LOCK(p);                                                   \
           _PHOLD(p);                                                      \
           PROC_UNLOCK(p);                                                 \
   } while (0)
   #define _PHOLD(p) do {                                                  \
           PROC_LOCK_ASSERT((p), MA_OWNED);                                \
           (p)->p_lock++;                                                  \
           if (((p)->p_sflag & PS_INMEM) == 0)                             \
                   faultin((p));                                           \
   } while (0)
   
   #define PRELE(p) do {                                                   \
           PROC_LOCK((p));                                                 \
           _PRELE((p));                                                    \
           PROC_UNLOCK((p));                                               \
   } while (0)
   #define _PRELE(p) do {                                                  \
           PROC_LOCK_ASSERT((p), MA_OWNED);                                \
           (--(p)->p_lock);                                                \
   } while (0)
   
   /* Check whether a thread is safe to be swapped out. */
   #define thread_safetoswapout(td) (TD_IS_SLEEPING(td) || TD_IS_SUSPENDED(td))
   
   /* Lock and unlock process arguments. */
   #define PARGS_LOCK(p)           mtx_lock(&pargs_ref_lock)
   #define PARGS_UNLOCK(p)         mtx_unlock(&pargs_ref_lock)
   
   #define PIDHASH(pid)    (&pidhashtbl[(pid) & pidhash])
   extern LIST_HEAD(pidhashhead, proc) *pidhashtbl;
   extern u_long pidhash;
   
   #define PGRPHASH(pgid)  (&pgrphashtbl[(pgid) & pgrphash])
   extern LIST_HEAD(pgrphashhead, pgrp) *pgrphashtbl;
   extern u_long pgrphash;
   
   extern struct sx allproc_lock;
   extern struct sx proctree_lock;
   extern struct mtx pargs_ref_lock;
   extern struct mtx ppeers_lock;
   extern struct proc proc0;               /* Process slot for swapper. */
   extern struct thread thread0;           /* Primary thread in proc0. */
   extern struct ksegrp ksegrp0;           /* Primary ksegrp in proc0. */
   extern struct kse kse0;                 /* Primary kse in proc0. */
   extern struct vmspace vmspace0;         /* VM space for proc0. */
   extern int hogticks;                    /* Limit on kernel cpu hogs. */
   extern int nprocs, maxproc;             /* Current and max number of procs. */
   extern int maxprocperuid;               /* Max procs per uid. */
   extern u_long ps_arg_cache_limit;
   extern int ps_argsopen;
   extern int sched_quantum;               /* Scheduling quantum in ticks. */
   
   LIST_HEAD(proclist, proc);
   TAILQ_HEAD(procqueue, proc);
   TAILQ_HEAD(threadqueue, thread);
   extern struct proclist allproc;         /* List of all processes. */
   extern struct proclist zombproc;        /* List of zombie processes. */
   extern struct proc *initproc, *pageproc; /* Process slots for init, pager. */
   extern struct proc *updateproc;         /* Process slot for syncer (sic). */
   
   extern struct uma_zone *proc_zone;
   
   extern int lastpid;
   
   struct  proc *pfind(pid_t);     /* Find process by id. */
   struct  pgrp *pgfind(pid_t);    /* Find process group by id. */
   struct  proc *zpfind(pid_t);    /* Find zombie process by id. */
   
   void    adjustrunqueue(struct thread *, int newpri);
   void    ast(struct trapframe *framep);
   struct  thread *choosethread(void);
   int     cr_cansignal(struct ucred *cred, struct proc *proc, int signum);
   int     enterpgrp(struct proc *p, pid_t pgid, struct pgrp *pgrp, struct session *sess);
   int     enterthispgrp(struct proc *p, struct pgrp *pgrp);
   void    faultin(struct proc *p);
   void    fixjobc(struct proc *p, struct pgrp *pgrp, int entering);
   int     fork1(struct thread *, int, int, struct proc **);
   void    fork_exit(void (*)(void *, struct trapframe *), void *,
               struct trapframe *);
   void    fork_return(struct thread *, struct trapframe *);
   int     inferior(struct proc *p);
   int     leavepgrp(struct proc *p);
   void    mi_switch(void);
   int     p_candebug(struct thread *td, struct proc *p);
   int     p_cansee(struct thread *td, struct proc *p);
   int     p_cansched(struct thread *td, struct proc *p);
   int     p_cansignal(struct thread *td, struct proc *p, int signum);
   struct  pargs *pargs_alloc(int len);
   void    pargs_drop(struct pargs *pa);
   void    pargs_free(struct pargs *pa);
   void    pargs_hold(struct pargs *pa);
   void    procinit(void);
   void    threadinit(void);
   void    proc_linkup(struct proc *p, struct ksegrp *kg,
               struct kse *ke, struct thread *td);
   void    proc_reparent(struct proc *child, struct proc *newparent);
   int     securelevel_ge(struct ucred *cr, int level);
   int     securelevel_gt(struct ucred *cr, int level);
   void    setrunnable(struct thread *);
   void    setrunqueue(struct thread *);
   void    setsugid(struct proc *p);
   int     sigonstack(size_t sp);
   void    sleepinit(void);
   void    stopevent(struct proc *, u_int, u_int);
   void    cpu_idle(void);
   extern  void (*cpu_idle_hook)(void);    /* Hook to machdep CPU idler. */
   void    cpu_switch(struct thread *old, struct thread *new);
   void    cpu_throw(struct thread *old, struct thread *new) __dead2;
   void    unsleep(struct thread *);
   void    userret(struct thread *, struct trapframe *, u_int);
   
   void    cpu_exit(struct thread *);
   void    cpu_sched_exit(struct thread *);
   void    exit1(struct thread *, int) __dead2;
   void    cpu_fork(struct thread *, struct proc *, struct thread *, int);
   void    cpu_set_fork_handler(struct thread *, void (*)(void *), void *);
   
   /* New in KSE. */
   struct  ksegrp *ksegrp_alloc(void);
   void    ksegrp_free(struct ksegrp *kg);
   void    ksegrp_stash(struct ksegrp *kg);
   struct  kse *kse_alloc(void);
   void    kse_free(struct kse *ke);
   void    kse_stash(struct kse *ke);
   void    cpu_set_upcall(struct thread *td, struct thread *td0);
   void    cpu_set_upcall_kse(struct thread *td, struct kse_upcall *ku);
   void    cpu_thread_clean(struct thread *);
   void    cpu_thread_exit(struct thread *);
   void    cpu_thread_setup(struct thread *td);
   void    cpu_thread_siginfo(int sig, u_long code, siginfo_t *si);
   void    cpu_thread_swapin(struct thread *);
   void    cpu_thread_swapout(struct thread *);
   void    kse_reassign(struct kse *ke);
   void    kse_link(struct kse *ke, struct ksegrp *kg);
   void    kse_unlink(struct kse *ke);
   void    ksegrp_link(struct ksegrp *kg, struct proc *p);
   void    ksegrp_unlink(struct ksegrp *kg);
   void    thread_signal_add(struct thread *td, int sig);
   struct  thread *thread_alloc(void);
   void    thread_exit(void) __dead2;
   int     thread_export_context(struct thread *td, int willexit);
   void    thread_free(struct thread *td);
   void    thread_link(struct thread *td, struct ksegrp *kg);
   void    thread_reap(void);
   struct thread *thread_schedule_upcall(struct thread *td, struct kse_upcall *ku);
   int     thread_single(int how);
   #define SINGLE_NO_EXIT 0                        /* values for 'how' */
   #define SINGLE_EXIT 1
   void    thread_single_end(void);
   void    thread_stash(struct thread *td);
   int     thread_suspend_check(int how);
   void    thread_suspend_one(struct thread *td);
   void    thread_unlink(struct thread *td);
   void    thread_unsuspend(struct proc *p);
   void    thread_unsuspend_one(struct thread *td);
   int     thread_userret(struct thread *td, struct trapframe *frame);
   void    thread_user_enter(struct proc *p, struct thread *td);
   void    thread_wait(struct proc *p);
   int     thread_statclock(int user);
   struct kse_upcall *upcall_alloc(void);
   void    upcall_free(struct kse_upcall *ku);
   void    upcall_link(struct kse_upcall *ku, struct ksegrp *kg);
   void    upcall_unlink(struct kse_upcall *ku);
   void    upcall_remove(struct thread *td);
   void    upcall_stash(struct kse_upcall *ke);
   void    thread_sanity_check(struct thread *td, char *);
   void    thread_stopped(struct proc *p);
   void    thread_switchout(struct thread *td);
   void    thr_exit1(void);
   #endif  /* _KERNEL */
   
   #endif  /* !_SYS_PROC_H_ */

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