kern_kthread.c

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    1 /*-
    2  * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/9.0/sys/kern/kern_kthread.c 224987 2011-08-18 22:51:30Z jonathan $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/kthread.h>
   33 #include <sys/lock.h>
   34 #include <sys/mutex.h>
   35 #include <sys/proc.h>
   36 #include <sys/resourcevar.h>
   37 #include <sys/rwlock.h>
   38 #include <sys/signalvar.h>
   39 #include <sys/sx.h>
   40 #include <sys/unistd.h>
   41 #include <sys/wait.h>
   42 #include <sys/sched.h>
   43 #include <vm/vm.h>
   44 #include <vm/vm_extern.h>
   45 
   46 #include <machine/stdarg.h>
   47 
   48 /*
   49  * Start a kernel process.  This is called after a fork() call in
   50  * mi_startup() in the file kern/init_main.c.
   51  *
   52  * This function is used to start "internal" daemons and intended
   53  * to be called from SYSINIT().
   54  */
   55 void
   56 kproc_start(udata)
   57         const void *udata;
   58 {
   59         const struct kproc_desc *kp = udata;
   60         int error;
   61 
   62         error = kproc_create((void (*)(void *))kp->func, NULL,
   63                     kp->global_procpp, 0, 0, "%s", kp->arg0);
   64         if (error)
   65                 panic("kproc_start: %s: error %d", kp->arg0, error);
   66 }
   67 
   68 /*
   69  * Create a kernel process/thread/whatever.  It shares its address space
   70  * with proc0 - ie: kernel only.
   71  *
   72  * func is the function to start.
   73  * arg is the parameter to pass to function on first startup.
   74  * newpp is the return value pointing to the thread's struct proc.
   75  * flags are flags to fork1 (in unistd.h)
   76  * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
   77  */
   78 int
   79 kproc_create(void (*func)(void *), void *arg,
   80     struct proc **newpp, int flags, int pages, const char *fmt, ...)
   81 {
   82         int error;
   83         va_list ap;
   84         struct thread *td;
   85         struct proc *p2;
   86 
   87         if (!proc0.p_stats)
   88                 panic("kproc_create called too soon");
   89 
   90         error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags,
   91             pages, &p2, NULL, 0);
   92         if (error)
   93                 return error;
   94 
   95         /* save a global descriptor, if desired */
   96         if (newpp != NULL)
   97                 *newpp = p2;
   98 
   99         /* this is a non-swapped system process */
  100         PROC_LOCK(p2);
  101         td = FIRST_THREAD_IN_PROC(p2);
  102         p2->p_flag |= P_SYSTEM | P_KTHREAD;
  103         td->td_pflags |= TDP_KTHREAD;
  104         mtx_lock(&p2->p_sigacts->ps_mtx);
  105         p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
  106         mtx_unlock(&p2->p_sigacts->ps_mtx);
  107         PROC_UNLOCK(p2);
  108 
  109         /* set up arg0 for 'ps', et al */
  110         va_start(ap, fmt);
  111         vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
  112         va_end(ap);
  113         /* set up arg0 for 'ps', et al */
  114         va_start(ap, fmt);
  115         vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
  116         va_end(ap);
  117 
  118         /* call the processes' main()... */
  119         cpu_set_fork_handler(td, func, arg);
  120         thread_lock(td);
  121         TD_SET_CAN_RUN(td);
  122         sched_prio(td, PVM);
  123         sched_user_prio(td, PUSER);
  124 
  125         /* Delay putting it on the run queue until now. */
  126         if (!(flags & RFSTOPPED))
  127                 sched_add(td, SRQ_BORING); 
  128         thread_unlock(td);
  129 
  130         return 0;
  131 }
  132 
  133 void
  134 kproc_exit(int ecode)
  135 {
  136         struct thread *td;
  137         struct proc *p;
  138 
  139         td = curthread;
  140         p = td->td_proc;
  141 
  142         /*
  143          * Reparent curthread from proc0 to init so that the zombie
  144          * is harvested.
  145          */
  146         sx_xlock(&proctree_lock);
  147         PROC_LOCK(p);
  148         proc_reparent(p, initproc);
  149         PROC_UNLOCK(p);
  150         sx_xunlock(&proctree_lock);
  151 
  152         /*
  153          * Wakeup anyone waiting for us to exit.
  154          */
  155         wakeup(p);
  156 
  157         /* Buh-bye! */
  158         exit1(td, W_EXITCODE(ecode, 0));
  159 }
  160 
  161 /*
  162  * Advise a kernel process to suspend (or resume) in its main loop.
  163  * Participation is voluntary.
  164  */
  165 int
  166 kproc_suspend(struct proc *p, int timo)
  167 {
  168         /*
  169          * Make sure this is indeed a system process and we can safely
  170          * use the p_siglist field.
  171          */
  172         PROC_LOCK(p);
  173         if ((p->p_flag & P_KTHREAD) == 0) {
  174                 PROC_UNLOCK(p);
  175                 return (EINVAL);
  176         }
  177         SIGADDSET(p->p_siglist, SIGSTOP);
  178         wakeup(p);
  179         return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
  180 }
  181 
  182 int
  183 kproc_resume(struct proc *p)
  184 {
  185         /*
  186          * Make sure this is indeed a system process and we can safely
  187          * use the p_siglist field.
  188          */
  189         PROC_LOCK(p);
  190         if ((p->p_flag & P_KTHREAD) == 0) {
  191                 PROC_UNLOCK(p);
  192                 return (EINVAL);
  193         }
  194         SIGDELSET(p->p_siglist, SIGSTOP);
  195         PROC_UNLOCK(p);
  196         wakeup(&p->p_siglist);
  197         return (0);
  198 }
  199 
  200 void
  201 kproc_suspend_check(struct proc *p)
  202 {
  203         PROC_LOCK(p);
  204         while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
  205                 wakeup(&p->p_siglist);
  206                 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
  207         }
  208         PROC_UNLOCK(p);
  209 }
  210 
  211 
  212 /*
  213  * Start a kernel thread.  
  214  *
  215  * This function is used to start "internal" daemons and intended
  216  * to be called from SYSINIT().
  217  */
  218 
  219 void
  220 kthread_start(udata)
  221         const void *udata;
  222 {
  223         const struct kthread_desc       *kp = udata;
  224         int error;
  225 
  226         error = kthread_add((void (*)(void *))kp->func, NULL,
  227                     NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
  228         if (error)
  229                 panic("kthread_start: %s: error %d", kp->arg0, error);
  230 }
  231 
  232 /*
  233  * Create a kernel thread.  It shares its address space
  234  * with proc0 - ie: kernel only.
  235  *
  236  * func is the function to start.
  237  * arg is the parameter to pass to function on first startup.
  238  * newtdp is the return value pointing to the thread's struct thread.
  239  *  ** XXX fix this --> flags are flags to fork1 (in unistd.h) 
  240  * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
  241  */
  242 int
  243 kthread_add(void (*func)(void *), void *arg, struct proc *p,
  244     struct thread **newtdp, int flags, int pages, const char *fmt, ...)
  245 {
  246         va_list ap;
  247         struct thread *newtd, *oldtd;
  248 
  249         if (!proc0.p_stats)
  250                 panic("kthread_add called too soon");
  251 
  252         /* If no process supplied, put it on proc0 */
  253         if (p == NULL) {
  254                 p = &proc0;
  255                 oldtd = &thread0;
  256         } else {
  257                 oldtd = FIRST_THREAD_IN_PROC(p);
  258         }
  259 
  260         /* Initialize our new td  */
  261         newtd = thread_alloc(pages);
  262         if (newtd == NULL)
  263                 return (ENOMEM);
  264 
  265         bzero(&newtd->td_startzero,
  266             __rangeof(struct thread, td_startzero, td_endzero));
  267 /* XXX check if we should zero. */
  268         bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
  269             __rangeof(struct thread, td_startcopy, td_endcopy));
  270 
  271         /* set up arg0 for 'ps', et al */
  272         va_start(ap, fmt);
  273         vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
  274         va_end(ap);
  275 
  276         newtd->td_proc = p;  /* needed for cpu_set_upcall */
  277 
  278         /* XXX optimise this probably? */
  279         /* On x86 (and probably the others too) it is way too full of junk */
  280         /* Needs a better name */
  281         cpu_set_upcall(newtd, oldtd);
  282         /* put the designated function(arg) as the resume context */
  283         cpu_set_fork_handler(newtd, func, arg);
  284 
  285         newtd->td_pflags |= TDP_KTHREAD;
  286         newtd->td_ucred = crhold(p->p_ucred);
  287 
  288         /* this code almost the same as create_thread() in kern_thr.c */
  289         PROC_LOCK(p);
  290         p->p_flag |= P_HADTHREADS;
  291         newtd->td_sigmask = oldtd->td_sigmask; /* XXX dubious */
  292         thread_link(newtd, p);
  293         thread_lock(oldtd);
  294         /* let the scheduler know about these things. */
  295         sched_fork_thread(oldtd, newtd);
  296         TD_SET_CAN_RUN(newtd);
  297         thread_unlock(oldtd);
  298         PROC_UNLOCK(p);
  299 
  300         tidhash_add(newtd);
  301 
  302         /* Delay putting it on the run queue until now. */
  303         if (!(flags & RFSTOPPED)) {
  304                 thread_lock(newtd);
  305                 sched_add(newtd, SRQ_BORING); 
  306                 thread_unlock(newtd);
  307         }
  308         if (newtdp)
  309                 *newtdp = newtd;
  310         return 0;
  311 }
  312 
  313 void
  314 kthread_exit(void)
  315 {
  316         struct proc *p;
  317 
  318         p = curthread->td_proc;
  319 
  320         /* A module may be waiting for us to exit. */
  321         wakeup(curthread);
  322 
  323         /*
  324          * The last exiting thread in a kernel process must tear down
  325          * the whole process.
  326          */
  327         rw_wlock(&tidhash_lock);
  328         PROC_LOCK(p);
  329         if (p->p_numthreads == 1) {
  330                 PROC_UNLOCK(p);
  331                 rw_wunlock(&tidhash_lock);
  332                 kproc_exit(0);
  333         }
  334         LIST_REMOVE(curthread, td_hash);
  335         rw_wunlock(&tidhash_lock);
  336         PROC_SLOCK(p);
  337         thread_exit();
  338 }
  339 
  340 /*
  341  * Advise a kernel process to suspend (or resume) in its main loop.
  342  * Participation is voluntary.
  343  */
  344 int
  345 kthread_suspend(struct thread *td, int timo)
  346 {
  347         struct proc *p;
  348 
  349         p = td->td_proc;
  350 
  351         /*
  352          * td_pflags should not be read by any thread other than
  353          * curthread, but as long as this flag is invariant during the
  354          * thread's lifetime, it is OK to check its state.
  355          */
  356         if ((td->td_pflags & TDP_KTHREAD) == 0)
  357                 return (EINVAL);
  358 
  359         /*
  360          * The caller of the primitive should have already checked that the
  361          * thread is up and running, thus not being blocked by other
  362          * conditions.
  363          */
  364         PROC_LOCK(p);
  365         thread_lock(td);
  366         td->td_flags |= TDF_KTH_SUSP;
  367         thread_unlock(td);
  368         return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
  369             timo));
  370 }
  371 
  372 /*
  373  * Resume a thread previously put asleep with kthread_suspend().
  374  */
  375 int
  376 kthread_resume(struct thread *td)
  377 {
  378         struct proc *p;
  379 
  380         p = td->td_proc;
  381 
  382         /*
  383          * td_pflags should not be read by any thread other than
  384          * curthread, but as long as this flag is invariant during the
  385          * thread's lifetime, it is OK to check its state.
  386          */
  387         if ((td->td_pflags & TDP_KTHREAD) == 0)
  388                 return (EINVAL);
  389 
  390         PROC_LOCK(p);
  391         thread_lock(td);
  392         td->td_flags &= ~TDF_KTH_SUSP;
  393         thread_unlock(td);
  394         wakeup(&td->td_flags);
  395         PROC_UNLOCK(p);
  396         return (0);
  397 }
  398 
  399 /*
  400  * Used by the thread to poll as to whether it should yield/sleep
  401  * and notify the caller that is has happened.
  402  */
  403 void
  404 kthread_suspend_check()
  405 {
  406         struct proc *p;
  407         struct thread *td;
  408 
  409         td = curthread;
  410         p = td->td_proc;
  411 
  412         if ((td->td_pflags & TDP_KTHREAD) == 0)
  413                 panic("%s: curthread is not a valid kthread", __func__);
  414 
  415         /*
  416          * As long as the double-lock protection is used when accessing the
  417          * TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex
  418          * is fine.
  419          */
  420         PROC_LOCK(p);
  421         while (td->td_flags & TDF_KTH_SUSP) {
  422                 wakeup(&td->td_flags);
  423                 msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
  424         }
  425         PROC_UNLOCK(p);
  426 }
  427 
  428 int
  429 kproc_kthread_add(void (*func)(void *), void *arg,
  430             struct proc **procptr, struct thread **tdptr,
  431             int flags, int pages, const char *procname, const char *fmt, ...) 
  432 {
  433         int error;
  434         va_list ap;
  435         char buf[100];
  436         struct thread *td;
  437 
  438         if (*procptr == 0) {
  439                 error = kproc_create(func, arg,
  440                         procptr, flags, pages, "%s", procname);
  441                 if (error)
  442                         return (error);
  443                 td = FIRST_THREAD_IN_PROC(*procptr);
  444                 if (tdptr)
  445                         *tdptr = td;
  446                 va_start(ap, fmt);
  447                 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
  448                 va_end(ap);
  449                 return (0); 
  450         }
  451         va_start(ap, fmt);
  452         vsnprintf(buf, sizeof(buf), fmt, ap);
  453         va_end(ap);
  454         error = kthread_add(func, arg, *procptr,
  455                     tdptr, flags, pages, "%s", buf);
  456         return (error);
  457 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_kthread.c

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