The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_kthread.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/cpuset.h>
   35 #include <sys/kthread.h>
   36 #include <sys/lock.h>
   37 #include <sys/mutex.h>
   38 #include <sys/proc.h>
   39 #include <sys/resourcevar.h>
   40 #include <sys/rwlock.h>
   41 #include <sys/signalvar.h>
   42 #include <sys/sysent.h>
   43 #include <sys/sx.h>
   44 #include <sys/umtx.h>
   45 #include <sys/unistd.h>
   46 #include <sys/wait.h>
   47 #include <sys/sched.h>
   48 #include <sys/tslog.h>
   49 #include <vm/vm.h>
   50 #include <vm/vm_extern.h>
   51 
   52 #include <machine/stdarg.h>
   53 
   54 /*
   55  * Start a kernel process.  This is called after a fork() call in
   56  * mi_startup() in the file kern/init_main.c.
   57  *
   58  * This function is used to start "internal" daemons and intended
   59  * to be called from SYSINIT().
   60  */
   61 void
   62 kproc_start(const void *udata)
   63 {
   64         const struct kproc_desc *kp = udata;
   65         int error;
   66 
   67         error = kproc_create((void (*)(void *))kp->func, NULL,
   68                     kp->global_procpp, 0, 0, "%s", kp->arg0);
   69         if (error)
   70                 panic("kproc_start: %s: error %d", kp->arg0, error);
   71 }
   72 
   73 /*
   74  * Create a kernel process/thread/whatever.  It shares its address space
   75  * with proc0 - ie: kernel only.
   76  *
   77  * func is the function to start.
   78  * arg is the parameter to pass to function on first startup.
   79  * newpp is the return value pointing to the thread's struct proc.
   80  * flags are flags to fork1 (in unistd.h)
   81  * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
   82  */
   83 int
   84 kproc_create(void (*func)(void *), void *arg,
   85     struct proc **newpp, int flags, int pages, const char *fmt, ...)
   86 {
   87         struct fork_req fr;
   88         int error;
   89         va_list ap;
   90         struct thread *td;
   91         struct proc *p2;
   92 
   93         if (!proc0.p_stats)
   94                 panic("kproc_create called too soon");
   95 
   96         bzero(&fr, sizeof(fr));
   97         fr.fr_flags = RFMEM | RFFDG | RFPROC | RFSTOPPED | flags;
   98         fr.fr_flags2 = FR2_KPROC;
   99         fr.fr_pages = pages;
  100         fr.fr_procp = &p2;
  101         error = fork1(&thread0, &fr);
  102         if (error)
  103                 return error;
  104 
  105         /* save a global descriptor, if desired */
  106         if (newpp != NULL)
  107                 *newpp = 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         td = FIRST_THREAD_IN_PROC(p2);
  114         va_start(ap, fmt);
  115         vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
  116         va_end(ap);
  117 #ifdef KTR
  118         sched_clear_tdname(td);
  119 #endif
  120         TSTHREAD(td, td->td_name);
  121 #ifdef HWPMC_HOOKS
  122         if (PMC_SYSTEM_SAMPLING_ACTIVE()) {
  123                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_PROC_CREATE_LOG, p2);
  124                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_CREATE_LOG, NULL);
  125         }
  126 #endif
  127 
  128         /* call the processes' main()... */
  129         cpu_fork_kthread_handler(td, func, arg);
  130 
  131         /* Avoid inheriting affinity from a random parent. */
  132         cpuset_kernthread(td);
  133         thread_lock(td);
  134         TD_SET_CAN_RUN(td);
  135         sched_prio(td, PVM);
  136         sched_user_prio(td, PUSER);
  137 
  138         /* Delay putting it on the run queue until now. */
  139         if (!(flags & RFSTOPPED))
  140                 sched_add(td, SRQ_BORING); 
  141         else
  142                 thread_unlock(td);
  143 
  144         return 0;
  145 }
  146 
  147 void
  148 kproc_exit(int ecode)
  149 {
  150         struct thread *td;
  151         struct proc *p;
  152 
  153         td = curthread;
  154         p = td->td_proc;
  155 
  156         /*
  157          * Reparent curthread from proc0 to init so that the zombie
  158          * is harvested.
  159          */
  160         sx_xlock(&proctree_lock);
  161         PROC_LOCK(p);
  162         proc_reparent(p, initproc, true);
  163         PROC_UNLOCK(p);
  164         sx_xunlock(&proctree_lock);
  165 
  166         /*
  167          * Wakeup anyone waiting for us to exit.
  168          */
  169         wakeup(p);
  170 
  171         /* Buh-bye! */
  172         exit1(td, ecode, 0);
  173 }
  174 
  175 /*
  176  * Advise a kernel process to suspend (or resume) in its main loop.
  177  * Participation is voluntary.
  178  */
  179 int
  180 kproc_suspend(struct proc *p, int timo)
  181 {
  182         /*
  183          * Make sure this is indeed a system process and we can safely
  184          * use the p_siglist field.
  185          */
  186         PROC_LOCK(p);
  187         if ((p->p_flag & P_KPROC) == 0) {
  188                 PROC_UNLOCK(p);
  189                 return (EINVAL);
  190         }
  191         SIGADDSET(p->p_siglist, SIGSTOP);
  192         wakeup(p);
  193         return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
  194 }
  195 
  196 int
  197 kproc_resume(struct proc *p)
  198 {
  199         /*
  200          * Make sure this is indeed a system process and we can safely
  201          * use the p_siglist field.
  202          */
  203         PROC_LOCK(p);
  204         if ((p->p_flag & P_KPROC) == 0) {
  205                 PROC_UNLOCK(p);
  206                 return (EINVAL);
  207         }
  208         SIGDELSET(p->p_siglist, SIGSTOP);
  209         PROC_UNLOCK(p);
  210         wakeup(&p->p_siglist);
  211         return (0);
  212 }
  213 
  214 void
  215 kproc_suspend_check(struct proc *p)
  216 {
  217         PROC_LOCK(p);
  218         while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
  219                 wakeup(&p->p_siglist);
  220                 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
  221         }
  222         PROC_UNLOCK(p);
  223 }
  224 
  225 /*
  226  * Start a kernel thread.  
  227  *
  228  * This function is used to start "internal" daemons and intended
  229  * to be called from SYSINIT().
  230  */
  231 
  232 void
  233 kthread_start(const void *udata)
  234 {
  235         const struct kthread_desc       *kp = udata;
  236         int error;
  237 
  238         error = kthread_add((void (*)(void *))kp->func, NULL,
  239                     NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
  240         if (error)
  241                 panic("kthread_start: %s: error %d", kp->arg0, error);
  242 }
  243 
  244 /*
  245  * Create a kernel thread.  It shares its address space
  246  * with proc0 - ie: kernel only.
  247  *
  248  * func is the function to start.
  249  * arg is the parameter to pass to function on first startup.
  250  * newtdp is the return value pointing to the thread's struct thread.
  251  *  ** XXX fix this --> flags are flags to fork1 (in unistd.h) 
  252  * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
  253  */
  254 int
  255 kthread_add(void (*func)(void *), void *arg, struct proc *p,
  256     struct thread **newtdp, int flags, int pages, const char *fmt, ...)
  257 {
  258         va_list ap;
  259         struct thread *newtd, *oldtd;
  260 
  261         if (!proc0.p_stats)
  262                 panic("kthread_add called too soon");
  263 
  264         /* If no process supplied, put it on proc0 */
  265         if (p == NULL)
  266                 p = &proc0;
  267 
  268         /* Initialize our new td  */
  269         newtd = thread_alloc(pages);
  270         if (newtd == NULL)
  271                 return (ENOMEM);
  272 
  273         PROC_LOCK(p);
  274         oldtd = FIRST_THREAD_IN_PROC(p);
  275 
  276         bzero(&newtd->td_startzero,
  277             __rangeof(struct thread, td_startzero, td_endzero));
  278         bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
  279             __rangeof(struct thread, td_startcopy, td_endcopy));
  280 
  281         /* set up arg0 for 'ps', et al */
  282         va_start(ap, fmt);
  283         vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
  284         va_end(ap);
  285 
  286         TSTHREAD(newtd, newtd->td_name);
  287 
  288         newtd->td_proc = p;  /* needed for cpu_copy_thread */
  289         newtd->td_pflags |= TDP_KTHREAD;
  290 
  291         /* might be further optimized for kthread */
  292         cpu_copy_thread(newtd, oldtd);
  293 
  294         /* put the designated function(arg) as the resume context */
  295         cpu_fork_kthread_handler(newtd, func, arg);
  296 
  297         thread_cow_get_proc(newtd, p);
  298 
  299         /* this code almost the same as create_thread() in kern_thr.c */
  300         p->p_flag |= P_HADTHREADS;
  301         thread_link(newtd, p);
  302         thread_lock(oldtd);
  303         /* let the scheduler know about these things. */
  304         sched_fork_thread(oldtd, newtd);
  305         TD_SET_CAN_RUN(newtd);
  306         thread_unlock(oldtd);
  307         PROC_UNLOCK(p);
  308 
  309         tidhash_add(newtd);
  310 
  311         /* Avoid inheriting affinity from a random parent. */
  312         cpuset_kernthread(newtd);
  313 #ifdef HWPMC_HOOKS
  314         if (PMC_SYSTEM_SAMPLING_ACTIVE())
  315                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_CREATE_LOG, NULL);
  316 #endif
  317         /* Delay putting it on the run queue until now. */
  318         if (!(flags & RFSTOPPED)) {
  319                 thread_lock(newtd);
  320                 sched_add(newtd, SRQ_BORING); 
  321         }
  322         if (newtdp)
  323                 *newtdp = newtd;
  324         return 0;
  325 }
  326 
  327 void
  328 kthread_exit(void)
  329 {
  330         struct proc *p;
  331         struct thread *td;
  332 
  333         td = curthread;
  334         p = td->td_proc;
  335 
  336 #ifdef HWPMC_HOOKS
  337         if (PMC_SYSTEM_SAMPLING_ACTIVE())
  338                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
  339 #endif
  340         /* A module may be waiting for us to exit. */
  341         wakeup(td);
  342 
  343         /*
  344          * The last exiting thread in a kernel process must tear down
  345          * the whole process.
  346          */
  347         PROC_LOCK(p);
  348         if (p->p_numthreads == 1) {
  349                 PROC_UNLOCK(p);
  350                 kproc_exit(0);
  351         }
  352 
  353         if (p->p_sysent->sv_ontdexit != NULL)
  354                 p->p_sysent->sv_ontdexit(td);
  355 
  356         tidhash_remove(td);
  357         umtx_thread_exit(td);
  358         tdsigcleanup(td);
  359         PROC_SLOCK(p);
  360         thread_exit();
  361 }
  362 
  363 /*
  364  * Advise a kernel process to suspend (or resume) in its main loop.
  365  * Participation is voluntary.
  366  */
  367 int
  368 kthread_suspend(struct thread *td, int timo)
  369 {
  370         struct proc *p;
  371 
  372         p = td->td_proc;
  373 
  374         /*
  375          * td_pflags should not be read by any thread other than
  376          * curthread, but as long as this flag is invariant during the
  377          * thread's lifetime, it is OK to check its state.
  378          */
  379         if ((td->td_pflags & TDP_KTHREAD) == 0)
  380                 return (EINVAL);
  381 
  382         /*
  383          * The caller of the primitive should have already checked that the
  384          * thread is up and running, thus not being blocked by other
  385          * conditions.
  386          */
  387         PROC_LOCK(p);
  388         thread_lock(td);
  389         td->td_flags |= TDF_KTH_SUSP;
  390         thread_unlock(td);
  391         return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
  392             timo));
  393 }
  394 
  395 /*
  396  * Resume a thread previously put asleep with kthread_suspend().
  397  */
  398 int
  399 kthread_resume(struct thread *td)
  400 {
  401         struct proc *p;
  402 
  403         p = td->td_proc;
  404 
  405         /*
  406          * td_pflags should not be read by any thread other than
  407          * curthread, but as long as this flag is invariant during the
  408          * thread's lifetime, it is OK to check its state.
  409          */
  410         if ((td->td_pflags & TDP_KTHREAD) == 0)
  411                 return (EINVAL);
  412 
  413         PROC_LOCK(p);
  414         thread_lock(td);
  415         td->td_flags &= ~TDF_KTH_SUSP;
  416         thread_unlock(td);
  417         wakeup(&td->td_flags);
  418         PROC_UNLOCK(p);
  419         return (0);
  420 }
  421 
  422 /*
  423  * Used by the thread to poll as to whether it should yield/sleep
  424  * and notify the caller that is has happened.
  425  */
  426 void
  427 kthread_suspend_check(void)
  428 {
  429         struct proc *p;
  430         struct thread *td;
  431 
  432         td = curthread;
  433         p = td->td_proc;
  434 
  435         if ((td->td_pflags & TDP_KTHREAD) == 0)
  436                 panic("%s: curthread is not a valid kthread", __func__);
  437 
  438         /*
  439          * Setting the TDF_KTH_SUSP flag is protected by process lock.
  440          *
  441          * Do an unlocked read first to avoid serializing with all other threads
  442          * in the common case of not suspending.
  443          */
  444         if ((td->td_flags & TDF_KTH_SUSP) == 0)
  445                 return;
  446         PROC_LOCK(p);
  447         while ((td->td_flags & TDF_KTH_SUSP) != 0) {
  448                 wakeup(&td->td_flags);
  449                 msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
  450         }
  451         PROC_UNLOCK(p);
  452 }
  453 
  454 int
  455 kproc_kthread_add(void (*func)(void *), void *arg,
  456             struct proc **procptr, struct thread **tdptr,
  457             int flags, int pages, const char *procname, const char *fmt, ...) 
  458 {
  459         int error;
  460         va_list ap;
  461         char buf[100];
  462         struct thread *td;
  463 
  464         if (*procptr == NULL) {
  465                 error = kproc_create(func, arg,
  466                         procptr, flags, pages, "%s", procname);
  467                 if (error)
  468                         return (error);
  469                 td = FIRST_THREAD_IN_PROC(*procptr);
  470                 if (tdptr)
  471                         *tdptr = td;
  472                 va_start(ap, fmt);
  473                 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
  474                 va_end(ap);
  475 #ifdef KTR
  476                 sched_clear_tdname(td);
  477 #endif
  478                 return (0); 
  479         }
  480         va_start(ap, fmt);
  481         vsnprintf(buf, sizeof(buf), fmt, ap);
  482         va_end(ap);
  483         error = kthread_add(func, arg, *procptr,
  484                     tdptr, flags, pages, "%s", buf);
  485         return (error);
  486 }

Cache object: ac0bcddfb7f377b666e02000804a9d66


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