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: releng/12.0/sys/kern/kern_kthread.c 334647 2018-06-05 04:26:40Z mmacy $");
   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/sx.h>
   43 #include <sys/umtx.h>
   44 #include <sys/unistd.h>
   45 #include <sys/wait.h>
   46 #include <sys/sched.h>
   47 #include <sys/tslog.h>
   48 #include <vm/vm.h>
   49 #include <vm/vm_extern.h>
   50 
   51 #include <machine/stdarg.h>
   52 
   53 /*
   54  * Start a kernel process.  This is called after a fork() call in
   55  * mi_startup() in the file kern/init_main.c.
   56  *
   57  * This function is used to start "internal" daemons and intended
   58  * to be called from SYSINIT().
   59  */
   60 void
   61 kproc_start(const void *udata)
   62 {
   63         const struct kproc_desc *kp = udata;
   64         int error;
   65 
   66         error = kproc_create((void (*)(void *))kp->func, NULL,
   67                     kp->global_procpp, 0, 0, "%s", kp->arg0);
   68         if (error)
   69                 panic("kproc_start: %s: error %d", kp->arg0, error);
   70 }
   71 
   72 /*
   73  * Create a kernel process/thread/whatever.  It shares its address space
   74  * with proc0 - ie: kernel only.
   75  *
   76  * func is the function to start.
   77  * arg is the parameter to pass to function on first startup.
   78  * newpp is the return value pointing to the thread's struct proc.
   79  * flags are flags to fork1 (in unistd.h)
   80  * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
   81  */
   82 int
   83 kproc_create(void (*func)(void *), void *arg,
   84     struct proc **newpp, int flags, int pages, const char *fmt, ...)
   85 {
   86         struct fork_req fr;
   87         int error;
   88         va_list ap;
   89         struct thread *td;
   90         struct proc *p2;
   91 
   92         if (!proc0.p_stats)
   93                 panic("kproc_create called too soon");
   94 
   95         bzero(&fr, sizeof(fr));
   96         fr.fr_flags = RFMEM | RFFDG | RFPROC | RFSTOPPED | flags;
   97         fr.fr_pages = pages;
   98         fr.fr_procp = &p2;
   99         error = fork1(&thread0, &fr);
  100         if (error)
  101                 return error;
  102 
  103         /* save a global descriptor, if desired */
  104         if (newpp != NULL)
  105                 *newpp = p2;
  106 
  107         /* this is a non-swapped system process */
  108         PROC_LOCK(p2);
  109         td = FIRST_THREAD_IN_PROC(p2);
  110         p2->p_flag |= P_SYSTEM | P_KPROC;
  111         td->td_pflags |= TDP_KTHREAD;
  112         mtx_lock(&p2->p_sigacts->ps_mtx);
  113         p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
  114         mtx_unlock(&p2->p_sigacts->ps_mtx);
  115         PROC_UNLOCK(p2);
  116 
  117         /* set up arg0 for 'ps', et al */
  118         va_start(ap, fmt);
  119         vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
  120         va_end(ap);
  121         /* set up arg0 for 'ps', et al */
  122         va_start(ap, fmt);
  123         vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
  124         va_end(ap);
  125 #ifdef KTR
  126         sched_clear_tdname(td);
  127 #endif
  128         TSTHREAD(td, td->td_name);
  129 #ifdef HWPMC_HOOKS
  130         if (PMC_SYSTEM_SAMPLING_ACTIVE()) {
  131                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_PROC_CREATE_LOG, p2);
  132                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_CREATE_LOG, NULL);
  133         }
  134 #endif
  135 
  136         /* call the processes' main()... */
  137         cpu_fork_kthread_handler(td, func, arg);
  138 
  139         /* Avoid inheriting affinity from a random parent. */
  140         cpuset_kernthread(td);
  141         thread_lock(td);
  142         TD_SET_CAN_RUN(td);
  143         sched_prio(td, PVM);
  144         sched_user_prio(td, PUSER);
  145 
  146         /* Delay putting it on the run queue until now. */
  147         if (!(flags & RFSTOPPED))
  148                 sched_add(td, SRQ_BORING); 
  149         thread_unlock(td);
  150 
  151         return 0;
  152 }
  153 
  154 void
  155 kproc_exit(int ecode)
  156 {
  157         struct thread *td;
  158         struct proc *p;
  159 
  160         td = curthread;
  161         p = td->td_proc;
  162 
  163         /*
  164          * Reparent curthread from proc0 to init so that the zombie
  165          * is harvested.
  166          */
  167         sx_xlock(&proctree_lock);
  168         PROC_LOCK(p);
  169         proc_reparent(p, initproc);
  170         PROC_UNLOCK(p);
  171         sx_xunlock(&proctree_lock);
  172 
  173         /*
  174          * Wakeup anyone waiting for us to exit.
  175          */
  176         wakeup(p);
  177 
  178         /* Buh-bye! */
  179         exit1(td, ecode, 0);
  180 }
  181 
  182 /*
  183  * Advise a kernel process to suspend (or resume) in its main loop.
  184  * Participation is voluntary.
  185  */
  186 int
  187 kproc_suspend(struct proc *p, int timo)
  188 {
  189         /*
  190          * Make sure this is indeed a system process and we can safely
  191          * use the p_siglist field.
  192          */
  193         PROC_LOCK(p);
  194         if ((p->p_flag & P_KPROC) == 0) {
  195                 PROC_UNLOCK(p);
  196                 return (EINVAL);
  197         }
  198         SIGADDSET(p->p_siglist, SIGSTOP);
  199         wakeup(p);
  200         return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
  201 }
  202 
  203 int
  204 kproc_resume(struct proc *p)
  205 {
  206         /*
  207          * Make sure this is indeed a system process and we can safely
  208          * use the p_siglist field.
  209          */
  210         PROC_LOCK(p);
  211         if ((p->p_flag & P_KPROC) == 0) {
  212                 PROC_UNLOCK(p);
  213                 return (EINVAL);
  214         }
  215         SIGDELSET(p->p_siglist, SIGSTOP);
  216         PROC_UNLOCK(p);
  217         wakeup(&p->p_siglist);
  218         return (0);
  219 }
  220 
  221 void
  222 kproc_suspend_check(struct proc *p)
  223 {
  224         PROC_LOCK(p);
  225         while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
  226                 wakeup(&p->p_siglist);
  227                 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
  228         }
  229         PROC_UNLOCK(p);
  230 }
  231 
  232 
  233 /*
  234  * Start a kernel thread.  
  235  *
  236  * This function is used to start "internal" daemons and intended
  237  * to be called from SYSINIT().
  238  */
  239 
  240 void
  241 kthread_start(const void *udata)
  242 {
  243         const struct kthread_desc       *kp = udata;
  244         int error;
  245 
  246         error = kthread_add((void (*)(void *))kp->func, NULL,
  247                     NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
  248         if (error)
  249                 panic("kthread_start: %s: error %d", kp->arg0, error);
  250 }
  251 
  252 /*
  253  * Create a kernel thread.  It shares its address space
  254  * with proc0 - ie: kernel only.
  255  *
  256  * func is the function to start.
  257  * arg is the parameter to pass to function on first startup.
  258  * newtdp is the return value pointing to the thread's struct thread.
  259  *  ** XXX fix this --> flags are flags to fork1 (in unistd.h) 
  260  * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
  261  */
  262 int
  263 kthread_add(void (*func)(void *), void *arg, struct proc *p,
  264     struct thread **newtdp, int flags, int pages, const char *fmt, ...)
  265 {
  266         va_list ap;
  267         struct thread *newtd, *oldtd;
  268 
  269         if (!proc0.p_stats)
  270                 panic("kthread_add called too soon");
  271 
  272         /* If no process supplied, put it on proc0 */
  273         if (p == NULL)
  274                 p = &proc0;
  275 
  276         /* Initialize our new td  */
  277         newtd = thread_alloc(pages);
  278         if (newtd == NULL)
  279                 return (ENOMEM);
  280 
  281         PROC_LOCK(p);
  282         oldtd = FIRST_THREAD_IN_PROC(p);
  283 
  284         bzero(&newtd->td_startzero,
  285             __rangeof(struct thread, td_startzero, td_endzero));
  286         bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
  287             __rangeof(struct thread, td_startcopy, td_endcopy));
  288 
  289         /* set up arg0 for 'ps', et al */
  290         va_start(ap, fmt);
  291         vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
  292         va_end(ap);
  293 
  294         TSTHREAD(newtd, newtd->td_name);
  295 
  296         newtd->td_proc = p;  /* needed for cpu_copy_thread */
  297         /* might be further optimized for kthread */
  298         cpu_copy_thread(newtd, oldtd);
  299         /* put the designated function(arg) as the resume context */
  300         cpu_fork_kthread_handler(newtd, func, arg);
  301 
  302         newtd->td_pflags |= TDP_KTHREAD;
  303         thread_cow_get_proc(newtd, p);
  304 
  305         /* this code almost the same as create_thread() in kern_thr.c */
  306         p->p_flag |= P_HADTHREADS;
  307         thread_link(newtd, p);
  308         thread_lock(oldtd);
  309         /* let the scheduler know about these things. */
  310         sched_fork_thread(oldtd, newtd);
  311         TD_SET_CAN_RUN(newtd);
  312         thread_unlock(oldtd);
  313         PROC_UNLOCK(p);
  314 
  315         tidhash_add(newtd);
  316 
  317         /* Avoid inheriting affinity from a random parent. */
  318         cpuset_kernthread(newtd);
  319 #ifdef HWPMC_HOOKS
  320         if (PMC_SYSTEM_SAMPLING_ACTIVE())
  321                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_CREATE_LOG, NULL);
  322 #endif
  323         /* Delay putting it on the run queue until now. */
  324         if (!(flags & RFSTOPPED)) {
  325                 thread_lock(newtd);
  326                 sched_add(newtd, SRQ_BORING); 
  327                 thread_unlock(newtd);
  328         }
  329         if (newtdp)
  330                 *newtdp = newtd;
  331         return 0;
  332 }
  333 
  334 void
  335 kthread_exit(void)
  336 {
  337         struct proc *p;
  338         struct thread *td;
  339 
  340         td = curthread;
  341         p = td->td_proc;
  342 
  343 #ifdef HWPMC_HOOKS
  344         if (PMC_SYSTEM_SAMPLING_ACTIVE())
  345                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL);
  346 #endif
  347         /* A module may be waiting for us to exit. */
  348         wakeup(td);
  349 
  350         /*
  351          * The last exiting thread in a kernel process must tear down
  352          * the whole process.
  353          */
  354         rw_wlock(&tidhash_lock);
  355         PROC_LOCK(p);
  356         if (p->p_numthreads == 1) {
  357                 PROC_UNLOCK(p);
  358                 rw_wunlock(&tidhash_lock);
  359                 kproc_exit(0);
  360         }
  361         LIST_REMOVE(td, td_hash);
  362         rw_wunlock(&tidhash_lock);
  363         umtx_thread_exit(td);
  364         tdsigcleanup(td);
  365         PROC_SLOCK(p);
  366         thread_exit();
  367 }
  368 
  369 /*
  370  * Advise a kernel process to suspend (or resume) in its main loop.
  371  * Participation is voluntary.
  372  */
  373 int
  374 kthread_suspend(struct thread *td, int timo)
  375 {
  376         struct proc *p;
  377 
  378         p = td->td_proc;
  379 
  380         /*
  381          * td_pflags should not be read by any thread other than
  382          * curthread, but as long as this flag is invariant during the
  383          * thread's lifetime, it is OK to check its state.
  384          */
  385         if ((td->td_pflags & TDP_KTHREAD) == 0)
  386                 return (EINVAL);
  387 
  388         /*
  389          * The caller of the primitive should have already checked that the
  390          * thread is up and running, thus not being blocked by other
  391          * conditions.
  392          */
  393         PROC_LOCK(p);
  394         thread_lock(td);
  395         td->td_flags |= TDF_KTH_SUSP;
  396         thread_unlock(td);
  397         return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
  398             timo));
  399 }
  400 
  401 /*
  402  * Resume a thread previously put asleep with kthread_suspend().
  403  */
  404 int
  405 kthread_resume(struct thread *td)
  406 {
  407         struct proc *p;
  408 
  409         p = td->td_proc;
  410 
  411         /*
  412          * td_pflags should not be read by any thread other than
  413          * curthread, but as long as this flag is invariant during the
  414          * thread's lifetime, it is OK to check its state.
  415          */
  416         if ((td->td_pflags & TDP_KTHREAD) == 0)
  417                 return (EINVAL);
  418 
  419         PROC_LOCK(p);
  420         thread_lock(td);
  421         td->td_flags &= ~TDF_KTH_SUSP;
  422         thread_unlock(td);
  423         wakeup(&td->td_flags);
  424         PROC_UNLOCK(p);
  425         return (0);
  426 }
  427 
  428 /*
  429  * Used by the thread to poll as to whether it should yield/sleep
  430  * and notify the caller that is has happened.
  431  */
  432 void
  433 kthread_suspend_check(void)
  434 {
  435         struct proc *p;
  436         struct thread *td;
  437 
  438         td = curthread;
  439         p = td->td_proc;
  440 
  441         if ((td->td_pflags & TDP_KTHREAD) == 0)
  442                 panic("%s: curthread is not a valid kthread", __func__);
  443 
  444         /*
  445          * As long as the double-lock protection is used when accessing the
  446          * TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex
  447          * is fine.
  448          */
  449         PROC_LOCK(p);
  450         while (td->td_flags & TDF_KTH_SUSP) {
  451                 wakeup(&td->td_flags);
  452                 msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
  453         }
  454         PROC_UNLOCK(p);
  455 }
  456 
  457 int
  458 kproc_kthread_add(void (*func)(void *), void *arg,
  459             struct proc **procptr, struct thread **tdptr,
  460             int flags, int pages, const char *procname, const char *fmt, ...) 
  461 {
  462         int error;
  463         va_list ap;
  464         char buf[100];
  465         struct thread *td;
  466 
  467         if (*procptr == NULL) {
  468                 error = kproc_create(func, arg,
  469                         procptr, flags, pages, "%s", procname);
  470                 if (error)
  471                         return (error);
  472                 td = FIRST_THREAD_IN_PROC(*procptr);
  473                 if (tdptr)
  474                         *tdptr = td;
  475                 va_start(ap, fmt);
  476                 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
  477                 va_end(ap);
  478 #ifdef KTR
  479                 sched_clear_tdname(td);
  480 #endif
  481                 return (0); 
  482         }
  483         va_start(ap, fmt);
  484         vsnprintf(buf, sizeof(buf), fmt, ap);
  485         va_end(ap);
  486         error = kthread_add(func, arg, *procptr,
  487                     tdptr, flags, pages, "%s", buf);
  488         return (error);
  489 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_kthread.c

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