kern_kthread.c

Version: - FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10

    1 /*      $NetBSD: kern_kthread.c,v 1.47 2022/09/13 09:37:49 riastradh Exp $      */
    2 
    3 /*-
    4  * Copyright (c) 1998, 1999, 2007, 2009, 2019 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
    9  * NASA Ames Research Center, and by Andrew Doran.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   30  * POSSIBILITY OF SUCH DAMAGE.
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __KERNEL_RCSID(0, "$NetBSD: kern_kthread.c,v 1.47 2022/09/13 09:37:49 riastradh Exp $");
   35 
   36 #include <sys/param.h>
   37 #include <sys/cpu.h>
   38 #include <sys/systm.h>
   39 #include <sys/kernel.h>
   40 #include <sys/kthread.h>
   41 #include <sys/mutex.h>
   42 #include <sys/sched.h>
   43 #include <sys/kmem.h>
   44 #include <sys/msan.h>
   45 
   46 #include <uvm/uvm_extern.h>
   47 
   48 static lwp_t *          kthread_jtarget;
   49 static kmutex_t         kthread_lock;
   50 static kcondvar_t       kthread_cv;
   51 
   52 void
   53 kthread_sysinit(void)
   54 {
   55 
   56         mutex_init(&kthread_lock, MUTEX_DEFAULT, IPL_NONE);
   57         cv_init(&kthread_cv, "kthrwait");
   58         kthread_jtarget = NULL;
   59 }
   60 
   61 /*
   62  * kthread_create: create a kernel thread, that is, system-only LWP.
   63  */
   64 int
   65 kthread_create(pri_t pri, int flag, struct cpu_info *ci,
   66     void (*func)(void *), void *arg, lwp_t **lp, const char *fmt, ...)
   67 {
   68         lwp_t *l;
   69         vaddr_t uaddr;
   70         int error, lc;
   71         va_list ap;
   72 
   73         KASSERT((flag & KTHREAD_INTR) == 0 || (flag & KTHREAD_MPSAFE) != 0);
   74 
   75         uaddr = uvm_uarea_system_alloc(
   76            (flag & (KTHREAD_INTR|KTHREAD_IDLE)) == KTHREAD_IDLE ? ci : NULL);
   77         if (uaddr == 0) {
   78                 return ENOMEM;
   79         }
   80         kmsan_orig((void *)uaddr, USPACE, KMSAN_TYPE_POOL, __RET_ADDR);
   81         if ((flag & KTHREAD_TS) != 0) {
   82                 lc = SCHED_OTHER;
   83         } else {
   84                 lc = SCHED_RR;
   85         }
   86 
   87         error = lwp_create(&lwp0, &proc0, uaddr, LWP_DETACHED, NULL,
   88             0, func, arg, &l, lc, &lwp0.l_sigmask, &lwp0.l_sigstk);
   89         if (error) {
   90                 uvm_uarea_system_free(uaddr);
   91                 return error;
   92         }
   93         if (fmt != NULL) {
   94                 l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP);
   95                 va_start(ap, fmt);
   96                 vsnprintf(l->l_name, MAXCOMLEN, fmt, ap);
   97                 va_end(ap);
   98         }
   99 
  100         /*
  101          * Set parameters.
  102          */
  103         if (pri == PRI_NONE) {
  104                 if ((flag & KTHREAD_TS) != 0) {
  105                         /* Maximum user priority level. */
  106                         pri = MAXPRI_USER;
  107                 } else {
  108                         /* Minimum kernel priority level. */
  109                         pri = PRI_KTHREAD;
  110                 }
  111         }
  112         mutex_enter(proc0.p_lock);
  113         lwp_lock(l);
  114         lwp_changepri(l, pri);
  115         if (ci != NULL) {
  116                 if (ci != l->l_cpu) {
  117                         lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock);
  118                         lwp_lock(l);
  119                 }
  120                 l->l_pflag |= LP_BOUND;
  121                 l->l_cpu = ci;
  122         }
  123 
  124         if ((flag & KTHREAD_MUSTJOIN) != 0) {
  125                 KASSERT(lp != NULL);
  126                 l->l_pflag |= LP_MUSTJOIN;
  127         }
  128         if ((flag & KTHREAD_INTR) != 0) {
  129                 l->l_pflag |= LP_INTR;
  130         }
  131         if ((flag & KTHREAD_MPSAFE) == 0) {
  132                 l->l_pflag &= ~LP_MPSAFE;
  133         }
  134 
  135         /*
  136          * Set the new LWP running, unless the caller has requested
  137          * otherwise.
  138          */
  139         KASSERT(l->l_stat == LSIDL);
  140         if ((flag & KTHREAD_IDLE) == 0) {
  141                 setrunnable(l);
  142                 /* LWP now unlocked */
  143         } else {
  144                 lwp_unlock(l);
  145         }
  146         mutex_exit(proc0.p_lock);
  147 
  148         /* All done! */
  149         if (lp != NULL) {
  150                 *lp = l;
  151         }
  152         return 0;
  153 }
  154 
  155 /*
  156  * Cause a kernel thread to exit.  Assumes the exiting thread is the
  157  * current context.
  158  */
  159 void
  160 kthread_exit(int ecode)
  161 {
  162         const char *name;
  163         lwp_t *l = curlwp;
  164 
  165         /* We can't do much with the exit code, so just report it. */
  166         if (ecode != 0) {
  167                 if ((name = l->l_name) == NULL)
  168                         name = "unnamed";
  169                 printf("WARNING: kthread `%s' (%d) exits with status %d\n",
  170                     name, l->l_lid, ecode);
  171         }
  172 
  173         /* Barrier for joining. */
  174         if (l->l_pflag & LP_MUSTJOIN) {
  175                 mutex_enter(&kthread_lock);
  176                 while (kthread_jtarget != l) {
  177                         cv_wait(&kthread_cv, &kthread_lock);
  178                 }
  179                 kthread_jtarget = NULL;
  180                 cv_broadcast(&kthread_cv);
  181                 mutex_exit(&kthread_lock);
  182         }
  183 
  184         /* If the kernel lock is held, we need to drop it now. */
  185         if ((l->l_pflag & LP_MPSAFE) == 0) {
  186                 KERNEL_UNLOCK_LAST(l);
  187         }
  188 
  189         /* And exit.. */
  190         lwp_exit(l);
  191         panic("kthread_exit");
  192 }
  193 
  194 /*
  195  * Wait for a kthread to exit, as pthread_join().
  196  */
  197 int
  198 kthread_join(lwp_t *l)
  199 {
  200 
  201         KASSERT((l->l_flag & LW_SYSTEM) != 0);
  202         KASSERT((l->l_pflag & LP_MUSTJOIN) != 0);
  203 
  204         /*
  205          * - Wait if some other thread has occupied the target.
  206          * - Specify our kthread as a target and notify it.
  207          * - Wait for the target kthread to notify us.
  208          */
  209         mutex_enter(&kthread_lock);
  210         while (kthread_jtarget) {
  211                 cv_wait(&kthread_cv, &kthread_lock);
  212         }
  213         kthread_jtarget = l;
  214         cv_broadcast(&kthread_cv);
  215         while (kthread_jtarget == l) {
  216                 cv_wait(&kthread_cv, &kthread_lock);
  217         }
  218         mutex_exit(&kthread_lock);
  219 
  220         return 0;
  221 }
  222 
  223 /*
  224  * kthread_fpu_enter()
  225  *
  226  *      Allow the current lwp, which must be a kthread, to use the FPU.
  227  *      Return a cookie that must be passed to kthread_fpu_exit when
  228  *      done.  Must be used only in thread context.  Recursive -- you
  229  *      can call kthread_fpu_enter several times in a row as long as
  230  *      you pass the cookies in reverse order to kthread_fpu_exit.
  231  */
  232 int
  233 kthread_fpu_enter(void)
  234 {
  235         struct lwp *l = curlwp;
  236         int s;
  237 
  238         KASSERTMSG(!cpu_intr_p(),
  239             "%s is not allowed in interrupt context", __func__);
  240         KASSERTMSG(!cpu_softintr_p(),
  241             "%s is not allowed in interrupt context", __func__);
  242 
  243         /*
  244          * Remember whether this thread already had FPU access, and
  245          * mark this thread as having FPU access.
  246          */
  247         lwp_lock(l);
  248         KASSERTMSG(l->l_flag & LW_SYSTEM,
  249             "%s is allowed only in kthreads", __func__);
  250         s = l->l_flag & LW_SYSTEM_FPU;
  251         l->l_flag |= LW_SYSTEM_FPU;
  252         lwp_unlock(l);
  253 
  254         /* Take MD steps to enable the FPU if necessary.  */
  255         if (s == 0)
  256                 kthread_fpu_enter_md();
  257 
  258         return s;
  259 }
  260 
  261 /*
  262  * kthread_fpu_exit(s)
  263  *
  264  *      Restore the current lwp's FPU access to what it was before the
  265  *      matching call to kthread_fpu_enter() that returned s.  Must be
  266  *      used only in thread context.
  267  */
  268 void
  269 kthread_fpu_exit(int s)
  270 {
  271         struct lwp *l = curlwp;
  272 
  273         KASSERT(s == (s & LW_SYSTEM_FPU));
  274         KASSERTMSG(!cpu_intr_p(),
  275             "%s is not allowed in interrupt context", __func__);
  276         KASSERTMSG(!cpu_softintr_p(),
  277             "%s is not allowed in interrupt context", __func__);
  278 
  279         lwp_lock(l);
  280         KASSERTMSG(l->l_flag & LW_SYSTEM,
  281             "%s is allowed only in kthreads", __func__);
  282         KASSERT(l->l_flag & LW_SYSTEM_FPU);
  283         l->l_flag ^= s ^ LW_SYSTEM_FPU;
  284         lwp_unlock(l);
  285 
  286         /* Take MD steps to zero and disable the FPU if necessary.  */
  287         if (s == 0)
  288                 kthread_fpu_exit_md();
  289 }

Cache object: a5d9c7d889ff6cae694f4687cf4ac8e4

[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.

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

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