sys/kern/kern_kthread.c

   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("$FreeBSD$");
  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/signalvar.h>
  38 #include <sys/sx.h>
  39 #include <sys/unistd.h>
  40 #include <sys/wait.h>
  41 #include <sys/sched.h>
  42 #include <vm/vm.h>
  43 #include <vm/vm_extern.h>
  44
  45 #include <machine/stdarg.h>
  46
  47 /*
  48  * Start a kernel process.  This is called after a fork() call in
  49  * mi_startup() in the file kern/init_main.c.
  50  *
  51  * This function is used to start "internal" daemons and intended
  52  * to be called from SYSINIT().
  53  */
  54 void
  55 kproc_start(udata)
  56         const void *udata;
  57 {
  58         const struct kproc_desc *kp = udata;
  59         int error;
  60
  61         error = kproc_create((void (*)(void *))kp->func, NULL,
  62                     kp->global_procpp, 0, 0, "%s", kp->arg0);
  63         if (error)
  64                 panic("kproc_start: %s: error %d", kp->arg0, error);
  65 }
  66
  67 /*
  68  * Create a kernel process/thread/whatever.  It shares its address space
  69  * with proc0 - ie: kernel only.
  70  *
  71  * func is the function to start.
  72  * arg is the parameter to pass to function on first startup.
  73  * newpp is the return value pointing to the thread's struct proc.
  74  * flags are flags to fork1 (in unistd.h)
  75  * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
  76  */
  77 int
  78 kproc_create(void (*func)(void *), void *arg,
  79     struct proc **newpp, int flags, int pages, const char *fmt, ...)
  80 {
  81         int error;
  82         va_list ap;
  83         struct thread *td;
  84         struct proc *p2;
  85
  86         if (!proc0.p_stats)
  87                 panic("kproc_create called too soon");
  88
  89         error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags,
  90             pages, &p2);
  91         if (error)
  92                 return error;
  93
  94         /* save a global descriptor, if desired */
  95         if (newpp != NULL)
  96                 *newpp = p2;
  97
  98         /* this is a non-swapped system process */
  99         PROC_LOCK(p2);
 100         td = FIRST_THREAD_IN_PROC(p2);
 101         p2->p_flag |= P_SYSTEM | P_KTHREAD;
 102         td->td_pflags |= TDP_KTHREAD;
 103         mtx_lock(&p2->p_sigacts->ps_mtx);
 104         p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
 105         mtx_unlock(&p2->p_sigacts->ps_mtx);
 106         PROC_UNLOCK(p2);
 107
 108         /* set up arg0 for 'ps', et al */
 109         va_start(ap, fmt);
 110         vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
 111         va_end(ap);
 112         /* set up arg0 for 'ps', et al */
 113         va_start(ap, fmt);
 114         vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
 115         va_end(ap);
 116
 117         /* call the processes' main()... */
 118         cpu_set_fork_handler(td, func, arg);
 119         TD_SET_CAN_RUN(td);
 120
 121         /* Delay putting it on the run queue until now. */
 122         if (!(flags & RFSTOPPED)) {
 123                 thread_lock(td);
 124                 sched_add(td, SRQ_BORING);
 125                 thread_unlock(td);
 126         }
 127
 128         return 0;
 129 }
 130
 131 void
 132 kproc_exit(int ecode)
 133 {
 134         struct thread *td;
 135         struct proc *p;
 136
 137         td = curthread;
 138         p = td->td_proc;
 139
 140         /*
 141          * Reparent curthread from proc0 to init so that the zombie
 142          * is harvested.
 143          */
 144         sx_xlock(&proctree_lock);
 145         PROC_LOCK(p);
 146         proc_reparent(p, initproc);
 147         PROC_UNLOCK(p);
 148         sx_xunlock(&proctree_lock);
 149
 150         /*
 151          * Wakeup anyone waiting for us to exit.
 152          */
 153         wakeup(p);
 154
 155         /* Buh-bye! */
 156         exit1(td, W_EXITCODE(ecode, 0));
 157 }
 158
 159 /*
 160  * Advise a kernel process to suspend (or resume) in its main loop.
 161  * Participation is voluntary.
 162  */
 163 int
 164 kproc_suspend(struct proc *p, int timo)
 165 {
 166         /*
 167          * Make sure this is indeed a system process and we can safely
 168          * use the p_siglist field.
 169          */
 170         PROC_LOCK(p);
 171         if ((p->p_flag & P_KTHREAD) == 0) {
 172                 PROC_UNLOCK(p);
 173                 return (EINVAL);
 174         }
 175         SIGADDSET(p->p_siglist, SIGSTOP);
 176         wakeup(p);
 177         return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo);
 178 }
 179
 180 int
 181 kproc_resume(struct proc *p)
 182 {
 183         /*
 184          * Make sure this is indeed a system process and we can safely
 185          * use the p_siglist field.
 186          */
 187         PROC_LOCK(p);
 188         if ((p->p_flag & P_KTHREAD) == 0) {
 189                 PROC_UNLOCK(p);
 190                 return (EINVAL);
 191         }
 192         SIGDELSET(p->p_siglist, SIGSTOP);
 193         PROC_UNLOCK(p);
 194         wakeup(&p->p_siglist);
 195         return (0);
 196 }
 197
 198 void
 199 kproc_suspend_check(struct proc *p)
 200 {
 201         PROC_LOCK(p);
 202         while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
 203                 wakeup(&p->p_siglist);
 204                 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0);
 205         }
 206         PROC_UNLOCK(p);
 207 }
 208
 209
 210 /*
 211  * Start a kernel thread.
 212  *
 213  * This function is used to start "internal" daemons and intended
 214  * to be called from SYSINIT().
 215  */
 216
 217 void
 218 kthread_start(udata)
 219         const void *udata;
 220 {
 221         const struct kthread_desc       *kp = udata;
 222         int error;
 223
 224         error = kthread_add((void (*)(void *))kp->func, NULL,
 225                     NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
 226         if (error)
 227                 panic("kthread_start: %s: error %d", kp->arg0, error);
 228 }
 229
 230 /*
 231  * Create a kernel thread.  It shares its address space
 232  * with proc0 - ie: kernel only.
 233  *
 234  * func is the function to start.
 235  * arg is the parameter to pass to function on first startup.
 236  * newtdp is the return value pointing to the thread's struct thread.
 237  *  ** XXX fix this --> flags are flags to fork1 (in unistd.h)
 238  * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
 239  */
 240 int
 241 kthread_add(void (*func)(void *), void *arg, struct proc *p,
 242     struct thread **newtdp, int flags, int pages, const char *fmt, ...)
 243 {
 244         va_list ap;
 245         struct thread *newtd, *oldtd;
 246
 247         if (!proc0.p_stats)
 248                 panic("kthread_add called too soon");
 249
 250         /* If no process supplied, put it on proc0 */
 251         if (p == NULL) {
 252                 p = &proc0;
 253                 oldtd = &thread0;
 254         } else {
 255                 oldtd = FIRST_THREAD_IN_PROC(p);
 256         }
 257
 258         /* Initialize our new td  */
 259         newtd = thread_alloc();
 260         if (newtd == NULL)
 261                 return (ENOMEM);
 262
 263         bzero(&newtd->td_startzero,
 264             __rangeof(struct thread, td_startzero, td_endzero));
 265 /* XXX check if we should zero. */
 266         bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
 267             __rangeof(struct thread, td_startcopy, td_endcopy));
 268
 269         /* set up arg0 for 'ps', et al */
 270         va_start(ap, fmt);
 271         vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
 272         va_end(ap);
 273
 274         newtd->td_proc = p;  /* needed for cpu_set_upcall */
 275
 276         /* XXX optimise this probably? */
 277         /* On x86 (and probably the others too) it is way too full of junk */
 278         /* Needs a better name */
 279         cpu_set_upcall(newtd, oldtd);
 280         /* put the designated function(arg) as the resume context */
 281         cpu_set_fork_handler(newtd, func, arg);
 282
 283         newtd->td_pflags |= TDP_KTHREAD;
 284         newtd->td_ucred = crhold(p->p_ucred);
 285         /* Allocate and switch to an alternate kstack if specified. */
 286         if (pages != 0)
 287                 vm_thread_new_altkstack(newtd, pages);
 288
 289         /* this code almost the same as create_thread() in kern_thr.c */
 290         PROC_LOCK(p);
 291         p->p_flag |= P_HADTHREADS;
 292         newtd->td_sigmask = oldtd->td_sigmask; /* XXX dubious */
 293         thread_link(newtd, p);
 294         thread_lock(oldtd);
 295         /* let the scheduler know about these things. */
 296         sched_fork_thread(oldtd, newtd);
 297         TD_SET_CAN_RUN(newtd);
 298         thread_unlock(oldtd);
 299         PROC_UNLOCK(p);
 300
 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         /* A module may be waiting for us to exit. */
 319         wakeup(curthread);
 320
 321         /*
 322          * We could rely on thread_exit to call exit1() but
 323          * there is extra work that needs to be done
 324          */
 325         if (curthread->td_proc->p_numthreads == 1)
 326                 kproc_exit(0);  /* never returns */
 327
 328         p = curthread->td_proc;
 329         PROC_LOCK(p);
 330         PROC_SLOCK(p);
 331         thread_exit();
 332 }
 333
 334 /*
 335  * Advise a kernel process to suspend (or resume) in its main loop.
 336  * Participation is voluntary.
 337  */
 338 int
 339 kthread_suspend(struct thread *td, int timo)
 340 {
 341         if ((td->td_pflags & TDP_KTHREAD) == 0) {
 342                 return (EINVAL);
 343         }
 344         thread_lock(td);
 345         td->td_flags |= TDF_KTH_SUSP;
 346         thread_unlock(td);
 347         /*
 348          * If it's stopped for some other reason,
 349          * kick it to notice our request
 350          * or we'll end up timing out
 351          */
 352         wakeup(td); /* traditional  place for kernel threads to sleep on */ /* XXX ?? */
 353         return (tsleep(&td->td_flags, PPAUSE | PDROP, "suspkt", timo));
 354 }
 355
 356 /*
 357  * let the kthread it can keep going again.
 358  */
 359 int
 360 kthread_resume(struct thread *td)
 361 {
 362         if ((td->td_pflags & TDP_KTHREAD) == 0) {
 363                 return (EINVAL);
 364         }
 365         thread_lock(td);
 366         td->td_flags &= ~TDF_KTH_SUSP;
 367         thread_unlock(td);
 368         wakeup(&td->td_name);
 369         return (0);
 370 }
 371
 372 /*
 373  * Used by the thread to poll as to whether it should yield/sleep
 374  * and notify the caller that is has happened.
 375  */
 376 void
 377 kthread_suspend_check(struct thread *td)
 378 {
 379         while (td->td_flags & TDF_KTH_SUSP) {
 380                 /*
 381                  * let the caller know we got the message then sleep
 382                  */
 383                 wakeup(&td->td_flags);
 384                 tsleep(&td->td_name, PPAUSE, "ktsusp", 0);
 385         }
 386 }
 387
 388 int
 389 kproc_kthread_add(void (*func)(void *), void *arg,
 390             struct proc **procptr, struct thread **tdptr,
 391             int flags, int pages, char * procname, const char *fmt, ...)
 392 {
 393         int error;
 394         va_list ap;
 395         char buf[100];
 396         struct thread *td;
 397
 398         if (*procptr == 0) {
 399                 error = kproc_create(func, arg,
 400                         procptr, flags, pages, "%s", procname);
 401                 if (error)
 402                         return (error);
 403                 td = FIRST_THREAD_IN_PROC(*procptr);
 404                 if (tdptr)
 405                         *tdptr = td;
 406                 va_start(ap, fmt);
 407                 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
 408                 va_end(ap);
 409                 return (0);
 410         }
 411         va_start(ap, fmt);
 412         vsnprintf(buf, sizeof(buf), fmt, ap);
 413         va_end(ap);
 414         error = kthread_add(func, arg, *procptr,
 415                     tdptr, flags, pages, "%s", buf);
 416         return (error);
 417 }