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/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); 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 } 458