kern_kthread.c revision 304905
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: stable/10/sys/kern/kern_kthread.c 304905 2016-08-27 11:45:05Z kib $"); 29 30#include <sys/param.h> 31#include <sys/systm.h> 32#include <sys/cpuset.h> 33#include <sys/kthread.h> 34#include <sys/lock.h> 35#include <sys/mutex.h> 36#include <sys/proc.h> 37#include <sys/resourcevar.h> 38#include <sys/rwlock.h> 39#include <sys/signalvar.h> 40#include <sys/sx.h> 41#include <sys/umtx.h> 42#include <sys/unistd.h> 43#include <sys/wait.h> 44#include <sys/sched.h> 45#include <vm/vm.h> 46#include <vm/vm_extern.h> 47 48#include <machine/stdarg.h> 49 50/* 51 * Start a kernel process. This is called after a fork() call in 52 * mi_startup() in the file kern/init_main.c. 53 * 54 * This function is used to start "internal" daemons and intended 55 * to be called from SYSINIT(). 56 */ 57void 58kproc_start(udata) 59 const void *udata; 60{ 61 const struct kproc_desc *kp = udata; 62 int error; 63 64 error = kproc_create((void (*)(void *))kp->func, NULL, 65 kp->global_procpp, 0, 0, "%s", kp->arg0); 66 if (error) 67 panic("kproc_start: %s: error %d", kp->arg0, error); 68} 69 70/* 71 * Create a kernel process/thread/whatever. It shares its address space 72 * with proc0 - ie: kernel only. 73 * 74 * func is the function to start. 75 * arg is the parameter to pass to function on first startup. 76 * newpp is the return value pointing to the thread's struct proc. 77 * flags are flags to fork1 (in unistd.h) 78 * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.). 79 */ 80int 81kproc_create(void (*func)(void *), void *arg, 82 struct proc **newpp, int flags, int pages, const char *fmt, ...) 83{ 84 int error; 85 va_list ap; 86 struct thread *td; 87 struct proc *p2; 88 89 if (!proc0.p_stats) 90 panic("kproc_create called too soon"); 91 92 error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags, 93 pages, &p2, NULL, 0); 94 if (error) 95 return error; 96 97 /* save a global descriptor, if desired */ 98 if (newpp != NULL) 99 *newpp = p2; 100 101 /* this is a non-swapped system process */ 102 PROC_LOCK(p2); 103 td = FIRST_THREAD_IN_PROC(p2); 104 p2->p_flag |= P_SYSTEM | P_KTHREAD; 105 td->td_pflags |= TDP_KTHREAD; 106 mtx_lock(&p2->p_sigacts->ps_mtx); 107 p2->p_sigacts->ps_flag |= PS_NOCLDWAIT; 108 mtx_unlock(&p2->p_sigacts->ps_mtx); 109 PROC_UNLOCK(p2); 110 111 /* set up arg0 for 'ps', et al */ 112 va_start(ap, fmt); 113 vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap); 114 va_end(ap); 115 /* set up arg0 for 'ps', et al */ 116 va_start(ap, fmt); 117 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap); 118 va_end(ap); 119#ifdef KTR 120 sched_clear_tdname(td); 121#endif 122 123 /* call the processes' main()... */ 124 cpu_set_fork_handler(td, func, arg); 125 126 /* Avoid inheriting affinity from a random parent. */ 127 cpuset_setthread(td->td_tid, cpuset_root); 128 thread_lock(td); 129 TD_SET_CAN_RUN(td); 130 sched_prio(td, PVM); 131 sched_user_prio(td, PUSER); 132 133 /* Delay putting it on the run queue until now. */ 134 if (!(flags & RFSTOPPED)) 135 sched_add(td, SRQ_BORING); 136 thread_unlock(td); 137 138 return 0; 139} 140 141void 142kproc_exit(int ecode) 143{ 144 struct thread *td; 145 struct proc *p; 146 147 td = curthread; 148 p = td->td_proc; 149 150 /* 151 * Reparent curthread from proc0 to init so that the zombie 152 * is harvested. 153 */ 154 sx_xlock(&proctree_lock); 155 PROC_LOCK(p); 156 proc_reparent(p, initproc); 157 PROC_UNLOCK(p); 158 sx_xunlock(&proctree_lock); 159 160 /* 161 * Wakeup anyone waiting for us to exit. 162 */ 163 wakeup(p); 164 165 /* Buh-bye! */ 166 exit1(td, W_EXITCODE(ecode, 0)); 167} 168 169/* 170 * Advise a kernel process to suspend (or resume) in its main loop. 171 * Participation is voluntary. 172 */ 173int 174kproc_suspend(struct proc *p, int timo) 175{ 176 /* 177 * Make sure this is indeed a system process and we can safely 178 * use the p_siglist field. 179 */ 180 PROC_LOCK(p); 181 if ((p->p_flag & P_KTHREAD) == 0) { 182 PROC_UNLOCK(p); 183 return (EINVAL); 184 } 185 SIGADDSET(p->p_siglist, SIGSTOP); 186 wakeup(p); 187 return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkp", timo); 188} 189 190int 191kproc_resume(struct proc *p) 192{ 193 /* 194 * Make sure this is indeed a system process and we can safely 195 * use the p_siglist field. 196 */ 197 PROC_LOCK(p); 198 if ((p->p_flag & P_KTHREAD) == 0) { 199 PROC_UNLOCK(p); 200 return (EINVAL); 201 } 202 SIGDELSET(p->p_siglist, SIGSTOP); 203 PROC_UNLOCK(p); 204 wakeup(&p->p_siglist); 205 return (0); 206} 207 208void 209kproc_suspend_check(struct proc *p) 210{ 211 PROC_LOCK(p); 212 while (SIGISMEMBER(p->p_siglist, SIGSTOP)) { 213 wakeup(&p->p_siglist); 214 msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "kpsusp", 0); 215 } 216 PROC_UNLOCK(p); 217} 218 219 220/* 221 * Start a kernel thread. 222 * 223 * This function is used to start "internal" daemons and intended 224 * to be called from SYSINIT(). 225 */ 226 227void 228kthread_start(udata) 229 const void *udata; 230{ 231 const struct kthread_desc *kp = udata; 232 int error; 233 234 error = kthread_add((void (*)(void *))kp->func, NULL, 235 NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0); 236 if (error) 237 panic("kthread_start: %s: error %d", kp->arg0, error); 238} 239 240/* 241 * Create a kernel thread. It shares its address space 242 * with proc0 - ie: kernel only. 243 * 244 * func is the function to start. 245 * arg is the parameter to pass to function on first startup. 246 * newtdp is the return value pointing to the thread's struct thread. 247 * ** XXX fix this --> flags are flags to fork1 (in unistd.h) 248 * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.). 249 */ 250int 251kthread_add(void (*func)(void *), void *arg, struct proc *p, 252 struct thread **newtdp, int flags, int pages, const char *fmt, ...) 253{ 254 va_list ap; 255 struct thread *newtd, *oldtd; 256 257 if (!proc0.p_stats) 258 panic("kthread_add called too soon"); 259 260 /* If no process supplied, put it on proc0 */ 261 if (p == NULL) 262 p = &proc0; 263 264 /* Initialize our new td */ 265 newtd = thread_alloc(pages); 266 if (newtd == NULL) 267 return (ENOMEM); 268 269 PROC_LOCK(p); 270 oldtd = FIRST_THREAD_IN_PROC(p); 271 272 bzero(&newtd->td_startzero, 273 __rangeof(struct thread, td_startzero, td_endzero)); 274 newtd->td_su = NULL; 275 newtd->td_sleeptimo = 0; 276 bcopy(&oldtd->td_startcopy, &newtd->td_startcopy, 277 __rangeof(struct thread, td_startcopy, td_endcopy)); 278 279 /* set up arg0 for 'ps', et al */ 280 va_start(ap, fmt); 281 vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap); 282 va_end(ap); 283 284 newtd->td_proc = p; /* needed for cpu_set_upcall */ 285 286 /* XXX optimise this probably? */ 287 /* On x86 (and probably the others too) it is way too full of junk */ 288 /* Needs a better name */ 289 cpu_set_upcall(newtd, oldtd); 290 /* put the designated function(arg) as the resume context */ 291 cpu_set_fork_handler(newtd, func, arg); 292 293 newtd->td_pflags |= TDP_KTHREAD; 294 newtd->td_ucred = crhold(p->p_ucred); 295 296 /* this code almost the same as create_thread() in kern_thr.c */ 297 p->p_flag |= P_HADTHREADS; 298 thread_link(newtd, p); 299 thread_lock(oldtd); 300 /* let the scheduler know about these things. */ 301 sched_fork_thread(oldtd, newtd); 302 TD_SET_CAN_RUN(newtd); 303 thread_unlock(oldtd); 304 PROC_UNLOCK(p); 305 306 tidhash_add(newtd); 307 308 /* Avoid inheriting affinity from a random parent. */ 309 cpuset_setthread(newtd->td_tid, cpuset_root); 310 311 /* Delay putting it on the run queue until now. */ 312 if (!(flags & RFSTOPPED)) { 313 thread_lock(newtd); 314 sched_add(newtd, SRQ_BORING); 315 thread_unlock(newtd); 316 } 317 if (newtdp) 318 *newtdp = newtd; 319 return 0; 320} 321 322void 323kthread_exit(void) 324{ 325 struct proc *p; 326 struct thread *td; 327 328 td = curthread; 329 p = td->td_proc; 330 331 /* A module may be waiting for us to exit. */ 332 wakeup(td); 333 334 /* 335 * The last exiting thread in a kernel process must tear down 336 * the whole process. 337 */ 338 rw_wlock(&tidhash_lock); 339 PROC_LOCK(p); 340 if (p->p_numthreads == 1) { 341 PROC_UNLOCK(p); 342 rw_wunlock(&tidhash_lock); 343 kproc_exit(0); 344 } 345 LIST_REMOVE(td, td_hash); 346 rw_wunlock(&tidhash_lock); 347 umtx_thread_exit(td); 348 tdsigcleanup(td); 349 PROC_SLOCK(p); 350 thread_exit(); 351} 352 353/* 354 * Advise a kernel process to suspend (or resume) in its main loop. 355 * Participation is voluntary. 356 */ 357int 358kthread_suspend(struct thread *td, int timo) 359{ 360 struct proc *p; 361 362 p = td->td_proc; 363 364 /* 365 * td_pflags should not be read by any thread other than 366 * curthread, but as long as this flag is invariant during the 367 * thread's lifetime, it is OK to check its state. 368 */ 369 if ((td->td_pflags & TDP_KTHREAD) == 0) 370 return (EINVAL); 371 372 /* 373 * The caller of the primitive should have already checked that the 374 * thread is up and running, thus not being blocked by other 375 * conditions. 376 */ 377 PROC_LOCK(p); 378 thread_lock(td); 379 td->td_flags |= TDF_KTH_SUSP; 380 thread_unlock(td); 381 return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt", 382 timo)); 383} 384 385/* 386 * Resume a thread previously put asleep with kthread_suspend(). 387 */ 388int 389kthread_resume(struct thread *td) 390{ 391 struct proc *p; 392 393 p = td->td_proc; 394 395 /* 396 * td_pflags should not be read by any thread other than 397 * curthread, but as long as this flag is invariant during the 398 * thread's lifetime, it is OK to check its state. 399 */ 400 if ((td->td_pflags & TDP_KTHREAD) == 0) 401 return (EINVAL); 402 403 PROC_LOCK(p); 404 thread_lock(td); 405 td->td_flags &= ~TDF_KTH_SUSP; 406 thread_unlock(td); 407 wakeup(&td->td_flags); 408 PROC_UNLOCK(p); 409 return (0); 410} 411 412/* 413 * Used by the thread to poll as to whether it should yield/sleep 414 * and notify the caller that is has happened. 415 */ 416void 417kthread_suspend_check() 418{ 419 struct proc *p; 420 struct thread *td; 421 422 td = curthread; 423 p = td->td_proc; 424 425 if ((td->td_pflags & TDP_KTHREAD) == 0) 426 panic("%s: curthread is not a valid kthread", __func__); 427 428 /* 429 * As long as the double-lock protection is used when accessing the 430 * TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex 431 * is fine. 432 */ 433 PROC_LOCK(p); 434 while (td->td_flags & TDF_KTH_SUSP) { 435 wakeup(&td->td_flags); 436 msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0); 437 } 438 PROC_UNLOCK(p); 439} 440 441int 442kproc_kthread_add(void (*func)(void *), void *arg, 443 struct proc **procptr, struct thread **tdptr, 444 int flags, int pages, const char *procname, const char *fmt, ...) 445{ 446 int error; 447 va_list ap; 448 char buf[100]; 449 struct thread *td; 450 451 if (*procptr == 0) { 452 error = kproc_create(func, arg, 453 procptr, flags, pages, "%s", procname); 454 if (error) 455 return (error); 456 td = FIRST_THREAD_IN_PROC(*procptr); 457 if (tdptr) 458 *tdptr = td; 459 va_start(ap, fmt); 460 vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap); 461 va_end(ap); 462#ifdef KTR 463 sched_clear_tdname(td); 464#endif 465 return (0); 466 } 467 va_start(ap, fmt); 468 vsnprintf(buf, sizeof(buf), fmt, ap); 469 va_end(ap); 470 error = kthread_add(func, arg, *procptr, 471 tdptr, flags, pages, "%s", buf); 472 return (error); 473} 474