| 1 | /* $NetBSD: kern_lwp.c,v 1.185 2016/07/03 14:24:58 christos Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2001, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Nathan J. Williams, and Andrew Doran. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * |
| 19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 29 | * POSSIBILITY OF SUCH DAMAGE. |
| 30 | */ |
| 31 | |
| 32 | /* |
| 33 | * Overview |
| 34 | * |
| 35 | * Lightweight processes (LWPs) are the basic unit or thread of |
| 36 | * execution within the kernel. The core state of an LWP is described |
| 37 | * by "struct lwp", also known as lwp_t. |
| 38 | * |
| 39 | * Each LWP is contained within a process (described by "struct proc"), |
| 40 | * Every process contains at least one LWP, but may contain more. The |
| 41 | * process describes attributes shared among all of its LWPs such as a |
| 42 | * private address space, global execution state (stopped, active, |
| 43 | * zombie, ...), signal disposition and so on. On a multiprocessor |
| 44 | * machine, multiple LWPs be executing concurrently in the kernel. |
| 45 | * |
| 46 | * Execution states |
| 47 | * |
| 48 | * At any given time, an LWP has overall state that is described by |
| 49 | * lwp::l_stat. The states are broken into two sets below. The first |
| 50 | * set is guaranteed to represent the absolute, current state of the |
| 51 | * LWP: |
| 52 | * |
| 53 | * LSONPROC |
| 54 | * |
| 55 | * On processor: the LWP is executing on a CPU, either in the |
| 56 | * kernel or in user space. |
| 57 | * |
| 58 | * LSRUN |
| 59 | * |
| 60 | * Runnable: the LWP is parked on a run queue, and may soon be |
| 61 | * chosen to run by an idle processor, or by a processor that |
| 62 | * has been asked to preempt a currently runnning but lower |
| 63 | * priority LWP. |
| 64 | * |
| 65 | * LSIDL |
| 66 | * |
| 67 | * Idle: the LWP has been created but has not yet executed, |
| 68 | * or it has ceased executing a unit of work and is waiting |
| 69 | * to be started again. |
| 70 | * |
| 71 | * LSSUSPENDED: |
| 72 | * |
| 73 | * Suspended: the LWP has had its execution suspended by |
| 74 | * another LWP in the same process using the _lwp_suspend() |
| 75 | * system call. User-level LWPs also enter the suspended |
| 76 | * state when the system is shutting down. |
| 77 | * |
| 78 | * The second set represent a "statement of intent" on behalf of the |
| 79 | * LWP. The LWP may in fact be executing on a processor, may be |
| 80 | * sleeping or idle. It is expected to take the necessary action to |
| 81 | * stop executing or become "running" again within a short timeframe. |
| 82 | * The LP_RUNNING flag in lwp::l_pflag indicates that an LWP is running. |
| 83 | * Importantly, it indicates that its state is tied to a CPU. |
| 84 | * |
| 85 | * LSZOMB: |
| 86 | * |
| 87 | * Dead or dying: the LWP has released most of its resources |
| 88 | * and is about to switch away into oblivion, or has already |
| 89 | * switched away. When it switches away, its few remaining |
| 90 | * resources can be collected. |
| 91 | * |
| 92 | * LSSLEEP: |
| 93 | * |
| 94 | * Sleeping: the LWP has entered itself onto a sleep queue, and |
| 95 | * has switched away or will switch away shortly to allow other |
| 96 | * LWPs to run on the CPU. |
| 97 | * |
| 98 | * LSSTOP: |
| 99 | * |
| 100 | * Stopped: the LWP has been stopped as a result of a job |
| 101 | * control signal, or as a result of the ptrace() interface. |
| 102 | * |
| 103 | * Stopped LWPs may run briefly within the kernel to handle |
| 104 | * signals that they receive, but will not return to user space |
| 105 | * until their process' state is changed away from stopped. |
| 106 | * |
| 107 | * Single LWPs within a process can not be set stopped |
| 108 | * selectively: all actions that can stop or continue LWPs |
| 109 | * occur at the process level. |
| 110 | * |
| 111 | * State transitions |
| 112 | * |
| 113 | * Note that the LSSTOP state may only be set when returning to |
| 114 | * user space in userret(), or when sleeping interruptably. The |
| 115 | * LSSUSPENDED state may only be set in userret(). Before setting |
| 116 | * those states, we try to ensure that the LWPs will release all |
| 117 | * locks that they hold, and at a minimum try to ensure that the |
| 118 | * LWP can be set runnable again by a signal. |
| 119 | * |
| 120 | * LWPs may transition states in the following ways: |
| 121 | * |
| 122 | * RUN -------> ONPROC ONPROC -----> RUN |
| 123 | * > SLEEP |
| 124 | * > STOPPED |
| 125 | * > SUSPENDED |
| 126 | * > ZOMB |
| 127 | * > IDL (special cases) |
| 128 | * |
| 129 | * STOPPED ---> RUN SUSPENDED --> RUN |
| 130 | * > SLEEP |
| 131 | * |
| 132 | * SLEEP -----> ONPROC IDL --------> RUN |
| 133 | * > RUN > SUSPENDED |
| 134 | * > STOPPED > STOPPED |
| 135 | * > ONPROC (special cases) |
| 136 | * |
| 137 | * Some state transitions are only possible with kernel threads (eg |
| 138 | * ONPROC -> IDL) and happen under tightly controlled circumstances |
| 139 | * free of unwanted side effects. |
| 140 | * |
| 141 | * Migration |
| 142 | * |
| 143 | * Migration of threads from one CPU to another could be performed |
| 144 | * internally by the scheduler via sched_takecpu() or sched_catchlwp() |
| 145 | * functions. The universal lwp_migrate() function should be used for |
| 146 | * any other cases. Subsystems in the kernel must be aware that CPU |
| 147 | * of LWP may change, while it is not locked. |
| 148 | * |
| 149 | * Locking |
| 150 | * |
| 151 | * The majority of fields in 'struct lwp' are covered by a single, |
| 152 | * general spin lock pointed to by lwp::l_mutex. The locks covering |
| 153 | * each field are documented in sys/lwp.h. |
| 154 | * |
| 155 | * State transitions must be made with the LWP's general lock held, |
| 156 | * and may cause the LWP's lock pointer to change. Manipulation of |
| 157 | * the general lock is not performed directly, but through calls to |
| 158 | * lwp_lock(), lwp_unlock() and others. It should be noted that the |
| 159 | * adaptive locks are not allowed to be released while the LWP's lock |
| 160 | * is being held (unlike for other spin-locks). |
| 161 | * |
| 162 | * States and their associated locks: |
| 163 | * |
| 164 | * LSONPROC, LSZOMB: |
| 165 | * |
| 166 | * Always covered by spc_lwplock, which protects running LWPs. |
| 167 | * This is a per-CPU lock and matches lwp::l_cpu. |
| 168 | * |
| 169 | * LSIDL, LSRUN: |
| 170 | * |
| 171 | * Always covered by spc_mutex, which protects the run queues. |
| 172 | * This is a per-CPU lock and matches lwp::l_cpu. |
| 173 | * |
| 174 | * LSSLEEP: |
| 175 | * |
| 176 | * Covered by a lock associated with the sleep queue that the |
| 177 | * LWP resides on. Matches lwp::l_sleepq::sq_mutex. |
| 178 | * |
| 179 | * LSSTOP, LSSUSPENDED: |
| 180 | * |
| 181 | * If the LWP was previously sleeping (l_wchan != NULL), then |
| 182 | * l_mutex references the sleep queue lock. If the LWP was |
| 183 | * runnable or on the CPU when halted, or has been removed from |
| 184 | * the sleep queue since halted, then the lock is spc_lwplock. |
| 185 | * |
| 186 | * The lock order is as follows: |
| 187 | * |
| 188 | * spc::spc_lwplock -> |
| 189 | * sleeptab::st_mutex -> |
| 190 | * tschain_t::tc_mutex -> |
| 191 | * spc::spc_mutex |
| 192 | * |
| 193 | * Each process has an scheduler state lock (proc::p_lock), and a |
| 194 | * number of counters on LWPs and their states: p_nzlwps, p_nrlwps, and |
| 195 | * so on. When an LWP is to be entered into or removed from one of the |
| 196 | * following states, p_lock must be held and the process wide counters |
| 197 | * adjusted: |
| 198 | * |
| 199 | * LSIDL, LSZOMB, LSSTOP, LSSUSPENDED |
| 200 | * |
| 201 | * (But not always for kernel threads. There are some special cases |
| 202 | * as mentioned above. See kern_softint.c.) |
| 203 | * |
| 204 | * Note that an LWP is considered running or likely to run soon if in |
| 205 | * one of the following states. This affects the value of p_nrlwps: |
| 206 | * |
| 207 | * LSRUN, LSONPROC, LSSLEEP |
| 208 | * |
| 209 | * p_lock does not need to be held when transitioning among these |
| 210 | * three states, hence p_lock is rarely taken for state transitions. |
| 211 | */ |
| 212 | |
| 213 | #include <sys/cdefs.h> |
| 214 | __KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.185 2016/07/03 14:24:58 christos Exp $" ); |
| 215 | |
| 216 | #include "opt_ddb.h" |
| 217 | #include "opt_lockdebug.h" |
| 218 | #include "opt_dtrace.h" |
| 219 | |
| 220 | #define _LWP_API_PRIVATE |
| 221 | |
| 222 | #include <sys/param.h> |
| 223 | #include <sys/systm.h> |
| 224 | #include <sys/cpu.h> |
| 225 | #include <sys/pool.h> |
| 226 | #include <sys/proc.h> |
| 227 | #include <sys/syscallargs.h> |
| 228 | #include <sys/syscall_stats.h> |
| 229 | #include <sys/kauth.h> |
| 230 | #include <sys/pserialize.h> |
| 231 | #include <sys/sleepq.h> |
| 232 | #include <sys/lockdebug.h> |
| 233 | #include <sys/kmem.h> |
| 234 | #include <sys/pset.h> |
| 235 | #include <sys/intr.h> |
| 236 | #include <sys/lwpctl.h> |
| 237 | #include <sys/atomic.h> |
| 238 | #include <sys/filedesc.h> |
| 239 | #include <sys/dtrace_bsd.h> |
| 240 | #include <sys/sdt.h> |
| 241 | #include <sys/xcall.h> |
| 242 | #include <sys/uidinfo.h> |
| 243 | #include <sys/sysctl.h> |
| 244 | |
| 245 | #include <uvm/uvm_extern.h> |
| 246 | #include <uvm/uvm_object.h> |
| 247 | |
| 248 | static pool_cache_t lwp_cache __read_mostly; |
| 249 | struct lwplist alllwp __cacheline_aligned; |
| 250 | |
| 251 | static void lwp_dtor(void *, void *); |
| 252 | |
| 253 | /* DTrace proc provider probes */ |
| 254 | SDT_PROVIDER_DEFINE(proc); |
| 255 | |
| 256 | SDT_PROBE_DEFINE1(proc, kernel, , lwp__create, "struct lwp *" ); |
| 257 | SDT_PROBE_DEFINE1(proc, kernel, , lwp__start, "struct lwp *" ); |
| 258 | SDT_PROBE_DEFINE1(proc, kernel, , lwp__exit, "struct lwp *" ); |
| 259 | |
| 260 | struct turnstile turnstile0; |
| 261 | struct lwp lwp0 __aligned(MIN_LWP_ALIGNMENT) = { |
| 262 | #ifdef LWP0_CPU_INFO |
| 263 | .l_cpu = LWP0_CPU_INFO, |
| 264 | #endif |
| 265 | #ifdef LWP0_MD_INITIALIZER |
| 266 | .l_md = LWP0_MD_INITIALIZER, |
| 267 | #endif |
| 268 | .l_proc = &proc0, |
| 269 | .l_lid = 1, |
| 270 | .l_flag = LW_SYSTEM, |
| 271 | .l_stat = LSONPROC, |
| 272 | .l_ts = &turnstile0, |
| 273 | .l_syncobj = &sched_syncobj, |
| 274 | .l_refcnt = 1, |
| 275 | .l_priority = PRI_USER + NPRI_USER - 1, |
| 276 | .l_inheritedprio = -1, |
| 277 | .l_class = SCHED_OTHER, |
| 278 | .l_psid = PS_NONE, |
| 279 | .l_pi_lenders = SLIST_HEAD_INITIALIZER(&lwp0.l_pi_lenders), |
| 280 | .l_name = __UNCONST("swapper" ), |
| 281 | .l_fd = &filedesc0, |
| 282 | }; |
| 283 | |
| 284 | static int sysctl_kern_maxlwp(SYSCTLFN_PROTO); |
| 285 | |
| 286 | /* |
| 287 | * sysctl helper routine for kern.maxlwp. Ensures that the new |
| 288 | * values are not too low or too high. |
| 289 | */ |
| 290 | static int |
| 291 | sysctl_kern_maxlwp(SYSCTLFN_ARGS) |
| 292 | { |
| 293 | int error, nmaxlwp; |
| 294 | struct sysctlnode node; |
| 295 | |
| 296 | nmaxlwp = maxlwp; |
| 297 | node = *rnode; |
| 298 | node.sysctl_data = &nmaxlwp; |
| 299 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 300 | if (error || newp == NULL) |
| 301 | return error; |
| 302 | |
| 303 | if (nmaxlwp < 0 || nmaxlwp >= 65536) |
| 304 | return EINVAL; |
| 305 | if (nmaxlwp > cpu_maxlwp()) |
| 306 | return EINVAL; |
| 307 | maxlwp = nmaxlwp; |
| 308 | |
| 309 | return 0; |
| 310 | } |
| 311 | |
| 312 | static void |
| 313 | sysctl_kern_lwp_setup(void) |
| 314 | { |
| 315 | struct sysctllog *clog = NULL; |
| 316 | |
| 317 | sysctl_createv(&clog, 0, NULL, NULL, |
| 318 | CTLFLAG_PERMANENT|CTLFLAG_READWRITE, |
| 319 | CTLTYPE_INT, "maxlwp" , |
| 320 | SYSCTL_DESCR("Maximum number of simultaneous threads" ), |
| 321 | sysctl_kern_maxlwp, 0, NULL, 0, |
| 322 | CTL_KERN, CTL_CREATE, CTL_EOL); |
| 323 | } |
| 324 | |
| 325 | void |
| 326 | lwpinit(void) |
| 327 | { |
| 328 | |
| 329 | LIST_INIT(&alllwp); |
| 330 | lwpinit_specificdata(); |
| 331 | lwp_sys_init(); |
| 332 | lwp_cache = pool_cache_init(sizeof(lwp_t), MIN_LWP_ALIGNMENT, 0, 0, |
| 333 | "lwppl" , NULL, IPL_NONE, NULL, lwp_dtor, NULL); |
| 334 | |
| 335 | maxlwp = cpu_maxlwp(); |
| 336 | sysctl_kern_lwp_setup(); |
| 337 | } |
| 338 | |
| 339 | void |
| 340 | lwp0_init(void) |
| 341 | { |
| 342 | struct lwp *l = &lwp0; |
| 343 | |
| 344 | KASSERT((void *)uvm_lwp_getuarea(l) != NULL); |
| 345 | KASSERT(l->l_lid == proc0.p_nlwpid); |
| 346 | |
| 347 | LIST_INSERT_HEAD(&alllwp, l, l_list); |
| 348 | |
| 349 | callout_init(&l->l_timeout_ch, CALLOUT_MPSAFE); |
| 350 | callout_setfunc(&l->l_timeout_ch, sleepq_timeout, l); |
| 351 | cv_init(&l->l_sigcv, "sigwait" ); |
| 352 | cv_init(&l->l_waitcv, "vfork" ); |
| 353 | |
| 354 | kauth_cred_hold(proc0.p_cred); |
| 355 | l->l_cred = proc0.p_cred; |
| 356 | |
| 357 | kdtrace_thread_ctor(NULL, l); |
| 358 | lwp_initspecific(l); |
| 359 | |
| 360 | SYSCALL_TIME_LWP_INIT(l); |
| 361 | } |
| 362 | |
| 363 | static void |
| 364 | lwp_dtor(void *arg, void *obj) |
| 365 | { |
| 366 | lwp_t *l = obj; |
| 367 | uint64_t where; |
| 368 | (void)l; |
| 369 | |
| 370 | /* |
| 371 | * Provide a barrier to ensure that all mutex_oncpu() and rw_oncpu() |
| 372 | * calls will exit before memory of LWP is returned to the pool, where |
| 373 | * KVA of LWP structure might be freed and re-used for other purposes. |
| 374 | * Kernel preemption is disabled around mutex_oncpu() and rw_oncpu() |
| 375 | * callers, therefore cross-call to all CPUs will do the job. Also, |
| 376 | * the value of l->l_cpu must be still valid at this point. |
| 377 | */ |
| 378 | KASSERT(l->l_cpu != NULL); |
| 379 | where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL); |
| 380 | xc_wait(where); |
| 381 | } |
| 382 | |
| 383 | /* |
| 384 | * Set an suspended. |
| 385 | * |
| 386 | * Must be called with p_lock held, and the LWP locked. Will unlock the |
| 387 | * LWP before return. |
| 388 | */ |
| 389 | int |
| 390 | lwp_suspend(struct lwp *curl, struct lwp *t) |
| 391 | { |
| 392 | int error; |
| 393 | |
| 394 | KASSERT(mutex_owned(t->l_proc->p_lock)); |
| 395 | KASSERT(lwp_locked(t, NULL)); |
| 396 | |
| 397 | KASSERT(curl != t || curl->l_stat == LSONPROC); |
| 398 | |
| 399 | /* |
| 400 | * If the current LWP has been told to exit, we must not suspend anyone |
| 401 | * else or deadlock could occur. We won't return to userspace. |
| 402 | */ |
| 403 | if ((curl->l_flag & (LW_WEXIT | LW_WCORE)) != 0) { |
| 404 | lwp_unlock(t); |
| 405 | return (EDEADLK); |
| 406 | } |
| 407 | |
| 408 | error = 0; |
| 409 | |
| 410 | switch (t->l_stat) { |
| 411 | case LSRUN: |
| 412 | case LSONPROC: |
| 413 | t->l_flag |= LW_WSUSPEND; |
| 414 | lwp_need_userret(t); |
| 415 | lwp_unlock(t); |
| 416 | break; |
| 417 | |
| 418 | case LSSLEEP: |
| 419 | t->l_flag |= LW_WSUSPEND; |
| 420 | |
| 421 | /* |
| 422 | * Kick the LWP and try to get it to the kernel boundary |
| 423 | * so that it will release any locks that it holds. |
| 424 | * setrunnable() will release the lock. |
| 425 | */ |
| 426 | if ((t->l_flag & LW_SINTR) != 0) |
| 427 | setrunnable(t); |
| 428 | else |
| 429 | lwp_unlock(t); |
| 430 | break; |
| 431 | |
| 432 | case LSSUSPENDED: |
| 433 | lwp_unlock(t); |
| 434 | break; |
| 435 | |
| 436 | case LSSTOP: |
| 437 | t->l_flag |= LW_WSUSPEND; |
| 438 | setrunnable(t); |
| 439 | break; |
| 440 | |
| 441 | case LSIDL: |
| 442 | case LSZOMB: |
| 443 | error = EINTR; /* It's what Solaris does..... */ |
| 444 | lwp_unlock(t); |
| 445 | break; |
| 446 | } |
| 447 | |
| 448 | return (error); |
| 449 | } |
| 450 | |
| 451 | /* |
| 452 | * Restart a suspended LWP. |
| 453 | * |
| 454 | * Must be called with p_lock held, and the LWP locked. Will unlock the |
| 455 | * LWP before return. |
| 456 | */ |
| 457 | void |
| 458 | lwp_continue(struct lwp *l) |
| 459 | { |
| 460 | |
| 461 | KASSERT(mutex_owned(l->l_proc->p_lock)); |
| 462 | KASSERT(lwp_locked(l, NULL)); |
| 463 | |
| 464 | /* If rebooting or not suspended, then just bail out. */ |
| 465 | if ((l->l_flag & LW_WREBOOT) != 0) { |
| 466 | lwp_unlock(l); |
| 467 | return; |
| 468 | } |
| 469 | |
| 470 | l->l_flag &= ~LW_WSUSPEND; |
| 471 | |
| 472 | if (l->l_stat != LSSUSPENDED) { |
| 473 | lwp_unlock(l); |
| 474 | return; |
| 475 | } |
| 476 | |
| 477 | /* setrunnable() will release the lock. */ |
| 478 | setrunnable(l); |
| 479 | } |
| 480 | |
| 481 | /* |
| 482 | * Restart a stopped LWP. |
| 483 | * |
| 484 | * Must be called with p_lock held, and the LWP NOT locked. Will unlock the |
| 485 | * LWP before return. |
| 486 | */ |
| 487 | void |
| 488 | lwp_unstop(struct lwp *l) |
| 489 | { |
| 490 | struct proc *p = l->l_proc; |
| 491 | |
| 492 | KASSERT(mutex_owned(proc_lock)); |
| 493 | KASSERT(mutex_owned(p->p_lock)); |
| 494 | |
| 495 | lwp_lock(l); |
| 496 | |
| 497 | /* If not stopped, then just bail out. */ |
| 498 | if (l->l_stat != LSSTOP) { |
| 499 | lwp_unlock(l); |
| 500 | return; |
| 501 | } |
| 502 | |
| 503 | p->p_stat = SACTIVE; |
| 504 | p->p_sflag &= ~PS_STOPPING; |
| 505 | |
| 506 | if (!p->p_waited) |
| 507 | p->p_pptr->p_nstopchild--; |
| 508 | |
| 509 | if (l->l_wchan == NULL) { |
| 510 | /* setrunnable() will release the lock. */ |
| 511 | setrunnable(l); |
| 512 | } else if (p->p_xsig && (l->l_flag & LW_SINTR) != 0) { |
| 513 | /* setrunnable() so we can receive the signal */ |
| 514 | setrunnable(l); |
| 515 | } else { |
| 516 | l->l_stat = LSSLEEP; |
| 517 | p->p_nrlwps++; |
| 518 | lwp_unlock(l); |
| 519 | } |
| 520 | } |
| 521 | |
| 522 | /* |
| 523 | * Wait for an LWP within the current process to exit. If 'lid' is |
| 524 | * non-zero, we are waiting for a specific LWP. |
| 525 | * |
| 526 | * Must be called with p->p_lock held. |
| 527 | */ |
| 528 | int |
| 529 | lwp_wait(struct lwp *l, lwpid_t lid, lwpid_t *departed, bool exiting) |
| 530 | { |
| 531 | const lwpid_t curlid = l->l_lid; |
| 532 | proc_t *p = l->l_proc; |
| 533 | lwp_t *l2; |
| 534 | int error; |
| 535 | |
| 536 | KASSERT(mutex_owned(p->p_lock)); |
| 537 | |
| 538 | p->p_nlwpwait++; |
| 539 | l->l_waitingfor = lid; |
| 540 | |
| 541 | for (;;) { |
| 542 | int nfound; |
| 543 | |
| 544 | /* |
| 545 | * Avoid a race between exit1() and sigexit(): if the |
| 546 | * process is dumping core, then we need to bail out: call |
| 547 | * into lwp_userret() where we will be suspended until the |
| 548 | * deed is done. |
| 549 | */ |
| 550 | if ((p->p_sflag & PS_WCORE) != 0) { |
| 551 | mutex_exit(p->p_lock); |
| 552 | lwp_userret(l); |
| 553 | KASSERT(false); |
| 554 | } |
| 555 | |
| 556 | /* |
| 557 | * First off, drain any detached LWP that is waiting to be |
| 558 | * reaped. |
| 559 | */ |
| 560 | while ((l2 = p->p_zomblwp) != NULL) { |
| 561 | p->p_zomblwp = NULL; |
| 562 | lwp_free(l2, false, false);/* releases proc mutex */ |
| 563 | mutex_enter(p->p_lock); |
| 564 | } |
| 565 | |
| 566 | /* |
| 567 | * Now look for an LWP to collect. If the whole process is |
| 568 | * exiting, count detached LWPs as eligible to be collected, |
| 569 | * but don't drain them here. |
| 570 | */ |
| 571 | nfound = 0; |
| 572 | error = 0; |
| 573 | LIST_FOREACH(l2, &p->p_lwps, l_sibling) { |
| 574 | /* |
| 575 | * If a specific wait and the target is waiting on |
| 576 | * us, then avoid deadlock. This also traps LWPs |
| 577 | * that try to wait on themselves. |
| 578 | * |
| 579 | * Note that this does not handle more complicated |
| 580 | * cycles, like: t1 -> t2 -> t3 -> t1. The process |
| 581 | * can still be killed so it is not a major problem. |
| 582 | */ |
| 583 | if (l2->l_lid == lid && l2->l_waitingfor == curlid) { |
| 584 | error = EDEADLK; |
| 585 | break; |
| 586 | } |
| 587 | if (l2 == l) |
| 588 | continue; |
| 589 | if ((l2->l_prflag & LPR_DETACHED) != 0) { |
| 590 | nfound += exiting; |
| 591 | continue; |
| 592 | } |
| 593 | if (lid != 0) { |
| 594 | if (l2->l_lid != lid) |
| 595 | continue; |
| 596 | /* |
| 597 | * Mark this LWP as the first waiter, if there |
| 598 | * is no other. |
| 599 | */ |
| 600 | if (l2->l_waiter == 0) |
| 601 | l2->l_waiter = curlid; |
| 602 | } else if (l2->l_waiter != 0) { |
| 603 | /* |
| 604 | * It already has a waiter - so don't |
| 605 | * collect it. If the waiter doesn't |
| 606 | * grab it we'll get another chance |
| 607 | * later. |
| 608 | */ |
| 609 | nfound++; |
| 610 | continue; |
| 611 | } |
| 612 | nfound++; |
| 613 | |
| 614 | /* No need to lock the LWP in order to see LSZOMB. */ |
| 615 | if (l2->l_stat != LSZOMB) |
| 616 | continue; |
| 617 | |
| 618 | /* |
| 619 | * We're no longer waiting. Reset the "first waiter" |
| 620 | * pointer on the target, in case it was us. |
| 621 | */ |
| 622 | l->l_waitingfor = 0; |
| 623 | l2->l_waiter = 0; |
| 624 | p->p_nlwpwait--; |
| 625 | if (departed) |
| 626 | *departed = l2->l_lid; |
| 627 | sched_lwp_collect(l2); |
| 628 | |
| 629 | /* lwp_free() releases the proc lock. */ |
| 630 | lwp_free(l2, false, false); |
| 631 | mutex_enter(p->p_lock); |
| 632 | return 0; |
| 633 | } |
| 634 | |
| 635 | if (error != 0) |
| 636 | break; |
| 637 | if (nfound == 0) { |
| 638 | error = ESRCH; |
| 639 | break; |
| 640 | } |
| 641 | |
| 642 | /* |
| 643 | * Note: since the lock will be dropped, need to restart on |
| 644 | * wakeup to run all LWPs again, e.g. there may be new LWPs. |
| 645 | */ |
| 646 | if (exiting) { |
| 647 | KASSERT(p->p_nlwps > 1); |
| 648 | cv_wait(&p->p_lwpcv, p->p_lock); |
| 649 | error = EAGAIN; |
| 650 | break; |
| 651 | } |
| 652 | |
| 653 | /* |
| 654 | * If all other LWPs are waiting for exits or suspends |
| 655 | * and the supply of zombies and potential zombies is |
| 656 | * exhausted, then we are about to deadlock. |
| 657 | * |
| 658 | * If the process is exiting (and this LWP is not the one |
| 659 | * that is coordinating the exit) then bail out now. |
| 660 | */ |
| 661 | if ((p->p_sflag & PS_WEXIT) != 0 || |
| 662 | p->p_nrlwps + p->p_nzlwps - p->p_ndlwps <= p->p_nlwpwait) { |
| 663 | error = EDEADLK; |
| 664 | break; |
| 665 | } |
| 666 | |
| 667 | /* |
| 668 | * Sit around and wait for something to happen. We'll be |
| 669 | * awoken if any of the conditions examined change: if an |
| 670 | * LWP exits, is collected, or is detached. |
| 671 | */ |
| 672 | if ((error = cv_wait_sig(&p->p_lwpcv, p->p_lock)) != 0) |
| 673 | break; |
| 674 | } |
| 675 | |
| 676 | /* |
| 677 | * We didn't find any LWPs to collect, we may have received a |
| 678 | * signal, or some other condition has caused us to bail out. |
| 679 | * |
| 680 | * If waiting on a specific LWP, clear the waiters marker: some |
| 681 | * other LWP may want it. Then, kick all the remaining waiters |
| 682 | * so that they can re-check for zombies and for deadlock. |
| 683 | */ |
| 684 | if (lid != 0) { |
| 685 | LIST_FOREACH(l2, &p->p_lwps, l_sibling) { |
| 686 | if (l2->l_lid == lid) { |
| 687 | if (l2->l_waiter == curlid) |
| 688 | l2->l_waiter = 0; |
| 689 | break; |
| 690 | } |
| 691 | } |
| 692 | } |
| 693 | p->p_nlwpwait--; |
| 694 | l->l_waitingfor = 0; |
| 695 | cv_broadcast(&p->p_lwpcv); |
| 696 | |
| 697 | return error; |
| 698 | } |
| 699 | |
| 700 | static lwpid_t |
| 701 | lwp_find_free_lid(lwpid_t try_lid, lwp_t * new_lwp, proc_t *p) |
| 702 | { |
| 703 | #define LID_SCAN (1u << 31) |
| 704 | lwp_t *scan, *free_before; |
| 705 | lwpid_t nxt_lid; |
| 706 | |
| 707 | /* |
| 708 | * We want the first unused lid greater than or equal to |
| 709 | * try_lid (modulo 2^31). |
| 710 | * (If nothing else ld.elf_so doesn't want lwpid with the top bit set.) |
| 711 | * We must not return 0, and avoiding 'LID_SCAN - 1' makes |
| 712 | * the outer test easier. |
| 713 | * This would be much easier if the list were sorted in |
| 714 | * increasing order. |
| 715 | * The list is kept sorted in decreasing order. |
| 716 | * This code is only used after a process has generated 2^31 lwp. |
| 717 | * |
| 718 | * Code assumes it can always find an id. |
| 719 | */ |
| 720 | |
| 721 | try_lid &= LID_SCAN - 1; |
| 722 | if (try_lid <= 1) |
| 723 | try_lid = 2; |
| 724 | |
| 725 | free_before = NULL; |
| 726 | nxt_lid = LID_SCAN - 1; |
| 727 | LIST_FOREACH(scan, &p->p_lwps, l_sibling) { |
| 728 | if (scan->l_lid != nxt_lid) { |
| 729 | /* There are available lid before this entry */ |
| 730 | free_before = scan; |
| 731 | if (try_lid > scan->l_lid) |
| 732 | break; |
| 733 | } |
| 734 | if (try_lid == scan->l_lid) { |
| 735 | /* The ideal lid is busy, take a higher one */ |
| 736 | if (free_before != NULL) { |
| 737 | try_lid = free_before->l_lid + 1; |
| 738 | break; |
| 739 | } |
| 740 | /* No higher ones, reuse low numbers */ |
| 741 | try_lid = 2; |
| 742 | } |
| 743 | |
| 744 | nxt_lid = scan->l_lid - 1; |
| 745 | if (LIST_NEXT(scan, l_sibling) == NULL) { |
| 746 | /* The value we have is lower than any existing lwp */ |
| 747 | LIST_INSERT_AFTER(scan, new_lwp, l_sibling); |
| 748 | return try_lid; |
| 749 | } |
| 750 | } |
| 751 | |
| 752 | LIST_INSERT_BEFORE(free_before, new_lwp, l_sibling); |
| 753 | return try_lid; |
| 754 | } |
| 755 | |
| 756 | /* |
| 757 | * Create a new LWP within process 'p2', using LWP 'l1' as a template. |
| 758 | * The new LWP is created in state LSIDL and must be set running, |
| 759 | * suspended, or stopped by the caller. |
| 760 | */ |
| 761 | int |
| 762 | lwp_create(lwp_t *l1, proc_t *p2, vaddr_t uaddr, int flags, |
| 763 | void *stack, size_t stacksize, void (*func)(void *), void *arg, |
| 764 | lwp_t **rnewlwpp, int sclass) |
| 765 | { |
| 766 | struct lwp *l2, *isfree; |
| 767 | turnstile_t *ts; |
| 768 | lwpid_t lid; |
| 769 | |
| 770 | KASSERT(l1 == curlwp || l1->l_proc == &proc0); |
| 771 | |
| 772 | /* |
| 773 | * Enforce limits, excluding the first lwp and kthreads. |
| 774 | */ |
| 775 | if (p2->p_nlwps != 0 && p2 != &proc0) { |
| 776 | uid_t uid = kauth_cred_getuid(l1->l_cred); |
| 777 | int count = chglwpcnt(uid, 1); |
| 778 | if (__predict_false(count > |
| 779 | p2->p_rlimit[RLIMIT_NTHR].rlim_cur)) { |
| 780 | if (kauth_authorize_process(l1->l_cred, |
| 781 | KAUTH_PROCESS_RLIMIT, p2, |
| 782 | KAUTH_ARG(KAUTH_REQ_PROCESS_RLIMIT_BYPASS), |
| 783 | &p2->p_rlimit[RLIMIT_NTHR], KAUTH_ARG(RLIMIT_NTHR)) |
| 784 | != 0) { |
| 785 | (void)chglwpcnt(uid, -1); |
| 786 | return EAGAIN; |
| 787 | } |
| 788 | } |
| 789 | } |
| 790 | |
| 791 | /* |
| 792 | * First off, reap any detached LWP waiting to be collected. |
| 793 | * We can re-use its LWP structure and turnstile. |
| 794 | */ |
| 795 | isfree = NULL; |
| 796 | if (p2->p_zomblwp != NULL) { |
| 797 | mutex_enter(p2->p_lock); |
| 798 | if ((isfree = p2->p_zomblwp) != NULL) { |
| 799 | p2->p_zomblwp = NULL; |
| 800 | lwp_free(isfree, true, false);/* releases proc mutex */ |
| 801 | } else |
| 802 | mutex_exit(p2->p_lock); |
| 803 | } |
| 804 | if (isfree == NULL) { |
| 805 | l2 = pool_cache_get(lwp_cache, PR_WAITOK); |
| 806 | memset(l2, 0, sizeof(*l2)); |
| 807 | l2->l_ts = pool_cache_get(turnstile_cache, PR_WAITOK); |
| 808 | SLIST_INIT(&l2->l_pi_lenders); |
| 809 | } else { |
| 810 | l2 = isfree; |
| 811 | ts = l2->l_ts; |
| 812 | KASSERT(l2->l_inheritedprio == -1); |
| 813 | KASSERT(SLIST_EMPTY(&l2->l_pi_lenders)); |
| 814 | memset(l2, 0, sizeof(*l2)); |
| 815 | l2->l_ts = ts; |
| 816 | } |
| 817 | |
| 818 | l2->l_stat = LSIDL; |
| 819 | l2->l_proc = p2; |
| 820 | l2->l_refcnt = 1; |
| 821 | l2->l_class = sclass; |
| 822 | |
| 823 | /* |
| 824 | * If vfork(), we want the LWP to run fast and on the same CPU |
| 825 | * as its parent, so that it can reuse the VM context and cache |
| 826 | * footprint on the local CPU. |
| 827 | */ |
| 828 | l2->l_kpriority = ((flags & LWP_VFORK) ? true : false); |
| 829 | l2->l_kpribase = PRI_KERNEL; |
| 830 | l2->l_priority = l1->l_priority; |
| 831 | l2->l_inheritedprio = -1; |
| 832 | l2->l_protectprio = -1; |
| 833 | l2->l_auxprio = -1; |
| 834 | l2->l_flag = 0; |
| 835 | l2->l_pflag = LP_MPSAFE; |
| 836 | TAILQ_INIT(&l2->l_ld_locks); |
| 837 | |
| 838 | /* |
| 839 | * For vfork, borrow parent's lwpctl context if it exists. |
| 840 | * This also causes us to return via lwp_userret. |
| 841 | */ |
| 842 | if (flags & LWP_VFORK && l1->l_lwpctl) { |
| 843 | l2->l_lwpctl = l1->l_lwpctl; |
| 844 | l2->l_flag |= LW_LWPCTL; |
| 845 | } |
| 846 | |
| 847 | /* |
| 848 | * If not the first LWP in the process, grab a reference to the |
| 849 | * descriptor table. |
| 850 | */ |
| 851 | l2->l_fd = p2->p_fd; |
| 852 | if (p2->p_nlwps != 0) { |
| 853 | KASSERT(l1->l_proc == p2); |
| 854 | fd_hold(l2); |
| 855 | } else { |
| 856 | KASSERT(l1->l_proc != p2); |
| 857 | } |
| 858 | |
| 859 | if (p2->p_flag & PK_SYSTEM) { |
| 860 | /* Mark it as a system LWP. */ |
| 861 | l2->l_flag |= LW_SYSTEM; |
| 862 | } |
| 863 | |
| 864 | kpreempt_disable(); |
| 865 | l2->l_mutex = l1->l_cpu->ci_schedstate.spc_mutex; |
| 866 | l2->l_cpu = l1->l_cpu; |
| 867 | kpreempt_enable(); |
| 868 | |
| 869 | kdtrace_thread_ctor(NULL, l2); |
| 870 | lwp_initspecific(l2); |
| 871 | sched_lwp_fork(l1, l2); |
| 872 | lwp_update_creds(l2); |
| 873 | callout_init(&l2->l_timeout_ch, CALLOUT_MPSAFE); |
| 874 | callout_setfunc(&l2->l_timeout_ch, sleepq_timeout, l2); |
| 875 | cv_init(&l2->l_sigcv, "sigwait" ); |
| 876 | cv_init(&l2->l_waitcv, "vfork" ); |
| 877 | l2->l_syncobj = &sched_syncobj; |
| 878 | |
| 879 | if (rnewlwpp != NULL) |
| 880 | *rnewlwpp = l2; |
| 881 | |
| 882 | /* |
| 883 | * PCU state needs to be saved before calling uvm_lwp_fork() so that |
| 884 | * the MD cpu_lwp_fork() can copy the saved state to the new LWP. |
| 885 | */ |
| 886 | pcu_save_all(l1); |
| 887 | |
| 888 | uvm_lwp_setuarea(l2, uaddr); |
| 889 | uvm_lwp_fork(l1, l2, stack, stacksize, func, |
| 890 | (arg != NULL) ? arg : l2); |
| 891 | |
| 892 | if ((flags & LWP_PIDLID) != 0) { |
| 893 | lid = proc_alloc_pid(p2); |
| 894 | l2->l_pflag |= LP_PIDLID; |
| 895 | } else { |
| 896 | lid = 0; |
| 897 | } |
| 898 | |
| 899 | mutex_enter(p2->p_lock); |
| 900 | |
| 901 | if ((flags & LWP_DETACHED) != 0) { |
| 902 | l2->l_prflag = LPR_DETACHED; |
| 903 | p2->p_ndlwps++; |
| 904 | } else |
| 905 | l2->l_prflag = 0; |
| 906 | |
| 907 | l2->l_sigstk = l1->l_sigstk; |
| 908 | l2->l_sigmask = l1->l_sigmask; |
| 909 | TAILQ_INIT(&l2->l_sigpend.sp_info); |
| 910 | sigemptyset(&l2->l_sigpend.sp_set); |
| 911 | |
| 912 | if (__predict_true(lid == 0)) { |
| 913 | /* |
| 914 | * XXX: l_lid are expected to be unique (for a process) |
| 915 | * if LWP_PIDLID is sometimes set this won't be true. |
| 916 | * Once 2^31 threads have been allocated we have to |
| 917 | * scan to ensure we allocate a unique value. |
| 918 | */ |
| 919 | lid = ++p2->p_nlwpid; |
| 920 | if (__predict_false(lid & LID_SCAN)) { |
| 921 | lid = lwp_find_free_lid(lid, l2, p2); |
| 922 | p2->p_nlwpid = lid | LID_SCAN; |
| 923 | /* l2 as been inserted into p_lwps in order */ |
| 924 | goto skip_insert; |
| 925 | } |
| 926 | p2->p_nlwpid = lid; |
| 927 | } |
| 928 | LIST_INSERT_HEAD(&p2->p_lwps, l2, l_sibling); |
| 929 | skip_insert: |
| 930 | l2->l_lid = lid; |
| 931 | p2->p_nlwps++; |
| 932 | p2->p_nrlwps++; |
| 933 | |
| 934 | KASSERT(l2->l_affinity == NULL); |
| 935 | |
| 936 | if ((p2->p_flag & PK_SYSTEM) == 0) { |
| 937 | /* Inherit the affinity mask. */ |
| 938 | if (l1->l_affinity) { |
| 939 | /* |
| 940 | * Note that we hold the state lock while inheriting |
| 941 | * the affinity to avoid race with sched_setaffinity(). |
| 942 | */ |
| 943 | lwp_lock(l1); |
| 944 | if (l1->l_affinity) { |
| 945 | kcpuset_use(l1->l_affinity); |
| 946 | l2->l_affinity = l1->l_affinity; |
| 947 | } |
| 948 | lwp_unlock(l1); |
| 949 | } |
| 950 | lwp_lock(l2); |
| 951 | /* Inherit a processor-set */ |
| 952 | l2->l_psid = l1->l_psid; |
| 953 | /* Look for a CPU to start */ |
| 954 | l2->l_cpu = sched_takecpu(l2); |
| 955 | lwp_unlock_to(l2, l2->l_cpu->ci_schedstate.spc_mutex); |
| 956 | } |
| 957 | mutex_exit(p2->p_lock); |
| 958 | |
| 959 | SDT_PROBE(proc, kernel, , lwp__create, l2, 0, 0, 0, 0); |
| 960 | |
| 961 | mutex_enter(proc_lock); |
| 962 | LIST_INSERT_HEAD(&alllwp, l2, l_list); |
| 963 | mutex_exit(proc_lock); |
| 964 | |
| 965 | SYSCALL_TIME_LWP_INIT(l2); |
| 966 | |
| 967 | if (p2->p_emul->e_lwp_fork) |
| 968 | (*p2->p_emul->e_lwp_fork)(l1, l2); |
| 969 | |
| 970 | return (0); |
| 971 | } |
| 972 | |
| 973 | /* |
| 974 | * Called by MD code when a new LWP begins execution. Must be called |
| 975 | * with the previous LWP locked (so at splsched), or if there is no |
| 976 | * previous LWP, at splsched. |
| 977 | */ |
| 978 | void |
| 979 | lwp_startup(struct lwp *prev, struct lwp *new_lwp) |
| 980 | { |
| 981 | KASSERTMSG(new_lwp == curlwp, "l %p curlwp %p prevlwp %p" , new_lwp, curlwp, prev); |
| 982 | |
| 983 | SDT_PROBE(proc, kernel, , lwp__start, new_lwp, 0, 0, 0, 0); |
| 984 | |
| 985 | KASSERT(kpreempt_disabled()); |
| 986 | if (prev != NULL) { |
| 987 | /* |
| 988 | * Normalize the count of the spin-mutexes, it was |
| 989 | * increased in mi_switch(). Unmark the state of |
| 990 | * context switch - it is finished for previous LWP. |
| 991 | */ |
| 992 | curcpu()->ci_mtx_count++; |
| 993 | membar_exit(); |
| 994 | prev->l_ctxswtch = 0; |
| 995 | } |
| 996 | KPREEMPT_DISABLE(new_lwp); |
| 997 | if (__predict_true(new_lwp->l_proc->p_vmspace)) |
| 998 | pmap_activate(new_lwp); |
| 999 | spl0(); |
| 1000 | |
| 1001 | /* Note trip through cpu_switchto(). */ |
| 1002 | pserialize_switchpoint(); |
| 1003 | |
| 1004 | LOCKDEBUG_BARRIER(NULL, 0); |
| 1005 | KPREEMPT_ENABLE(new_lwp); |
| 1006 | if ((new_lwp->l_pflag & LP_MPSAFE) == 0) { |
| 1007 | KERNEL_LOCK(1, new_lwp); |
| 1008 | } |
| 1009 | } |
| 1010 | |
| 1011 | /* |
| 1012 | * Exit an LWP. |
| 1013 | */ |
| 1014 | void |
| 1015 | lwp_exit(struct lwp *l) |
| 1016 | { |
| 1017 | struct proc *p = l->l_proc; |
| 1018 | struct lwp *l2; |
| 1019 | bool current; |
| 1020 | |
| 1021 | current = (l == curlwp); |
| 1022 | |
| 1023 | KASSERT(current || (l->l_stat == LSIDL && l->l_target_cpu == NULL)); |
| 1024 | KASSERT(p == curproc); |
| 1025 | |
| 1026 | SDT_PROBE(proc, kernel, , lwp__exit, l, 0, 0, 0, 0); |
| 1027 | |
| 1028 | /* |
| 1029 | * Verify that we hold no locks other than the kernel lock. |
| 1030 | */ |
| 1031 | LOCKDEBUG_BARRIER(&kernel_lock, 0); |
| 1032 | |
| 1033 | /* |
| 1034 | * If we are the last live LWP in a process, we need to exit the |
| 1035 | * entire process. We do so with an exit status of zero, because |
| 1036 | * it's a "controlled" exit, and because that's what Solaris does. |
| 1037 | * |
| 1038 | * We are not quite a zombie yet, but for accounting purposes we |
| 1039 | * must increment the count of zombies here. |
| 1040 | * |
| 1041 | * Note: the last LWP's specificdata will be deleted here. |
| 1042 | */ |
| 1043 | mutex_enter(p->p_lock); |
| 1044 | if (p->p_nlwps - p->p_nzlwps == 1) { |
| 1045 | KASSERT(current == true); |
| 1046 | KASSERT(p != &proc0); |
| 1047 | /* XXXSMP kernel_lock not held */ |
| 1048 | exit1(l, 0, 0); |
| 1049 | /* NOTREACHED */ |
| 1050 | } |
| 1051 | p->p_nzlwps++; |
| 1052 | mutex_exit(p->p_lock); |
| 1053 | |
| 1054 | if (p->p_emul->e_lwp_exit) |
| 1055 | (*p->p_emul->e_lwp_exit)(l); |
| 1056 | |
| 1057 | /* Drop filedesc reference. */ |
| 1058 | fd_free(); |
| 1059 | |
| 1060 | /* Delete the specificdata while it's still safe to sleep. */ |
| 1061 | lwp_finispecific(l); |
| 1062 | |
| 1063 | /* |
| 1064 | * Release our cached credentials. |
| 1065 | */ |
| 1066 | kauth_cred_free(l->l_cred); |
| 1067 | callout_destroy(&l->l_timeout_ch); |
| 1068 | |
| 1069 | /* |
| 1070 | * Remove the LWP from the global list. |
| 1071 | * Free its LID from the PID namespace if needed. |
| 1072 | */ |
| 1073 | mutex_enter(proc_lock); |
| 1074 | LIST_REMOVE(l, l_list); |
| 1075 | if ((l->l_pflag & LP_PIDLID) != 0 && l->l_lid != p->p_pid) { |
| 1076 | proc_free_pid(l->l_lid); |
| 1077 | } |
| 1078 | mutex_exit(proc_lock); |
| 1079 | |
| 1080 | /* |
| 1081 | * Get rid of all references to the LWP that others (e.g. procfs) |
| 1082 | * may have, and mark the LWP as a zombie. If the LWP is detached, |
| 1083 | * mark it waiting for collection in the proc structure. Note that |
| 1084 | * before we can do that, we need to free any other dead, deatched |
| 1085 | * LWP waiting to meet its maker. |
| 1086 | */ |
| 1087 | mutex_enter(p->p_lock); |
| 1088 | lwp_drainrefs(l); |
| 1089 | |
| 1090 | if ((l->l_prflag & LPR_DETACHED) != 0) { |
| 1091 | while ((l2 = p->p_zomblwp) != NULL) { |
| 1092 | p->p_zomblwp = NULL; |
| 1093 | lwp_free(l2, false, false);/* releases proc mutex */ |
| 1094 | mutex_enter(p->p_lock); |
| 1095 | l->l_refcnt++; |
| 1096 | lwp_drainrefs(l); |
| 1097 | } |
| 1098 | p->p_zomblwp = l; |
| 1099 | } |
| 1100 | |
| 1101 | /* |
| 1102 | * If we find a pending signal for the process and we have been |
| 1103 | * asked to check for signals, then we lose: arrange to have |
| 1104 | * all other LWPs in the process check for signals. |
| 1105 | */ |
| 1106 | if ((l->l_flag & LW_PENDSIG) != 0 && |
| 1107 | firstsig(&p->p_sigpend.sp_set) != 0) { |
| 1108 | LIST_FOREACH(l2, &p->p_lwps, l_sibling) { |
| 1109 | lwp_lock(l2); |
| 1110 | l2->l_flag |= LW_PENDSIG; |
| 1111 | lwp_unlock(l2); |
| 1112 | } |
| 1113 | } |
| 1114 | |
| 1115 | /* |
| 1116 | * Release any PCU resources before becoming a zombie. |
| 1117 | */ |
| 1118 | pcu_discard_all(l); |
| 1119 | |
| 1120 | lwp_lock(l); |
| 1121 | l->l_stat = LSZOMB; |
| 1122 | if (l->l_name != NULL) { |
| 1123 | strcpy(l->l_name, "(zombie)" ); |
| 1124 | } |
| 1125 | lwp_unlock(l); |
| 1126 | p->p_nrlwps--; |
| 1127 | cv_broadcast(&p->p_lwpcv); |
| 1128 | if (l->l_lwpctl != NULL) |
| 1129 | l->l_lwpctl->lc_curcpu = LWPCTL_CPU_EXITED; |
| 1130 | mutex_exit(p->p_lock); |
| 1131 | |
| 1132 | /* |
| 1133 | * We can no longer block. At this point, lwp_free() may already |
| 1134 | * be gunning for us. On a multi-CPU system, we may be off p_lwps. |
| 1135 | * |
| 1136 | * Free MD LWP resources. |
| 1137 | */ |
| 1138 | cpu_lwp_free(l, 0); |
| 1139 | |
| 1140 | if (current) { |
| 1141 | pmap_deactivate(l); |
| 1142 | |
| 1143 | /* |
| 1144 | * Release the kernel lock, and switch away into |
| 1145 | * oblivion. |
| 1146 | */ |
| 1147 | #ifdef notyet |
| 1148 | /* XXXSMP hold in lwp_userret() */ |
| 1149 | KERNEL_UNLOCK_LAST(l); |
| 1150 | #else |
| 1151 | KERNEL_UNLOCK_ALL(l, NULL); |
| 1152 | #endif |
| 1153 | lwp_exit_switchaway(l); |
| 1154 | } |
| 1155 | } |
| 1156 | |
| 1157 | /* |
| 1158 | * Free a dead LWP's remaining resources. |
| 1159 | * |
| 1160 | * XXXLWP limits. |
| 1161 | */ |
| 1162 | void |
| 1163 | lwp_free(struct lwp *l, bool recycle, bool last) |
| 1164 | { |
| 1165 | struct proc *p = l->l_proc; |
| 1166 | struct rusage *ru; |
| 1167 | ksiginfoq_t kq; |
| 1168 | |
| 1169 | KASSERT(l != curlwp); |
| 1170 | KASSERT(last || mutex_owned(p->p_lock)); |
| 1171 | |
| 1172 | /* |
| 1173 | * We use the process credentials instead of the lwp credentials here |
| 1174 | * because the lwp credentials maybe cached (just after a setuid call) |
| 1175 | * and we don't want pay for syncing, since the lwp is going away |
| 1176 | * anyway |
| 1177 | */ |
| 1178 | if (p != &proc0 && p->p_nlwps != 1) |
| 1179 | (void)chglwpcnt(kauth_cred_getuid(p->p_cred), -1); |
| 1180 | /* |
| 1181 | * If this was not the last LWP in the process, then adjust |
| 1182 | * counters and unlock. |
| 1183 | */ |
| 1184 | if (!last) { |
| 1185 | /* |
| 1186 | * Add the LWP's run time to the process' base value. |
| 1187 | * This needs to co-incide with coming off p_lwps. |
| 1188 | */ |
| 1189 | bintime_add(&p->p_rtime, &l->l_rtime); |
| 1190 | p->p_pctcpu += l->l_pctcpu; |
| 1191 | ru = &p->p_stats->p_ru; |
| 1192 | ruadd(ru, &l->l_ru); |
| 1193 | ru->ru_nvcsw += (l->l_ncsw - l->l_nivcsw); |
| 1194 | ru->ru_nivcsw += l->l_nivcsw; |
| 1195 | LIST_REMOVE(l, l_sibling); |
| 1196 | p->p_nlwps--; |
| 1197 | p->p_nzlwps--; |
| 1198 | if ((l->l_prflag & LPR_DETACHED) != 0) |
| 1199 | p->p_ndlwps--; |
| 1200 | |
| 1201 | /* |
| 1202 | * Have any LWPs sleeping in lwp_wait() recheck for |
| 1203 | * deadlock. |
| 1204 | */ |
| 1205 | cv_broadcast(&p->p_lwpcv); |
| 1206 | mutex_exit(p->p_lock); |
| 1207 | } |
| 1208 | |
| 1209 | #ifdef MULTIPROCESSOR |
| 1210 | /* |
| 1211 | * In the unlikely event that the LWP is still on the CPU, |
| 1212 | * then spin until it has switched away. We need to release |
| 1213 | * all locks to avoid deadlock against interrupt handlers on |
| 1214 | * the target CPU. |
| 1215 | */ |
| 1216 | if ((l->l_pflag & LP_RUNNING) != 0 || l->l_cpu->ci_curlwp == l) { |
| 1217 | int count; |
| 1218 | (void)count; /* XXXgcc */ |
| 1219 | KERNEL_UNLOCK_ALL(curlwp, &count); |
| 1220 | while ((l->l_pflag & LP_RUNNING) != 0 || |
| 1221 | l->l_cpu->ci_curlwp == l) |
| 1222 | SPINLOCK_BACKOFF_HOOK; |
| 1223 | KERNEL_LOCK(count, curlwp); |
| 1224 | } |
| 1225 | #endif |
| 1226 | |
| 1227 | /* |
| 1228 | * Destroy the LWP's remaining signal information. |
| 1229 | */ |
| 1230 | ksiginfo_queue_init(&kq); |
| 1231 | sigclear(&l->l_sigpend, NULL, &kq); |
| 1232 | ksiginfo_queue_drain(&kq); |
| 1233 | cv_destroy(&l->l_sigcv); |
| 1234 | cv_destroy(&l->l_waitcv); |
| 1235 | |
| 1236 | /* |
| 1237 | * Free lwpctl structure and affinity. |
| 1238 | */ |
| 1239 | if (l->l_lwpctl) { |
| 1240 | lwp_ctl_free(l); |
| 1241 | } |
| 1242 | if (l->l_affinity) { |
| 1243 | kcpuset_unuse(l->l_affinity, NULL); |
| 1244 | l->l_affinity = NULL; |
| 1245 | } |
| 1246 | |
| 1247 | /* |
| 1248 | * Free the LWP's turnstile and the LWP structure itself unless the |
| 1249 | * caller wants to recycle them. Also, free the scheduler specific |
| 1250 | * data. |
| 1251 | * |
| 1252 | * We can't return turnstile0 to the pool (it didn't come from it), |
| 1253 | * so if it comes up just drop it quietly and move on. |
| 1254 | * |
| 1255 | * We don't recycle the VM resources at this time. |
| 1256 | */ |
| 1257 | |
| 1258 | if (!recycle && l->l_ts != &turnstile0) |
| 1259 | pool_cache_put(turnstile_cache, l->l_ts); |
| 1260 | if (l->l_name != NULL) |
| 1261 | kmem_free(l->l_name, MAXCOMLEN); |
| 1262 | |
| 1263 | cpu_lwp_free2(l); |
| 1264 | uvm_lwp_exit(l); |
| 1265 | |
| 1266 | KASSERT(SLIST_EMPTY(&l->l_pi_lenders)); |
| 1267 | KASSERT(l->l_inheritedprio == -1); |
| 1268 | KASSERT(l->l_blcnt == 0); |
| 1269 | kdtrace_thread_dtor(NULL, l); |
| 1270 | if (!recycle) |
| 1271 | pool_cache_put(lwp_cache, l); |
| 1272 | } |
| 1273 | |
| 1274 | /* |
| 1275 | * Migrate the LWP to the another CPU. Unlocks the LWP. |
| 1276 | */ |
| 1277 | void |
| 1278 | lwp_migrate(lwp_t *l, struct cpu_info *tci) |
| 1279 | { |
| 1280 | struct schedstate_percpu *tspc; |
| 1281 | int lstat = l->l_stat; |
| 1282 | |
| 1283 | KASSERT(lwp_locked(l, NULL)); |
| 1284 | KASSERT(tci != NULL); |
| 1285 | |
| 1286 | /* If LWP is still on the CPU, it must be handled like LSONPROC */ |
| 1287 | if ((l->l_pflag & LP_RUNNING) != 0) { |
| 1288 | lstat = LSONPROC; |
| 1289 | } |
| 1290 | |
| 1291 | /* |
| 1292 | * The destination CPU could be changed while previous migration |
| 1293 | * was not finished. |
| 1294 | */ |
| 1295 | if (l->l_target_cpu != NULL) { |
| 1296 | l->l_target_cpu = tci; |
| 1297 | lwp_unlock(l); |
| 1298 | return; |
| 1299 | } |
| 1300 | |
| 1301 | /* Nothing to do if trying to migrate to the same CPU */ |
| 1302 | if (l->l_cpu == tci) { |
| 1303 | lwp_unlock(l); |
| 1304 | return; |
| 1305 | } |
| 1306 | |
| 1307 | KASSERT(l->l_target_cpu == NULL); |
| 1308 | tspc = &tci->ci_schedstate; |
| 1309 | switch (lstat) { |
| 1310 | case LSRUN: |
| 1311 | l->l_target_cpu = tci; |
| 1312 | break; |
| 1313 | case LSIDL: |
| 1314 | l->l_cpu = tci; |
| 1315 | lwp_unlock_to(l, tspc->spc_mutex); |
| 1316 | return; |
| 1317 | case LSSLEEP: |
| 1318 | l->l_cpu = tci; |
| 1319 | break; |
| 1320 | case LSSTOP: |
| 1321 | case LSSUSPENDED: |
| 1322 | l->l_cpu = tci; |
| 1323 | if (l->l_wchan == NULL) { |
| 1324 | lwp_unlock_to(l, tspc->spc_lwplock); |
| 1325 | return; |
| 1326 | } |
| 1327 | break; |
| 1328 | case LSONPROC: |
| 1329 | l->l_target_cpu = tci; |
| 1330 | spc_lock(l->l_cpu); |
| 1331 | cpu_need_resched(l->l_cpu, RESCHED_KPREEMPT); |
| 1332 | spc_unlock(l->l_cpu); |
| 1333 | break; |
| 1334 | } |
| 1335 | lwp_unlock(l); |
| 1336 | } |
| 1337 | |
| 1338 | /* |
| 1339 | * Find the LWP in the process. Arguments may be zero, in such case, |
| 1340 | * the calling process and first LWP in the list will be used. |
| 1341 | * On success - returns proc locked. |
| 1342 | */ |
| 1343 | struct lwp * |
| 1344 | lwp_find2(pid_t pid, lwpid_t lid) |
| 1345 | { |
| 1346 | proc_t *p; |
| 1347 | lwp_t *l; |
| 1348 | |
| 1349 | /* Find the process. */ |
| 1350 | if (pid != 0) { |
| 1351 | mutex_enter(proc_lock); |
| 1352 | p = proc_find(pid); |
| 1353 | if (p == NULL) { |
| 1354 | mutex_exit(proc_lock); |
| 1355 | return NULL; |
| 1356 | } |
| 1357 | mutex_enter(p->p_lock); |
| 1358 | mutex_exit(proc_lock); |
| 1359 | } else { |
| 1360 | p = curlwp->l_proc; |
| 1361 | mutex_enter(p->p_lock); |
| 1362 | } |
| 1363 | /* Find the thread. */ |
| 1364 | if (lid != 0) { |
| 1365 | l = lwp_find(p, lid); |
| 1366 | } else { |
| 1367 | l = LIST_FIRST(&p->p_lwps); |
| 1368 | } |
| 1369 | if (l == NULL) { |
| 1370 | mutex_exit(p->p_lock); |
| 1371 | } |
| 1372 | return l; |
| 1373 | } |
| 1374 | |
| 1375 | /* |
| 1376 | * Look up a live LWP within the specified process. |
| 1377 | * |
| 1378 | * Must be called with p->p_lock held. |
| 1379 | */ |
| 1380 | struct lwp * |
| 1381 | lwp_find(struct proc *p, lwpid_t id) |
| 1382 | { |
| 1383 | struct lwp *l; |
| 1384 | |
| 1385 | KASSERT(mutex_owned(p->p_lock)); |
| 1386 | |
| 1387 | LIST_FOREACH(l, &p->p_lwps, l_sibling) { |
| 1388 | if (l->l_lid == id) |
| 1389 | break; |
| 1390 | } |
| 1391 | |
| 1392 | /* |
| 1393 | * No need to lock - all of these conditions will |
| 1394 | * be visible with the process level mutex held. |
| 1395 | */ |
| 1396 | if (l != NULL && (l->l_stat == LSIDL || l->l_stat == LSZOMB)) |
| 1397 | l = NULL; |
| 1398 | |
| 1399 | return l; |
| 1400 | } |
| 1401 | |
| 1402 | /* |
| 1403 | * Update an LWP's cached credentials to mirror the process' master copy. |
| 1404 | * |
| 1405 | * This happens early in the syscall path, on user trap, and on LWP |
| 1406 | * creation. A long-running LWP can also voluntarily choose to update |
| 1407 | * its credentials by calling this routine. This may be called from |
| 1408 | * LWP_CACHE_CREDS(), which checks l->l_cred != p->p_cred beforehand. |
| 1409 | */ |
| 1410 | void |
| 1411 | lwp_update_creds(struct lwp *l) |
| 1412 | { |
| 1413 | kauth_cred_t oc; |
| 1414 | struct proc *p; |
| 1415 | |
| 1416 | p = l->l_proc; |
| 1417 | oc = l->l_cred; |
| 1418 | |
| 1419 | mutex_enter(p->p_lock); |
| 1420 | kauth_cred_hold(p->p_cred); |
| 1421 | l->l_cred = p->p_cred; |
| 1422 | l->l_prflag &= ~LPR_CRMOD; |
| 1423 | mutex_exit(p->p_lock); |
| 1424 | if (oc != NULL) |
| 1425 | kauth_cred_free(oc); |
| 1426 | } |
| 1427 | |
| 1428 | /* |
| 1429 | * Verify that an LWP is locked, and optionally verify that the lock matches |
| 1430 | * one we specify. |
| 1431 | */ |
| 1432 | int |
| 1433 | lwp_locked(struct lwp *l, kmutex_t *mtx) |
| 1434 | { |
| 1435 | kmutex_t *cur = l->l_mutex; |
| 1436 | |
| 1437 | return mutex_owned(cur) && (mtx == cur || mtx == NULL); |
| 1438 | } |
| 1439 | |
| 1440 | /* |
| 1441 | * Lend a new mutex to an LWP. The old mutex must be held. |
| 1442 | */ |
| 1443 | void |
| 1444 | lwp_setlock(struct lwp *l, kmutex_t *mtx) |
| 1445 | { |
| 1446 | |
| 1447 | KASSERT(mutex_owned(l->l_mutex)); |
| 1448 | |
| 1449 | membar_exit(); |
| 1450 | l->l_mutex = mtx; |
| 1451 | } |
| 1452 | |
| 1453 | /* |
| 1454 | * Lend a new mutex to an LWP, and release the old mutex. The old mutex |
| 1455 | * must be held. |
| 1456 | */ |
| 1457 | void |
| 1458 | lwp_unlock_to(struct lwp *l, kmutex_t *mtx) |
| 1459 | { |
| 1460 | kmutex_t *old; |
| 1461 | |
| 1462 | KASSERT(lwp_locked(l, NULL)); |
| 1463 | |
| 1464 | old = l->l_mutex; |
| 1465 | membar_exit(); |
| 1466 | l->l_mutex = mtx; |
| 1467 | mutex_spin_exit(old); |
| 1468 | } |
| 1469 | |
| 1470 | int |
| 1471 | lwp_trylock(struct lwp *l) |
| 1472 | { |
| 1473 | kmutex_t *old; |
| 1474 | |
| 1475 | for (;;) { |
| 1476 | if (!mutex_tryenter(old = l->l_mutex)) |
| 1477 | return 0; |
| 1478 | if (__predict_true(l->l_mutex == old)) |
| 1479 | return 1; |
| 1480 | mutex_spin_exit(old); |
| 1481 | } |
| 1482 | } |
| 1483 | |
| 1484 | void |
| 1485 | lwp_unsleep(lwp_t *l, bool cleanup) |
| 1486 | { |
| 1487 | |
| 1488 | KASSERT(mutex_owned(l->l_mutex)); |
| 1489 | (*l->l_syncobj->sobj_unsleep)(l, cleanup); |
| 1490 | } |
| 1491 | |
| 1492 | /* |
| 1493 | * Handle exceptions for mi_userret(). Called if a member of LW_USERRET is |
| 1494 | * set. |
| 1495 | */ |
| 1496 | void |
| 1497 | lwp_userret(struct lwp *l) |
| 1498 | { |
| 1499 | struct proc *p; |
| 1500 | int sig; |
| 1501 | |
| 1502 | KASSERT(l == curlwp); |
| 1503 | KASSERT(l->l_stat == LSONPROC); |
| 1504 | p = l->l_proc; |
| 1505 | |
| 1506 | #ifndef __HAVE_FAST_SOFTINTS |
| 1507 | /* Run pending soft interrupts. */ |
| 1508 | if (l->l_cpu->ci_data.cpu_softints != 0) |
| 1509 | softint_overlay(); |
| 1510 | #endif |
| 1511 | |
| 1512 | /* |
| 1513 | * It is safe to do this read unlocked on a MP system.. |
| 1514 | */ |
| 1515 | while ((l->l_flag & LW_USERRET) != 0) { |
| 1516 | /* |
| 1517 | * Process pending signals first, unless the process |
| 1518 | * is dumping core or exiting, where we will instead |
| 1519 | * enter the LW_WSUSPEND case below. |
| 1520 | */ |
| 1521 | if ((l->l_flag & (LW_PENDSIG | LW_WCORE | LW_WEXIT)) == |
| 1522 | LW_PENDSIG) { |
| 1523 | mutex_enter(p->p_lock); |
| 1524 | while ((sig = issignal(l)) != 0) |
| 1525 | postsig(sig); |
| 1526 | mutex_exit(p->p_lock); |
| 1527 | } |
| 1528 | |
| 1529 | /* |
| 1530 | * Core-dump or suspend pending. |
| 1531 | * |
| 1532 | * In case of core dump, suspend ourselves, so that the kernel |
| 1533 | * stack and therefore the userland registers saved in the |
| 1534 | * trapframe are around for coredump() to write them out. |
| 1535 | * We also need to save any PCU resources that we have so that |
| 1536 | * they accessible for coredump(). We issue a wakeup on |
| 1537 | * p->p_lwpcv so that sigexit() will write the core file out |
| 1538 | * once all other LWPs are suspended. |
| 1539 | */ |
| 1540 | if ((l->l_flag & LW_WSUSPEND) != 0) { |
| 1541 | pcu_save_all(l); |
| 1542 | mutex_enter(p->p_lock); |
| 1543 | p->p_nrlwps--; |
| 1544 | cv_broadcast(&p->p_lwpcv); |
| 1545 | lwp_lock(l); |
| 1546 | l->l_stat = LSSUSPENDED; |
| 1547 | lwp_unlock(l); |
| 1548 | mutex_exit(p->p_lock); |
| 1549 | lwp_lock(l); |
| 1550 | mi_switch(l); |
| 1551 | } |
| 1552 | |
| 1553 | /* Process is exiting. */ |
| 1554 | if ((l->l_flag & LW_WEXIT) != 0) { |
| 1555 | lwp_exit(l); |
| 1556 | KASSERT(0); |
| 1557 | /* NOTREACHED */ |
| 1558 | } |
| 1559 | |
| 1560 | /* update lwpctl processor (for vfork child_return) */ |
| 1561 | if (l->l_flag & LW_LWPCTL) { |
| 1562 | lwp_lock(l); |
| 1563 | KASSERT(kpreempt_disabled()); |
| 1564 | l->l_lwpctl->lc_curcpu = (int)cpu_index(l->l_cpu); |
| 1565 | l->l_lwpctl->lc_pctr++; |
| 1566 | l->l_flag &= ~LW_LWPCTL; |
| 1567 | lwp_unlock(l); |
| 1568 | } |
| 1569 | } |
| 1570 | } |
| 1571 | |
| 1572 | /* |
| 1573 | * Force an LWP to enter the kernel, to take a trip through lwp_userret(). |
| 1574 | */ |
| 1575 | void |
| 1576 | lwp_need_userret(struct lwp *l) |
| 1577 | { |
| 1578 | KASSERT(lwp_locked(l, NULL)); |
| 1579 | |
| 1580 | /* |
| 1581 | * Since the tests in lwp_userret() are done unlocked, make sure |
| 1582 | * that the condition will be seen before forcing the LWP to enter |
| 1583 | * kernel mode. |
| 1584 | */ |
| 1585 | membar_producer(); |
| 1586 | cpu_signotify(l); |
| 1587 | } |
| 1588 | |
| 1589 | /* |
| 1590 | * Add one reference to an LWP. This will prevent the LWP from |
| 1591 | * exiting, thus keep the lwp structure and PCB around to inspect. |
| 1592 | */ |
| 1593 | void |
| 1594 | lwp_addref(struct lwp *l) |
| 1595 | { |
| 1596 | |
| 1597 | KASSERT(mutex_owned(l->l_proc->p_lock)); |
| 1598 | KASSERT(l->l_stat != LSZOMB); |
| 1599 | KASSERT(l->l_refcnt != 0); |
| 1600 | |
| 1601 | l->l_refcnt++; |
| 1602 | } |
| 1603 | |
| 1604 | /* |
| 1605 | * Remove one reference to an LWP. If this is the last reference, |
| 1606 | * then we must finalize the LWP's death. |
| 1607 | */ |
| 1608 | void |
| 1609 | lwp_delref(struct lwp *l) |
| 1610 | { |
| 1611 | struct proc *p = l->l_proc; |
| 1612 | |
| 1613 | mutex_enter(p->p_lock); |
| 1614 | lwp_delref2(l); |
| 1615 | mutex_exit(p->p_lock); |
| 1616 | } |
| 1617 | |
| 1618 | /* |
| 1619 | * Remove one reference to an LWP. If this is the last reference, |
| 1620 | * then we must finalize the LWP's death. The proc mutex is held |
| 1621 | * on entry. |
| 1622 | */ |
| 1623 | void |
| 1624 | lwp_delref2(struct lwp *l) |
| 1625 | { |
| 1626 | struct proc *p = l->l_proc; |
| 1627 | |
| 1628 | KASSERT(mutex_owned(p->p_lock)); |
| 1629 | KASSERT(l->l_stat != LSZOMB); |
| 1630 | KASSERT(l->l_refcnt > 0); |
| 1631 | if (--l->l_refcnt == 0) |
| 1632 | cv_broadcast(&p->p_lwpcv); |
| 1633 | } |
| 1634 | |
| 1635 | /* |
| 1636 | * Drain all references to the current LWP. |
| 1637 | */ |
| 1638 | void |
| 1639 | lwp_drainrefs(struct lwp *l) |
| 1640 | { |
| 1641 | struct proc *p = l->l_proc; |
| 1642 | |
| 1643 | KASSERT(mutex_owned(p->p_lock)); |
| 1644 | KASSERT(l->l_refcnt != 0); |
| 1645 | |
| 1646 | l->l_refcnt--; |
| 1647 | while (l->l_refcnt != 0) |
| 1648 | cv_wait(&p->p_lwpcv, p->p_lock); |
| 1649 | } |
| 1650 | |
| 1651 | /* |
| 1652 | * Return true if the specified LWP is 'alive'. Only p->p_lock need |
| 1653 | * be held. |
| 1654 | */ |
| 1655 | bool |
| 1656 | lwp_alive(lwp_t *l) |
| 1657 | { |
| 1658 | |
| 1659 | KASSERT(mutex_owned(l->l_proc->p_lock)); |
| 1660 | |
| 1661 | switch (l->l_stat) { |
| 1662 | case LSSLEEP: |
| 1663 | case LSRUN: |
| 1664 | case LSONPROC: |
| 1665 | case LSSTOP: |
| 1666 | case LSSUSPENDED: |
| 1667 | return true; |
| 1668 | default: |
| 1669 | return false; |
| 1670 | } |
| 1671 | } |
| 1672 | |
| 1673 | /* |
| 1674 | * Return first live LWP in the process. |
| 1675 | */ |
| 1676 | lwp_t * |
| 1677 | lwp_find_first(proc_t *p) |
| 1678 | { |
| 1679 | lwp_t *l; |
| 1680 | |
| 1681 | KASSERT(mutex_owned(p->p_lock)); |
| 1682 | |
| 1683 | LIST_FOREACH(l, &p->p_lwps, l_sibling) { |
| 1684 | if (lwp_alive(l)) { |
| 1685 | return l; |
| 1686 | } |
| 1687 | } |
| 1688 | |
| 1689 | return NULL; |
| 1690 | } |
| 1691 | |
| 1692 | /* |
| 1693 | * Allocate a new lwpctl structure for a user LWP. |
| 1694 | */ |
| 1695 | int |
| 1696 | lwp_ctl_alloc(vaddr_t *uaddr) |
| 1697 | { |
| 1698 | lcproc_t *lp; |
| 1699 | u_int bit, i, offset; |
| 1700 | struct uvm_object *uao; |
| 1701 | int error; |
| 1702 | lcpage_t *lcp; |
| 1703 | proc_t *p; |
| 1704 | lwp_t *l; |
| 1705 | |
| 1706 | l = curlwp; |
| 1707 | p = l->l_proc; |
| 1708 | |
| 1709 | /* don't allow a vforked process to create lwp ctls */ |
| 1710 | if (p->p_lflag & PL_PPWAIT) |
| 1711 | return EBUSY; |
| 1712 | |
| 1713 | if (l->l_lcpage != NULL) { |
| 1714 | lcp = l->l_lcpage; |
| 1715 | *uaddr = lcp->lcp_uaddr + (vaddr_t)l->l_lwpctl - lcp->lcp_kaddr; |
| 1716 | return 0; |
| 1717 | } |
| 1718 | |
| 1719 | /* First time around, allocate header structure for the process. */ |
| 1720 | if ((lp = p->p_lwpctl) == NULL) { |
| 1721 | lp = kmem_alloc(sizeof(*lp), KM_SLEEP); |
| 1722 | mutex_init(&lp->lp_lock, MUTEX_DEFAULT, IPL_NONE); |
| 1723 | lp->lp_uao = NULL; |
| 1724 | TAILQ_INIT(&lp->lp_pages); |
| 1725 | mutex_enter(p->p_lock); |
| 1726 | if (p->p_lwpctl == NULL) { |
| 1727 | p->p_lwpctl = lp; |
| 1728 | mutex_exit(p->p_lock); |
| 1729 | } else { |
| 1730 | mutex_exit(p->p_lock); |
| 1731 | mutex_destroy(&lp->lp_lock); |
| 1732 | kmem_free(lp, sizeof(*lp)); |
| 1733 | lp = p->p_lwpctl; |
| 1734 | } |
| 1735 | } |
| 1736 | |
| 1737 | /* |
| 1738 | * Set up an anonymous memory region to hold the shared pages. |
| 1739 | * Map them into the process' address space. The user vmspace |
| 1740 | * gets the first reference on the UAO. |
| 1741 | */ |
| 1742 | mutex_enter(&lp->lp_lock); |
| 1743 | if (lp->lp_uao == NULL) { |
| 1744 | lp->lp_uao = uao_create(LWPCTL_UAREA_SZ, 0); |
| 1745 | lp->lp_cur = 0; |
| 1746 | lp->lp_max = LWPCTL_UAREA_SZ; |
| 1747 | lp->lp_uva = p->p_emul->e_vm_default_addr(p, |
| 1748 | (vaddr_t)p->p_vmspace->vm_daddr, LWPCTL_UAREA_SZ, |
| 1749 | p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN); |
| 1750 | error = uvm_map(&p->p_vmspace->vm_map, &lp->lp_uva, |
| 1751 | LWPCTL_UAREA_SZ, lp->lp_uao, 0, 0, UVM_MAPFLAG(UVM_PROT_RW, |
| 1752 | UVM_PROT_RW, UVM_INH_NONE, UVM_ADV_NORMAL, 0)); |
| 1753 | if (error != 0) { |
| 1754 | uao_detach(lp->lp_uao); |
| 1755 | lp->lp_uao = NULL; |
| 1756 | mutex_exit(&lp->lp_lock); |
| 1757 | return error; |
| 1758 | } |
| 1759 | } |
| 1760 | |
| 1761 | /* Get a free block and allocate for this LWP. */ |
| 1762 | TAILQ_FOREACH(lcp, &lp->lp_pages, lcp_chain) { |
| 1763 | if (lcp->lcp_nfree != 0) |
| 1764 | break; |
| 1765 | } |
| 1766 | if (lcp == NULL) { |
| 1767 | /* Nothing available - try to set up a free page. */ |
| 1768 | if (lp->lp_cur == lp->lp_max) { |
| 1769 | mutex_exit(&lp->lp_lock); |
| 1770 | return ENOMEM; |
| 1771 | } |
| 1772 | lcp = kmem_alloc(LWPCTL_LCPAGE_SZ, KM_SLEEP); |
| 1773 | if (lcp == NULL) { |
| 1774 | mutex_exit(&lp->lp_lock); |
| 1775 | return ENOMEM; |
| 1776 | } |
| 1777 | /* |
| 1778 | * Wire the next page down in kernel space. Since this |
| 1779 | * is a new mapping, we must add a reference. |
| 1780 | */ |
| 1781 | uao = lp->lp_uao; |
| 1782 | (*uao->pgops->pgo_reference)(uao); |
| 1783 | lcp->lcp_kaddr = vm_map_min(kernel_map); |
| 1784 | error = uvm_map(kernel_map, &lcp->lcp_kaddr, PAGE_SIZE, |
| 1785 | uao, lp->lp_cur, PAGE_SIZE, |
| 1786 | UVM_MAPFLAG(UVM_PROT_RW, UVM_PROT_RW, |
| 1787 | UVM_INH_NONE, UVM_ADV_RANDOM, 0)); |
| 1788 | if (error != 0) { |
| 1789 | mutex_exit(&lp->lp_lock); |
| 1790 | kmem_free(lcp, LWPCTL_LCPAGE_SZ); |
| 1791 | (*uao->pgops->pgo_detach)(uao); |
| 1792 | return error; |
| 1793 | } |
| 1794 | error = uvm_map_pageable(kernel_map, lcp->lcp_kaddr, |
| 1795 | lcp->lcp_kaddr + PAGE_SIZE, FALSE, 0); |
| 1796 | if (error != 0) { |
| 1797 | mutex_exit(&lp->lp_lock); |
| 1798 | uvm_unmap(kernel_map, lcp->lcp_kaddr, |
| 1799 | lcp->lcp_kaddr + PAGE_SIZE); |
| 1800 | kmem_free(lcp, LWPCTL_LCPAGE_SZ); |
| 1801 | return error; |
| 1802 | } |
| 1803 | /* Prepare the page descriptor and link into the list. */ |
| 1804 | lcp->lcp_uaddr = lp->lp_uva + lp->lp_cur; |
| 1805 | lp->lp_cur += PAGE_SIZE; |
| 1806 | lcp->lcp_nfree = LWPCTL_PER_PAGE; |
| 1807 | lcp->lcp_rotor = 0; |
| 1808 | memset(lcp->lcp_bitmap, 0xff, LWPCTL_BITMAP_SZ); |
| 1809 | TAILQ_INSERT_HEAD(&lp->lp_pages, lcp, lcp_chain); |
| 1810 | } |
| 1811 | for (i = lcp->lcp_rotor; lcp->lcp_bitmap[i] == 0;) { |
| 1812 | if (++i >= LWPCTL_BITMAP_ENTRIES) |
| 1813 | i = 0; |
| 1814 | } |
| 1815 | bit = ffs(lcp->lcp_bitmap[i]) - 1; |
| 1816 | lcp->lcp_bitmap[i] ^= (1 << bit); |
| 1817 | lcp->lcp_rotor = i; |
| 1818 | lcp->lcp_nfree--; |
| 1819 | l->l_lcpage = lcp; |
| 1820 | offset = (i << 5) + bit; |
| 1821 | l->l_lwpctl = (lwpctl_t *)lcp->lcp_kaddr + offset; |
| 1822 | *uaddr = lcp->lcp_uaddr + offset * sizeof(lwpctl_t); |
| 1823 | mutex_exit(&lp->lp_lock); |
| 1824 | |
| 1825 | KPREEMPT_DISABLE(l); |
| 1826 | l->l_lwpctl->lc_curcpu = (int)curcpu()->ci_data.cpu_index; |
| 1827 | KPREEMPT_ENABLE(l); |
| 1828 | |
| 1829 | return 0; |
| 1830 | } |
| 1831 | |
| 1832 | /* |
| 1833 | * Free an lwpctl structure back to the per-process list. |
| 1834 | */ |
| 1835 | void |
| 1836 | lwp_ctl_free(lwp_t *l) |
| 1837 | { |
| 1838 | struct proc *p = l->l_proc; |
| 1839 | lcproc_t *lp; |
| 1840 | lcpage_t *lcp; |
| 1841 | u_int map, offset; |
| 1842 | |
| 1843 | /* don't free a lwp context we borrowed for vfork */ |
| 1844 | if (p->p_lflag & PL_PPWAIT) { |
| 1845 | l->l_lwpctl = NULL; |
| 1846 | return; |
| 1847 | } |
| 1848 | |
| 1849 | lp = p->p_lwpctl; |
| 1850 | KASSERT(lp != NULL); |
| 1851 | |
| 1852 | lcp = l->l_lcpage; |
| 1853 | offset = (u_int)((lwpctl_t *)l->l_lwpctl - (lwpctl_t *)lcp->lcp_kaddr); |
| 1854 | KASSERT(offset < LWPCTL_PER_PAGE); |
| 1855 | |
| 1856 | mutex_enter(&lp->lp_lock); |
| 1857 | lcp->lcp_nfree++; |
| 1858 | map = offset >> 5; |
| 1859 | lcp->lcp_bitmap[map] |= (1 << (offset & 31)); |
| 1860 | if (lcp->lcp_bitmap[lcp->lcp_rotor] == 0) |
| 1861 | lcp->lcp_rotor = map; |
| 1862 | if (TAILQ_FIRST(&lp->lp_pages)->lcp_nfree == 0) { |
| 1863 | TAILQ_REMOVE(&lp->lp_pages, lcp, lcp_chain); |
| 1864 | TAILQ_INSERT_HEAD(&lp->lp_pages, lcp, lcp_chain); |
| 1865 | } |
| 1866 | mutex_exit(&lp->lp_lock); |
| 1867 | } |
| 1868 | |
| 1869 | /* |
| 1870 | * Process is exiting; tear down lwpctl state. This can only be safely |
| 1871 | * called by the last LWP in the process. |
| 1872 | */ |
| 1873 | void |
| 1874 | lwp_ctl_exit(void) |
| 1875 | { |
| 1876 | lcpage_t *lcp, *next; |
| 1877 | lcproc_t *lp; |
| 1878 | proc_t *p; |
| 1879 | lwp_t *l; |
| 1880 | |
| 1881 | l = curlwp; |
| 1882 | l->l_lwpctl = NULL; |
| 1883 | l->l_lcpage = NULL; |
| 1884 | p = l->l_proc; |
| 1885 | lp = p->p_lwpctl; |
| 1886 | |
| 1887 | KASSERT(lp != NULL); |
| 1888 | KASSERT(p->p_nlwps == 1); |
| 1889 | |
| 1890 | for (lcp = TAILQ_FIRST(&lp->lp_pages); lcp != NULL; lcp = next) { |
| 1891 | next = TAILQ_NEXT(lcp, lcp_chain); |
| 1892 | uvm_unmap(kernel_map, lcp->lcp_kaddr, |
| 1893 | lcp->lcp_kaddr + PAGE_SIZE); |
| 1894 | kmem_free(lcp, LWPCTL_LCPAGE_SZ); |
| 1895 | } |
| 1896 | |
| 1897 | if (lp->lp_uao != NULL) { |
| 1898 | uvm_unmap(&p->p_vmspace->vm_map, lp->lp_uva, |
| 1899 | lp->lp_uva + LWPCTL_UAREA_SZ); |
| 1900 | } |
| 1901 | |
| 1902 | mutex_destroy(&lp->lp_lock); |
| 1903 | kmem_free(lp, sizeof(*lp)); |
| 1904 | p->p_lwpctl = NULL; |
| 1905 | } |
| 1906 | |
| 1907 | /* |
| 1908 | * Return the current LWP's "preemption counter". Used to detect |
| 1909 | * preemption across operations that can tolerate preemption without |
| 1910 | * crashing, but which may generate incorrect results if preempted. |
| 1911 | */ |
| 1912 | uint64_t |
| 1913 | lwp_pctr(void) |
| 1914 | { |
| 1915 | |
| 1916 | return curlwp->l_ncsw; |
| 1917 | } |
| 1918 | |
| 1919 | /* |
| 1920 | * Set an LWP's private data pointer. |
| 1921 | */ |
| 1922 | int |
| 1923 | lwp_setprivate(struct lwp *l, void *ptr) |
| 1924 | { |
| 1925 | int error = 0; |
| 1926 | |
| 1927 | l->l_private = ptr; |
| 1928 | #ifdef __HAVE_CPU_LWP_SETPRIVATE |
| 1929 | error = cpu_lwp_setprivate(l, ptr); |
| 1930 | #endif |
| 1931 | return error; |
| 1932 | } |
| 1933 | |
| 1934 | #if defined(DDB) |
| 1935 | #include <machine/pcb.h> |
| 1936 | |
| 1937 | void |
| 1938 | lwp_whatis(uintptr_t addr, void (*pr)(const char *, ...)) |
| 1939 | { |
| 1940 | lwp_t *l; |
| 1941 | |
| 1942 | LIST_FOREACH(l, &alllwp, l_list) { |
| 1943 | uintptr_t stack = (uintptr_t)KSTACK_LOWEST_ADDR(l); |
| 1944 | |
| 1945 | if (addr < stack || stack + KSTACK_SIZE <= addr) { |
| 1946 | continue; |
| 1947 | } |
| 1948 | (*pr)("%p is %p+%zu, LWP %p's stack\n" , |
| 1949 | (void *)addr, (void *)stack, |
| 1950 | (size_t)(addr - stack), l); |
| 1951 | } |
| 1952 | } |
| 1953 | #endif /* defined(DDB) */ |
| 1954 | |