Add missing va_end(ap);
[dragonfly.git] / sys / kern / lwkt_thread.c
CommitLineData
8ad65e08 1/*
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2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
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7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
8c10bfcf 10 *
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11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
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14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
8ad65e08 32 * SUCH DAMAGE.
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33 *
34 * $DragonFly: src/sys/kern/lwkt_thread.c,v 1.65 2004/07/16 05:51:10 dillon Exp $
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35 */
36
37/*
38 * Each cpu in a system has its own self-contained light weight kernel
39 * thread scheduler, which means that generally speaking we only need
40 * to use a critical section to avoid problems. Foreign thread
41 * scheduling is queued via (async) IPIs.
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42 */
43
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44#ifdef _KERNEL
45
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46#include <sys/param.h>
47#include <sys/systm.h>
48#include <sys/kernel.h>
49#include <sys/proc.h>
50#include <sys/rtprio.h>
51#include <sys/queue.h>
f1d1c3fa 52#include <sys/thread2.h>
7d0bac62 53#include <sys/sysctl.h>
99df837e 54#include <sys/kthread.h>
f1d1c3fa 55#include <machine/cpu.h>
99df837e 56#include <sys/lock.h>
f6bf3af1 57#include <sys/caps.h>
f1d1c3fa 58
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59#include <vm/vm.h>
60#include <vm/vm_param.h>
61#include <vm/vm_kern.h>
62#include <vm/vm_object.h>
63#include <vm/vm_page.h>
64#include <vm/vm_map.h>
65#include <vm/vm_pager.h>
66#include <vm/vm_extern.h>
67#include <vm/vm_zone.h>
68
99df837e 69#include <machine/stdarg.h>
57c254db 70#include <machine/ipl.h>
96728c05 71#include <machine/smp.h>
99df837e 72
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73#define THREAD_STACK (UPAGES * PAGE_SIZE)
74
75#else
76
77#include <sys/stdint.h>
fb04f4fd 78#include <libcaps/thread.h>
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79#include <sys/thread.h>
80#include <sys/msgport.h>
81#include <sys/errno.h>
fb04f4fd 82#include <libcaps/globaldata.h>
7e8303ad 83#include <machine/cpufunc.h>
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84#include <sys/thread2.h>
85#include <sys/msgport2.h>
709799ea 86#include <stdio.h>
05220613 87#include <stdlib.h>
709799ea 88#include <string.h>
709799ea 89#include <machine/lock.h>
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90
91#endif
92
7d0bac62 93static int untimely_switch = 0;
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94#ifdef INVARIANTS
95static int panic_on_cscount = 0;
96#endif
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97static __int64_t switch_count = 0;
98static __int64_t preempt_hit = 0;
99static __int64_t preempt_miss = 0;
100static __int64_t preempt_weird = 0;
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101
102#ifdef _KERNEL
103
104SYSCTL_INT(_lwkt, OID_AUTO, untimely_switch, CTLFLAG_RW, &untimely_switch, 0, "");
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105#ifdef INVARIANTS
106SYSCTL_INT(_lwkt, OID_AUTO, panic_on_cscount, CTLFLAG_RW, &panic_on_cscount, 0, "");
107#endif
4b5f931b 108SYSCTL_QUAD(_lwkt, OID_AUTO, switch_count, CTLFLAG_RW, &switch_count, 0, "");
4b5f931b 109SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_hit, CTLFLAG_RW, &preempt_hit, 0, "");
4b5f931b 110SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_miss, CTLFLAG_RW, &preempt_miss, 0, "");
26a0694b 111SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_weird, CTLFLAG_RW, &preempt_weird, 0, "");
7d0bac62 112
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113#endif
114
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115/*
116 * These helper procedures handle the runq, they can only be called from
117 * within a critical section.
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118 *
119 * WARNING! Prior to SMP being brought up it is possible to enqueue and
120 * dequeue threads belonging to other cpus, so be sure to use td->td_gd
121 * instead of 'mycpu' when referencing the globaldata structure. Once
122 * SMP live enqueuing and dequeueing only occurs on the current cpu.
4b5f931b 123 */
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124static __inline
125void
126_lwkt_dequeue(thread_t td)
127{
128 if (td->td_flags & TDF_RUNQ) {
4b5f931b 129 int nq = td->td_pri & TDPRI_MASK;
75cdbe6c 130 struct globaldata *gd = td->td_gd;
4b5f931b 131
f1d1c3fa 132 td->td_flags &= ~TDF_RUNQ;
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133 TAILQ_REMOVE(&gd->gd_tdrunq[nq], td, td_threadq);
134 /* runqmask is passively cleaned up by the switcher */
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135 }
136}
137
138static __inline
139void
140_lwkt_enqueue(thread_t td)
141{
5d21b981 142 if ((td->td_flags & (TDF_RUNQ|TDF_MIGRATING)) == 0) {
4b5f931b 143 int nq = td->td_pri & TDPRI_MASK;
75cdbe6c 144 struct globaldata *gd = td->td_gd;
4b5f931b 145
f1d1c3fa 146 td->td_flags |= TDF_RUNQ;
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147 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], td, td_threadq);
148 gd->gd_runqmask |= 1 << nq;
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149 }
150}
8ad65e08 151
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152/*
153 * Schedule a thread to run. As the current thread we can always safely
154 * schedule ourselves, and a shortcut procedure is provided for that
155 * function.
156 *
157 * (non-blocking, self contained on a per cpu basis)
158 */
159void
160lwkt_schedule_self(thread_t td)
161{
162 crit_enter_quick(td);
163 KASSERT(td->td_wait == NULL, ("lwkt_schedule_self(): td_wait not NULL!"));
164 KASSERT(td != &td->td_gd->gd_idlethread, ("lwkt_schedule_self(): scheduling gd_idlethread is illegal!"));
165 _lwkt_enqueue(td);
166#ifdef _KERNEL
167 if (td->td_proc && td->td_proc->p_stat == SSLEEP)
168 panic("SCHED SELF PANIC");
169#endif
170 crit_exit_quick(td);
171}
172
173/*
174 * Deschedule a thread.
175 *
176 * (non-blocking, self contained on a per cpu basis)
177 */
178void
179lwkt_deschedule_self(thread_t td)
180{
181 crit_enter_quick(td);
182 KASSERT(td->td_wait == NULL, ("lwkt_schedule_self(): td_wait not NULL!"));
183 _lwkt_dequeue(td);
184 crit_exit_quick(td);
185}
186
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187#ifdef _KERNEL
188
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189/*
190 * LWKTs operate on a per-cpu basis
191 *
73e4f7b9 192 * WARNING! Called from early boot, 'mycpu' may not work yet.
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193 */
194void
195lwkt_gdinit(struct globaldata *gd)
196{
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197 int i;
198
199 for (i = 0; i < sizeof(gd->gd_tdrunq)/sizeof(gd->gd_tdrunq[0]); ++i)
200 TAILQ_INIT(&gd->gd_tdrunq[i]);
201 gd->gd_runqmask = 0;
73e4f7b9 202 TAILQ_INIT(&gd->gd_tdallq);
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203}
204
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205#endif /* _KERNEL */
206
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207/*
208 * Initialize a thread wait structure prior to first use.
209 *
210 * NOTE! called from low level boot code, we cannot do anything fancy!
211 */
212void
41a01a4d 213lwkt_wait_init(lwkt_wait_t w)
7d0bac62 214{
41a01a4d 215 lwkt_token_init(&w->wa_token);
7d0bac62 216 TAILQ_INIT(&w->wa_waitq);
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217 w->wa_gen = 0;
218 w->wa_count = 0;
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219}
220
221/*
222 * Create a new thread. The thread must be associated with a process context
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223 * or LWKT start address before it can be scheduled. If the target cpu is
224 * -1 the thread will be created on the current cpu.
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225 *
226 * If you intend to create a thread without a process context this function
227 * does everything except load the startup and switcher function.
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228 */
229thread_t
75cdbe6c 230lwkt_alloc_thread(struct thread *td, int cpu)
7d0bac62 231{
99df837e 232 void *stack;
ef0fdad1 233 int flags = 0;
37af14fe 234 globaldata_t gd = mycpu;
7d0bac62 235
ef0fdad1 236 if (td == NULL) {
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237 crit_enter_gd(gd);
238 if (gd->gd_tdfreecount > 0) {
239 --gd->gd_tdfreecount;
240 td = TAILQ_FIRST(&gd->gd_tdfreeq);
d9eea1a5 241 KASSERT(td != NULL && (td->td_flags & TDF_RUNNING) == 0,
ef0fdad1 242 ("lwkt_alloc_thread: unexpected NULL or corrupted td"));
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243 TAILQ_REMOVE(&gd->gd_tdfreeq, td, td_threadq);
244 crit_exit_gd(gd);
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245 stack = td->td_kstack;
246 flags = td->td_flags & (TDF_ALLOCATED_STACK|TDF_ALLOCATED_THREAD);
247 } else {
37af14fe 248 crit_exit_gd(gd);
05220613 249#ifdef _KERNEL
ef0fdad1 250 td = zalloc(thread_zone);
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251#else
252 td = malloc(sizeof(struct thread));
253#endif
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254 td->td_kstack = NULL;
255 flags |= TDF_ALLOCATED_THREAD;
256 }
257 }
258 if ((stack = td->td_kstack) == NULL) {
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259#ifdef _KERNEL
260 stack = (void *)kmem_alloc(kernel_map, THREAD_STACK);
261#else
fb04f4fd 262 stack = libcaps_alloc_stack(THREAD_STACK);
05220613 263#endif
ef0fdad1 264 flags |= TDF_ALLOCATED_STACK;
99df837e 265 }
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266 if (cpu < 0)
267 lwkt_init_thread(td, stack, flags, mycpu);
268 else
269 lwkt_init_thread(td, stack, flags, globaldata_find(cpu));
99df837e 270 return(td);
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271}
272
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273#ifdef _KERNEL
274
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275/*
276 * Initialize a preexisting thread structure. This function is used by
277 * lwkt_alloc_thread() and also used to initialize the per-cpu idlethread.
278 *
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279 * All threads start out in a critical section at a priority of
280 * TDPRI_KERN_DAEMON. Higher level code will modify the priority as
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281 * appropriate. This function may send an IPI message when the
282 * requested cpu is not the current cpu and consequently gd_tdallq may
283 * not be initialized synchronously from the point of view of the originating
284 * cpu.
285 *
286 * NOTE! we have to be careful in regards to creating threads for other cpus
287 * if SMP has not yet been activated.
7d0bac62 288 */
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289#ifdef SMP
290
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291static void
292lwkt_init_thread_remote(void *arg)
293{
294 thread_t td = arg;
295
296 TAILQ_INSERT_TAIL(&td->td_gd->gd_tdallq, td, td_allq);
297}
298
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299#endif
300
7d0bac62 301void
26a0694b 302lwkt_init_thread(thread_t td, void *stack, int flags, struct globaldata *gd)
7d0bac62 303{
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304 globaldata_t mygd = mycpu;
305
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306 bzero(td, sizeof(struct thread));
307 td->td_kstack = stack;
308 td->td_flags |= flags;
26a0694b 309 td->td_gd = gd;
f8c3996b 310 td->td_pri = TDPRI_KERN_DAEMON + TDPRI_CRIT;
c95cd171 311 lwkt_initport(&td->td_msgport, td);
99df837e 312 pmap_init_thread(td);
0f7a3396 313#ifdef SMP
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314 /*
315 * Normally initializing a thread for a remote cpu requires sending an
316 * IPI. However, the idlethread is setup before the other cpus are
317 * activated so we have to treat it as a special case. XXX manipulation
318 * of gd_tdallq requires the BGL.
319 */
320 if (gd == mygd || td == &gd->gd_idlethread) {
37af14fe 321 crit_enter_gd(mygd);
75cdbe6c 322 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
37af14fe 323 crit_exit_gd(mygd);
75cdbe6c 324 } else {
2db3b277 325 lwkt_send_ipiq(gd, lwkt_init_thread_remote, td);
75cdbe6c 326 }
0f7a3396 327#else
37af14fe 328 crit_enter_gd(mygd);
0f7a3396 329 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
37af14fe 330 crit_exit_gd(mygd);
0f7a3396 331#endif
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332}
333
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334#endif /* _KERNEL */
335
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336void
337lwkt_set_comm(thread_t td, const char *ctl, ...)
338{
e2565a42 339 __va_list va;
73e4f7b9 340
e2565a42 341 __va_start(va, ctl);
73e4f7b9 342 vsnprintf(td->td_comm, sizeof(td->td_comm), ctl, va);
e2565a42 343 __va_end(va);
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344}
345
99df837e 346void
73e4f7b9 347lwkt_hold(thread_t td)
99df837e 348{
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349 ++td->td_refs;
350}
351
352void
353lwkt_rele(thread_t td)
354{
355 KKASSERT(td->td_refs > 0);
356 --td->td_refs;
357}
358
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359#ifdef _KERNEL
360
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361void
362lwkt_wait_free(thread_t td)
363{
364 while (td->td_refs)
377d4740 365 tsleep(td, 0, "tdreap", hz);
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366}
367
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368#endif
369
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370void
371lwkt_free_thread(thread_t td)
372{
373 struct globaldata *gd = mycpu;
374
d9eea1a5 375 KASSERT((td->td_flags & TDF_RUNNING) == 0,
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376 ("lwkt_free_thread: did not exit! %p", td));
377
37af14fe 378 crit_enter_gd(gd);
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379 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq);
380 if (gd->gd_tdfreecount < CACHE_NTHREADS &&
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381 (td->td_flags & TDF_ALLOCATED_THREAD)
382 ) {
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383 ++gd->gd_tdfreecount;
384 TAILQ_INSERT_HEAD(&gd->gd_tdfreeq, td, td_threadq);
37af14fe 385 crit_exit_gd(gd);
99df837e 386 } else {
37af14fe 387 crit_exit_gd(gd);
99df837e 388 if (td->td_kstack && (td->td_flags & TDF_ALLOCATED_STACK)) {
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389#ifdef _KERNEL
390 kmem_free(kernel_map, (vm_offset_t)td->td_kstack, THREAD_STACK);
391#else
fb04f4fd 392 libcaps_free_stack(td->td_kstack, THREAD_STACK);
05220613 393#endif
73e4f7b9 394 /* gd invalid */
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395 td->td_kstack = NULL;
396 }
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397 if (td->td_flags & TDF_ALLOCATED_THREAD) {
398#ifdef _KERNEL
99df837e 399 zfree(thread_zone, td);
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400#else
401 free(td);
402#endif
403 }
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404 }
405}
406
407
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408/*
409 * Switch to the next runnable lwkt. If no LWKTs are runnable then
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410 * switch to the idlethread. Switching must occur within a critical
411 * section to avoid races with the scheduling queue.
412 *
413 * We always have full control over our cpu's run queue. Other cpus
414 * that wish to manipulate our queue must use the cpu_*msg() calls to
415 * talk to our cpu, so a critical section is all that is needed and
416 * the result is very, very fast thread switching.
417 *
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418 * The LWKT scheduler uses a fixed priority model and round-robins at
419 * each priority level. User process scheduling is a totally
420 * different beast and LWKT priorities should not be confused with
421 * user process priorities.
f1d1c3fa 422 *
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423 * The MP lock may be out of sync with the thread's td_mpcount. lwkt_switch()
424 * cleans it up. Note that the td_switch() function cannot do anything that
425 * requires the MP lock since the MP lock will have already been setup for
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426 * the target thread (not the current thread). It's nice to have a scheduler
427 * that does not need the MP lock to work because it allows us to do some
428 * really cool high-performance MP lock optimizations.
8ad65e08 429 */
96728c05 430
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431void
432lwkt_switch(void)
433{
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434 globaldata_t gd = mycpu;
435 thread_t td = gd->gd_curthread;
8ad65e08 436 thread_t ntd;
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437#ifdef SMP
438 int mpheld;
439#endif
8ad65e08 440
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441 /*
442 * Switching from within a 'fast' (non thread switched) interrupt is
443 * illegal.
444 */
37af14fe 445 if (gd->gd_intr_nesting_level && panicstr == NULL) {
fc92d4aa 446 panic("lwkt_switch: cannot switch from within a fast interrupt, yet");
96728c05 447 }
ef0fdad1 448
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449 /*
450 * Passive release (used to transition from user to kernel mode
451 * when we block or switch rather then when we enter the kernel).
452 * This function is NOT called if we are switching into a preemption
453 * or returning from a preemption. Typically this causes us to lose
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454 * our current process designation (if we have one) and become a true
455 * LWKT thread, and may also hand the current process designation to
456 * another process and schedule thread.
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457 */
458 if (td->td_release)
459 td->td_release(td);
460
37af14fe 461 crit_enter_gd(gd);
4b5f931b 462 ++switch_count;
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463
464#ifdef SMP
465 /*
466 * td_mpcount cannot be used to determine if we currently hold the
467 * MP lock because get_mplock() will increment it prior to attempting
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468 * to get the lock, and switch out if it can't. Our ownership of
469 * the actual lock will remain stable while we are in a critical section
470 * (but, of course, another cpu may own or release the lock so the
471 * actual value of mp_lock is not stable).
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472 */
473 mpheld = MP_LOCK_HELD();
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474#ifdef INVARIANTS
475 if (td->td_cscount) {
476 printf("Diagnostic: attempt to switch while mastering cpusync: %p\n",
477 td);
478 if (panic_on_cscount)
479 panic("switching while mastering cpusync");
480 }
481#endif
8a8d5d85 482#endif
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483 if ((ntd = td->td_preempted) != NULL) {
484 /*
485 * We had preempted another thread on this cpu, resume the preempted
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486 * thread. This occurs transparently, whether the preempted thread
487 * was scheduled or not (it may have been preempted after descheduling
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488 * itself).
489 *
490 * We have to setup the MP lock for the original thread after backing
491 * out the adjustment that was made to curthread when the original
492 * was preempted.
99df837e 493 */
26a0694b 494 KKASSERT(ntd->td_flags & TDF_PREEMPT_LOCK);
8a8d5d85 495#ifdef SMP
96728c05 496 if (ntd->td_mpcount && mpheld == 0) {
fc92d4aa 497 panic("MPLOCK NOT HELD ON RETURN: %p %p %d %d",
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498 td, ntd, td->td_mpcount, ntd->td_mpcount);
499 }
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500 if (ntd->td_mpcount) {
501 td->td_mpcount -= ntd->td_mpcount;
502 KKASSERT(td->td_mpcount >= 0);
503 }
504#endif
26a0694b 505 ntd->td_flags |= TDF_PREEMPT_DONE;
8a8d5d85 506 /* YYY release mp lock on switchback if original doesn't need it */
8ad65e08 507 } else {
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508 /*
509 * Priority queue / round-robin at each priority. Note that user
510 * processes run at a fixed, low priority and the user process
511 * scheduler deals with interactions between user processes
512 * by scheduling and descheduling them from the LWKT queue as
513 * necessary.
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514 *
515 * We have to adjust the MP lock for the target thread. If we
516 * need the MP lock and cannot obtain it we try to locate a
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517 * thread that does not need the MP lock. If we cannot, we spin
518 * instead of HLT.
519 *
520 * A similar issue exists for the tokens held by the target thread.
521 * If we cannot obtain ownership of the tokens we cannot immediately
522 * schedule the thread.
523 */
524
525 /*
526 * We are switching threads. If there are any pending requests for
527 * tokens we can satisfy all of them here.
4b5f931b 528 */
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529#ifdef SMP
530 if (gd->gd_tokreqbase)
531 lwkt_drain_token_requests();
532#endif
533
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534again:
535 if (gd->gd_runqmask) {
536 int nq = bsrl(gd->gd_runqmask);
537 if ((ntd = TAILQ_FIRST(&gd->gd_tdrunq[nq])) == NULL) {
538 gd->gd_runqmask &= ~(1 << nq);
539 goto again;
540 }
8a8d5d85 541#ifdef SMP
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542 /*
543 * If the target needs the MP lock and we couldn't get it,
544 * or if the target is holding tokens and we could not
545 * gain ownership of the tokens, continue looking for a
546 * thread to schedule and spin instead of HLT if we can't.
547 */
548 if ((ntd->td_mpcount && mpheld == 0 && !cpu_try_mplock()) ||
549 (ntd->td_toks && lwkt_chktokens(ntd) == 0)
550 ) {
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551 u_int32_t rqmask = gd->gd_runqmask;
552 while (rqmask) {
553 TAILQ_FOREACH(ntd, &gd->gd_tdrunq[nq], td_threadq) {
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554 if (ntd->td_mpcount && !mpheld && !cpu_try_mplock())
555 continue;
556 mpheld = MP_LOCK_HELD();
557 if (ntd->td_toks && !lwkt_chktokens(ntd))
558 continue;
559 break;
8a8d5d85
MD
560 }
561 if (ntd)
562 break;
563 rqmask &= ~(1 << nq);
564 nq = bsrl(rqmask);
565 }
566 if (ntd == NULL) {
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567 ntd = &gd->gd_idlethread;
568 ntd->td_flags |= TDF_IDLE_NOHLT;
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MD
569 } else {
570 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
571 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
572 }
573 } else {
574 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
575 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
576 }
577#else
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578 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
579 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
8a8d5d85 580#endif
4b5f931b 581 } else {
3c23a41a 582 /*
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583 * We have nothing to run but only let the idle loop halt
584 * the cpu if there are no pending interrupts.
3c23a41a 585 */
a2a5ad0d 586 ntd = &gd->gd_idlethread;
60f945af 587 if (gd->gd_reqflags & RQF_IDLECHECK_MASK)
3c23a41a 588 ntd->td_flags |= TDF_IDLE_NOHLT;
4b5f931b 589 }
f1d1c3fa 590 }
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MD
591 KASSERT(ntd->td_pri >= TDPRI_CRIT,
592 ("priority problem in lwkt_switch %d %d", td->td_pri, ntd->td_pri));
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MD
593
594 /*
595 * Do the actual switch. If the new target does not need the MP lock
596 * and we are holding it, release the MP lock. If the new target requires
597 * the MP lock we have already acquired it for the target.
598 */
599#ifdef SMP
600 if (ntd->td_mpcount == 0 ) {
601 if (MP_LOCK_HELD())
602 cpu_rel_mplock();
603 } else {
604 ASSERT_MP_LOCK_HELD();
605 }
606#endif
37af14fe 607 if (td != ntd)
f1d1c3fa 608 td->td_switch(ntd);
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609 /* NOTE: current cpu may have changed after switch */
610 crit_exit_quick(td);
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MD
611}
612
b68b7282 613/*
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614 * Request that the target thread preempt the current thread. Preemption
615 * only works under a specific set of conditions:
b68b7282 616 *
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617 * - We are not preempting ourselves
618 * - The target thread is owned by the current cpu
619 * - We are not currently being preempted
620 * - The target is not currently being preempted
621 * - We are able to satisfy the target's MP lock requirements (if any).
622 *
623 * THE CALLER OF LWKT_PREEMPT() MUST BE IN A CRITICAL SECTION. Typically
624 * this is called via lwkt_schedule() through the td_preemptable callback.
625 * critpri is the managed critical priority that we should ignore in order
626 * to determine whether preemption is possible (aka usually just the crit
627 * priority of lwkt_schedule() itself).
b68b7282 628 *
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629 * XXX at the moment we run the target thread in a critical section during
630 * the preemption in order to prevent the target from taking interrupts
631 * that *WE* can't. Preemption is strictly limited to interrupt threads
632 * and interrupt-like threads, outside of a critical section, and the
633 * preempted source thread will be resumed the instant the target blocks
634 * whether or not the source is scheduled (i.e. preemption is supposed to
635 * be as transparent as possible).
4b5f931b 636 *
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637 * The target thread inherits our MP count (added to its own) for the
638 * duration of the preemption in order to preserve the atomicy of the
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639 * MP lock during the preemption. Therefore, any preempting targets must be
640 * careful in regards to MP assertions. Note that the MP count may be
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641 * out of sync with the physical mp_lock, but we do not have to preserve
642 * the original ownership of the lock if it was out of synch (that is, we
643 * can leave it synchronized on return).
b68b7282
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644 */
645void
96728c05 646lwkt_preempt(thread_t ntd, int critpri)
b68b7282 647{
46a3f46d 648 struct globaldata *gd = mycpu;
0a3f9b47 649 thread_t td;
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650#ifdef SMP
651 int mpheld;
57c254db 652 int savecnt;
8a8d5d85 653#endif
b68b7282 654
26a0694b 655 /*
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656 * The caller has put us in a critical section. We can only preempt
657 * if the caller of the caller was not in a critical section (basically
0a3f9b47 658 * a local interrupt), as determined by the 'critpri' parameter.
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659 *
660 * YYY The target thread must be in a critical section (else it must
661 * inherit our critical section? I dunno yet).
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662 *
663 * Any tokens held by the target may not be held by thread(s) being
664 * preempted. We take the easy way out and do not preempt if
665 * the target is holding tokens.
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666 *
667 * Set need_lwkt_resched() unconditionally for now YYY.
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668 */
669 KASSERT(ntd->td_pri >= TDPRI_CRIT, ("BADCRIT0 %d", ntd->td_pri));
26a0694b 670
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671 td = gd->gd_curthread;
672 need_lwkt_resched();
673 if ((ntd->td_pri & TDPRI_MASK) <= (td->td_pri & TDPRI_MASK)) {
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MD
674 ++preempt_miss;
675 return;
676 }
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677 if ((td->td_pri & ~TDPRI_MASK) > critpri) {
678 ++preempt_miss;
679 return;
680 }
681#ifdef SMP
46a3f46d 682 if (ntd->td_gd != gd) {
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MD
683 ++preempt_miss;
684 return;
685 }
686#endif
41a01a4d
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687 /*
688 * Take the easy way out and do not preempt if the target is holding
689 * one or more tokens. We could test whether the thread(s) being
690 * preempted interlock against the target thread's tokens and whether
691 * we can get all the target thread's tokens, but this situation
692 * should not occur very often so its easier to simply not preempt.
693 */
694 if (ntd->td_toks != NULL) {
695 ++preempt_miss;
696 return;
697 }
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698 if (td == ntd || ((td->td_flags | ntd->td_flags) & TDF_PREEMPT_LOCK)) {
699 ++preempt_weird;
700 return;
701 }
702 if (ntd->td_preempted) {
4b5f931b 703 ++preempt_hit;
26a0694b 704 return;
b68b7282 705 }
8a8d5d85 706#ifdef SMP
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707 /*
708 * note: an interrupt might have occured just as we were transitioning
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709 * to or from the MP lock. In this case td_mpcount will be pre-disposed
710 * (non-zero) but not actually synchronized with the actual state of the
711 * lock. We can use it to imply an MP lock requirement for the
712 * preemption but we cannot use it to test whether we hold the MP lock
713 * or not.
a2a5ad0d 714 */
96728c05 715 savecnt = td->td_mpcount;
71ef2f5c 716 mpheld = MP_LOCK_HELD();
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717 ntd->td_mpcount += td->td_mpcount;
718 if (mpheld == 0 && ntd->td_mpcount && !cpu_try_mplock()) {
719 ntd->td_mpcount -= td->td_mpcount;
720 ++preempt_miss;
721 return;
722 }
723#endif
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MD
724
725 ++preempt_hit;
726 ntd->td_preempted = td;
727 td->td_flags |= TDF_PREEMPT_LOCK;
728 td->td_switch(ntd);
729 KKASSERT(ntd->td_preempted && (td->td_flags & TDF_PREEMPT_DONE));
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730#ifdef SMP
731 KKASSERT(savecnt == td->td_mpcount);
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MD
732 mpheld = MP_LOCK_HELD();
733 if (mpheld && td->td_mpcount == 0)
96728c05 734 cpu_rel_mplock();
71ef2f5c 735 else if (mpheld == 0 && td->td_mpcount)
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MD
736 panic("lwkt_preempt(): MP lock was not held through");
737#endif
26a0694b
MD
738 ntd->td_preempted = NULL;
739 td->td_flags &= ~(TDF_PREEMPT_LOCK|TDF_PREEMPT_DONE);
b68b7282
MD
740}
741
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MD
742/*
743 * Yield our thread while higher priority threads are pending. This is
744 * typically called when we leave a critical section but it can be safely
745 * called while we are in a critical section.
746 *
747 * This function will not generally yield to equal priority threads but it
748 * can occur as a side effect. Note that lwkt_switch() is called from
46a3f46d 749 * inside the critical section to prevent its own crit_exit() from reentering
f1d1c3fa
MD
750 * lwkt_yield_quick().
751 *
235957ed 752 * gd_reqflags indicates that *something* changed, e.g. an interrupt or softint
ef0fdad1
MD
753 * came along but was blocked and made pending.
754 *
f1d1c3fa
MD
755 * (self contained on a per cpu basis)
756 */
757void
758lwkt_yield_quick(void)
759{
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MD
760 globaldata_t gd = mycpu;
761 thread_t td = gd->gd_curthread;
ef0fdad1 762
a2a5ad0d 763 /*
235957ed 764 * gd_reqflags is cleared in splz if the cpl is 0. If we were to clear
a2a5ad0d
MD
765 * it with a non-zero cpl then we might not wind up calling splz after
766 * a task switch when the critical section is exited even though the
46a3f46d 767 * new task could accept the interrupt.
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MD
768 *
769 * XXX from crit_exit() only called after last crit section is released.
770 * If called directly will run splz() even if in a critical section.
46a3f46d
MD
771 *
772 * td_nest_count prevent deep nesting via splz() or doreti(). Note that
773 * except for this special case, we MUST call splz() here to handle any
774 * pending ints, particularly after we switch, or we might accidently
775 * halt the cpu with interrupts pending.
a2a5ad0d 776 */
46a3f46d 777 if (gd->gd_reqflags && td->td_nest_count < 2)
f1d1c3fa 778 splz();
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MD
779
780 /*
781 * YYY enabling will cause wakeup() to task-switch, which really
782 * confused the old 4.x code. This is a good way to simulate
7d0bac62
MD
783 * preemption and MP without actually doing preemption or MP, because a
784 * lot of code assumes that wakeup() does not block.
f1d1c3fa 785 */
46a3f46d
MD
786 if (untimely_switch && td->td_nest_count == 0 &&
787 gd->gd_intr_nesting_level == 0
788 ) {
37af14fe 789 crit_enter_quick(td);
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MD
790 /*
791 * YYY temporary hacks until we disassociate the userland scheduler
792 * from the LWKT scheduler.
793 */
794 if (td->td_flags & TDF_RUNQ) {
795 lwkt_switch(); /* will not reenter yield function */
796 } else {
37af14fe 797 lwkt_schedule_self(td); /* make sure we are scheduled */
f1d1c3fa 798 lwkt_switch(); /* will not reenter yield function */
37af14fe 799 lwkt_deschedule_self(td); /* make sure we are descheduled */
f1d1c3fa 800 }
7966cb69 801 crit_exit_noyield(td);
f1d1c3fa 802 }
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MD
803}
804
8ad65e08 805/*
f1d1c3fa 806 * This implements a normal yield which, unlike _quick, will yield to equal
235957ed 807 * priority threads as well. Note that gd_reqflags tests will be handled by
f1d1c3fa
MD
808 * the crit_exit() call in lwkt_switch().
809 *
810 * (self contained on a per cpu basis)
8ad65e08
MD
811 */
812void
f1d1c3fa 813lwkt_yield(void)
8ad65e08 814{
37af14fe 815 lwkt_schedule_self(curthread);
f1d1c3fa
MD
816 lwkt_switch();
817}
818
8ad65e08 819/*
f1d1c3fa
MD
820 * Generic schedule. Possibly schedule threads belonging to other cpus and
821 * deal with threads that might be blocked on a wait queue.
822 *
0a3f9b47
MD
823 * We have a little helper inline function which does additional work after
824 * the thread has been enqueued, including dealing with preemption and
825 * setting need_lwkt_resched() (which prevents the kernel from returning
826 * to userland until it has processed higher priority threads).
8ad65e08 827 */
0a3f9b47
MD
828static __inline
829void
830_lwkt_schedule_post(thread_t ntd, int cpri)
831{
832 if (ntd->td_preemptable) {
833 ntd->td_preemptable(ntd, cpri); /* YYY +token */
834 } else {
835 if ((ntd->td_flags & TDF_NORESCHED) == 0) {
836 if ((ntd->td_pri & TDPRI_MASK) >= TDPRI_KERN_USER)
837 need_lwkt_resched();
838 }
839 }
840}
841
8ad65e08
MD
842void
843lwkt_schedule(thread_t td)
844{
37af14fe
MD
845 globaldata_t mygd = mycpu;
846
96728c05 847#ifdef INVARIANTS
41a01a4d 848 KASSERT(td != &td->td_gd->gd_idlethread, ("lwkt_schedule(): scheduling gd_idlethread is illegal!"));
26a0694b
MD
849 if ((td->td_flags & TDF_PREEMPT_LOCK) == 0 && td->td_proc
850 && td->td_proc->p_stat == SSLEEP
851 ) {
852 printf("PANIC schedule curtd = %p (%d %d) target %p (%d %d)\n",
853 curthread,
854 curthread->td_proc ? curthread->td_proc->p_pid : -1,
855 curthread->td_proc ? curthread->td_proc->p_stat : -1,
856 td,
857 td->td_proc ? curthread->td_proc->p_pid : -1,
858 td->td_proc ? curthread->td_proc->p_stat : -1
859 );
860 panic("SCHED PANIC");
861 }
96728c05 862#endif
37af14fe
MD
863 crit_enter_gd(mygd);
864 if (td == mygd->gd_curthread) {
f1d1c3fa
MD
865 _lwkt_enqueue(td);
866 } else {
867 lwkt_wait_t w;
868
869 /*
870 * If the thread is on a wait list we have to send our scheduling
871 * request to the owner of the wait structure. Otherwise we send
872 * the scheduling request to the cpu owning the thread. Races
873 * are ok, the target will forward the message as necessary (the
874 * message may chase the thread around before it finally gets
875 * acted upon).
876 *
877 * (remember, wait structures use stable storage)
0a3f9b47
MD
878 *
879 * NOTE: tokens no longer enter a critical section, so we only need
880 * to account for the crit_enter() above when calling
881 * _lwkt_schedule_post().
f1d1c3fa
MD
882 */
883 if ((w = td->td_wait) != NULL) {
41a01a4d
MD
884 lwkt_tokref wref;
885
886 if (lwkt_trytoken(&wref, &w->wa_token)) {
f1d1c3fa
MD
887 TAILQ_REMOVE(&w->wa_waitq, td, td_threadq);
888 --w->wa_count;
889 td->td_wait = NULL;
0f7a3396
MD
890#ifdef SMP
891 if (td->td_gd == mycpu) {
f1d1c3fa 892 _lwkt_enqueue(td);
0a3f9b47 893 _lwkt_schedule_post(td, TDPRI_CRIT);
f1d1c3fa 894 } else {
2db3b277 895 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa 896 }
0f7a3396
MD
897#else
898 _lwkt_enqueue(td);
0a3f9b47 899 _lwkt_schedule_post(td, TDPRI_CRIT);
0f7a3396 900#endif
41a01a4d 901 lwkt_reltoken(&wref);
f1d1c3fa 902 } else {
96728c05 903 lwkt_send_ipiq(w->wa_token.t_cpu, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa
MD
904 }
905 } else {
906 /*
907 * If the wait structure is NULL and we own the thread, there
908 * is no race (since we are in a critical section). If we
909 * do not own the thread there might be a race but the
910 * target cpu will deal with it.
911 */
0f7a3396 912#ifdef SMP
37af14fe 913 if (td->td_gd == mygd) {
f1d1c3fa 914 _lwkt_enqueue(td);
0a3f9b47 915 _lwkt_schedule_post(td, TDPRI_CRIT);
f1d1c3fa 916 } else {
2db3b277 917 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa 918 }
0f7a3396
MD
919#else
920 _lwkt_enqueue(td);
0a3f9b47 921 _lwkt_schedule_post(td, TDPRI_CRIT);
0f7a3396 922#endif
f1d1c3fa 923 }
8ad65e08 924 }
37af14fe 925 crit_exit_gd(mygd);
8ad65e08
MD
926}
927
d9eea1a5
MD
928/*
929 * Managed acquisition. This code assumes that the MP lock is held for
930 * the tdallq operation and that the thread has been descheduled from its
931 * original cpu. We also have to wait for the thread to be entirely switched
932 * out on its original cpu (this is usually fast enough that we never loop)
933 * since the LWKT system does not have to hold the MP lock while switching
934 * and the target may have released it before switching.
935 */
a2a5ad0d
MD
936void
937lwkt_acquire(thread_t td)
938{
37af14fe
MD
939 globaldata_t gd;
940 globaldata_t mygd;
a2a5ad0d
MD
941
942 gd = td->td_gd;
37af14fe 943 mygd = mycpu;
a2a5ad0d 944 KKASSERT((td->td_flags & TDF_RUNQ) == 0);
d9eea1a5 945 while (td->td_flags & TDF_RUNNING) /* XXX spin */
5d21b981 946 cpu_mb1();
37af14fe
MD
947 if (gd != mygd) {
948 crit_enter_gd(mygd);
a2a5ad0d 949 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq); /* protected by BGL */
37af14fe
MD
950 td->td_gd = mygd;
951 TAILQ_INSERT_TAIL(&mygd->gd_tdallq, td, td_allq); /* protected by BGL */
952 crit_exit_gd(mygd);
a2a5ad0d
MD
953 }
954}
955
f1d1c3fa
MD
956/*
957 * Generic deschedule. Descheduling threads other then your own should be
958 * done only in carefully controlled circumstances. Descheduling is
959 * asynchronous.
960 *
961 * This function may block if the cpu has run out of messages.
8ad65e08
MD
962 */
963void
964lwkt_deschedule(thread_t td)
965{
f1d1c3fa
MD
966 crit_enter();
967 if (td == curthread) {
968 _lwkt_dequeue(td);
969 } else {
a72187e9 970 if (td->td_gd == mycpu) {
f1d1c3fa
MD
971 _lwkt_dequeue(td);
972 } else {
2db3b277 973 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_deschedule, td);
f1d1c3fa
MD
974 }
975 }
976 crit_exit();
977}
978
4b5f931b
MD
979/*
980 * Set the target thread's priority. This routine does not automatically
981 * switch to a higher priority thread, LWKT threads are not designed for
982 * continuous priority changes. Yield if you want to switch.
983 *
984 * We have to retain the critical section count which uses the high bits
26a0694b
MD
985 * of the td_pri field. The specified priority may also indicate zero or
986 * more critical sections by adding TDPRI_CRIT*N.
18bbe476
MD
987 *
988 * Note that we requeue the thread whether it winds up on a different runq
989 * or not. uio_yield() depends on this and the routine is not normally
990 * called with the same priority otherwise.
4b5f931b
MD
991 */
992void
993lwkt_setpri(thread_t td, int pri)
994{
26a0694b 995 KKASSERT(pri >= 0);
a72187e9 996 KKASSERT(td->td_gd == mycpu);
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MD
997 crit_enter();
998 if (td->td_flags & TDF_RUNQ) {
999 _lwkt_dequeue(td);
1000 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
1001 _lwkt_enqueue(td);
1002 } else {
1003 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
1004 }
1005 crit_exit();
1006}
1007
1008void
1009lwkt_setpri_self(int pri)
1010{
1011 thread_t td = curthread;
1012
4b5f931b
MD
1013 KKASSERT(pri >= 0 && pri <= TDPRI_MAX);
1014 crit_enter();
1015 if (td->td_flags & TDF_RUNQ) {
1016 _lwkt_dequeue(td);
1017 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
1018 _lwkt_enqueue(td);
1019 } else {
1020 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
1021 }
1022 crit_exit();
1023}
1024
5d21b981
MD
1025/*
1026 * Migrate the current thread to the specified cpu. The BGL must be held
1027 * (for the gd_tdallq manipulation XXX). This is accomplished by
1028 * descheduling ourselves from the current cpu, moving our thread to the
1029 * tdallq of the target cpu, IPI messaging the target cpu, and switching out.
1030 * TDF_MIGRATING prevents scheduling races while the thread is being migrated.
1031 */
3d28ff59 1032#ifdef SMP
5d21b981 1033static void lwkt_setcpu_remote(void *arg);
3d28ff59 1034#endif
5d21b981
MD
1035
1036void
1037lwkt_setcpu_self(globaldata_t rgd)
1038{
1039#ifdef SMP
1040 thread_t td = curthread;
1041
1042 if (td->td_gd != rgd) {
1043 crit_enter_quick(td);
1044 td->td_flags |= TDF_MIGRATING;
1045 lwkt_deschedule_self(td);
1046 TAILQ_REMOVE(&td->td_gd->gd_tdallq, td, td_allq); /* protected by BGL */
1047 TAILQ_INSERT_TAIL(&rgd->gd_tdallq, td, td_allq); /* protected by BGL */
1048 lwkt_send_ipiq(rgd, (ipifunc_t)lwkt_setcpu_remote, td);
1049 lwkt_switch();
1050 /* we are now on the target cpu */
1051 crit_exit_quick(td);
1052 }
1053#endif
1054}
1055
1056/*
1057 * Remote IPI for cpu migration (called while in a critical section so we
1058 * do not have to enter another one). The thread has already been moved to
1059 * our cpu's allq, but we must wait for the thread to be completely switched
1060 * out on the originating cpu before we schedule it on ours or the stack
1061 * state may be corrupt. We clear TDF_MIGRATING after flushing the GD
1062 * change to main memory.
1063 *
1064 * XXX The use of TDF_MIGRATING might not be sufficient to avoid races
1065 * against wakeups. It is best if this interface is used only when there
1066 * are no pending events that might try to schedule the thread.
1067 */
3d28ff59 1068#ifdef SMP
5d21b981
MD
1069static void
1070lwkt_setcpu_remote(void *arg)
1071{
1072 thread_t td = arg;
1073 globaldata_t gd = mycpu;
1074
1075 while (td->td_flags & TDF_RUNNING)
1076 cpu_mb1();
1077 td->td_gd = gd;
1078 cpu_mb2();
1079 td->td_flags &= ~TDF_MIGRATING;
1080 _lwkt_enqueue(td);
1081}
3d28ff59 1082#endif
5d21b981 1083
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1084struct proc *
1085lwkt_preempted_proc(void)
1086{
73e4f7b9 1087 thread_t td = curthread;
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1088 while (td->td_preempted)
1089 td = td->td_preempted;
1090 return(td->td_proc);
1091}
1092
f1d1c3fa 1093/*
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1094 * Block on the specified wait queue until signaled. A generation number
1095 * must be supplied to interlock the wait queue. The function will
1096 * return immediately if the generation number does not match the wait
1097 * structure's generation number.
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1098 */
1099void
ae8050a4 1100lwkt_block(lwkt_wait_t w, const char *wmesg, int *gen)
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1101{
1102 thread_t td = curthread;
41a01a4d 1103 lwkt_tokref ilock;
f1d1c3fa 1104
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1105 lwkt_gettoken(&ilock, &w->wa_token);
1106 crit_enter();
ae8050a4 1107 if (w->wa_gen == *gen) {
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1108 _lwkt_dequeue(td);
1109 TAILQ_INSERT_TAIL(&w->wa_waitq, td, td_threadq);
1110 ++w->wa_count;
1111 td->td_wait = w;
ae8050a4 1112 td->td_wmesg = wmesg;
41a01a4d 1113 again:
f1d1c3fa 1114 lwkt_switch();
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1115 if (td->td_wmesg != NULL) {
1116 _lwkt_dequeue(td);
1117 goto again;
1118 }
8ad65e08 1119 }
41a01a4d 1120 crit_exit();
ae8050a4 1121 *gen = w->wa_gen;
41a01a4d 1122 lwkt_reltoken(&ilock);
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1123}
1124
1125/*
1126 * Signal a wait queue. We gain ownership of the wait queue in order to
1127 * signal it. Once a thread is removed from the wait queue we have to
1128 * deal with the cpu owning the thread.
1129 *
1130 * Note: alternatively we could message the target cpu owning the wait
1131 * queue. YYY implement as sysctl.
1132 */
1133void
ece04fd0 1134lwkt_signal(lwkt_wait_t w, int count)
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1135{
1136 thread_t td;
41a01a4d 1137 lwkt_tokref ilock;
f1d1c3fa 1138
41a01a4d 1139 lwkt_gettoken(&ilock, &w->wa_token);
f1d1c3fa 1140 ++w->wa_gen;
41a01a4d 1141 crit_enter();
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1142 if (count < 0)
1143 count = w->wa_count;
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1144 while ((td = TAILQ_FIRST(&w->wa_waitq)) != NULL && count) {
1145 --count;
1146 --w->wa_count;
1147 TAILQ_REMOVE(&w->wa_waitq, td, td_threadq);
1148 td->td_wait = NULL;
ae8050a4 1149 td->td_wmesg = NULL;
a72187e9 1150 if (td->td_gd == mycpu) {
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1151 _lwkt_enqueue(td);
1152 } else {
2db3b277 1153 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa 1154 }
f1d1c3fa 1155 }
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1156 crit_exit();
1157 lwkt_reltoken(&ilock);
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1158}
1159
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1160/*
1161 * Create a kernel process/thread/whatever. It shares it's address space
1162 * with proc0 - ie: kernel only.
1163 *
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1164 * NOTE! By default new threads are created with the MP lock held. A
1165 * thread which does not require the MP lock should release it by calling
1166 * rel_mplock() at the start of the new thread.
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1167 */
1168int
1169lwkt_create(void (*func)(void *), void *arg,
75cdbe6c 1170 struct thread **tdp, thread_t template, int tdflags, int cpu,
ef0fdad1 1171 const char *fmt, ...)
99df837e 1172{
73e4f7b9 1173 thread_t td;
e2565a42 1174 __va_list ap;
99df837e 1175
75cdbe6c 1176 td = lwkt_alloc_thread(template, cpu);
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1177 if (tdp)
1178 *tdp = td;
709799ea 1179 cpu_set_thread_handler(td, lwkt_exit, func, arg);
ef0fdad1 1180 td->td_flags |= TDF_VERBOSE | tdflags;
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1181#ifdef SMP
1182 td->td_mpcount = 1;
1183#endif
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1184
1185 /*
1186 * Set up arg0 for 'ps' etc
1187 */
e2565a42 1188 __va_start(ap, fmt);
99df837e 1189 vsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
e2565a42 1190 __va_end(ap);
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1191
1192 /*
1193 * Schedule the thread to run
1194 */
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1195 if ((td->td_flags & TDF_STOPREQ) == 0)
1196 lwkt_schedule(td);
1197 else
1198 td->td_flags &= ~TDF_STOPREQ;
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1199 return 0;
1200}
1201
2d93b37a 1202/*
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1203 * kthread_* is specific to the kernel and is not needed by userland.
1204 */
1205#ifdef _KERNEL
1206
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1207/*
1208 * Destroy an LWKT thread. Warning! This function is not called when
1209 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
1210 * uses a different reaping mechanism.
1211 */
1212void
1213lwkt_exit(void)
1214{
1215 thread_t td = curthread;
8826f33a 1216 globaldata_t gd;
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1217
1218 if (td->td_flags & TDF_VERBOSE)
1219 printf("kthread %p %s has exited\n", td, td->td_comm);
f6bf3af1 1220 caps_exit(td);
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1221 crit_enter_quick(td);
1222 lwkt_deschedule_self(td);
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1223 gd = mycpu;
1224 KKASSERT(gd == td->td_gd);
1225 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq);
1226 if (td->td_flags & TDF_ALLOCATED_THREAD) {
1227 ++gd->gd_tdfreecount;
1228 TAILQ_INSERT_TAIL(&gd->gd_tdfreeq, td, td_threadq);
1229 }
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1230 cpu_thread_exit();
1231}
1232
1233/*
1234 * Create a kernel process/thread/whatever. It shares it's address space
ef0fdad1 1235 * with proc0 - ie: kernel only. 5.x compatible.
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1236 *
1237 * NOTE! By default kthreads are created with the MP lock held. A
1238 * thread which does not require the MP lock should release it by calling
1239 * rel_mplock() at the start of the new thread.
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1240 */
1241int
1242kthread_create(void (*func)(void *), void *arg,
1243 struct thread **tdp, const char *fmt, ...)
1244{
73e4f7b9 1245 thread_t td;
e2565a42 1246 __va_list ap;
99df837e 1247
75cdbe6c 1248 td = lwkt_alloc_thread(NULL, -1);
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1249 if (tdp)
1250 *tdp = td;
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1251 cpu_set_thread_handler(td, kthread_exit, func, arg);
1252 td->td_flags |= TDF_VERBOSE;
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1253#ifdef SMP
1254 td->td_mpcount = 1;
1255#endif
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1256
1257 /*
1258 * Set up arg0 for 'ps' etc
1259 */
e2565a42 1260 __va_start(ap, fmt);
99df837e 1261 vsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
e2565a42 1262 __va_end(ap);
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1263
1264 /*
1265 * Schedule the thread to run
1266 */
1267 lwkt_schedule(td);
1268 return 0;
1269}
1270
1271/*
1272 * Destroy an LWKT thread. Warning! This function is not called when
1273 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
1274 * uses a different reaping mechanism.
1275 *
1276 * XXX duplicates lwkt_exit()
1277 */
1278void
1279kthread_exit(void)
1280{
1281 lwkt_exit();
1282}
1283
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1284#endif /* _KERNEL */
1285
1286void
1287crit_panic(void)
1288{
1289 thread_t td = curthread;
1290 int lpri = td->td_pri;
1291
1292 td->td_pri = 0;
1293 panic("td_pri is/would-go negative! %p %d", td, lpri);
1294}
1295