Misc interrupts/LWKT 1/2: interlock the idle thread. Put execution of
[dragonfly.git] / sys / kern / lwkt_thread.c
CommitLineData
8ad65e08
MD
1/*
2 * Copyright (c) 2003 Matthew Dillon <dillon@backplane.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
f1d1c3fa
MD
26 * Each cpu in a system has its own self-contained light weight kernel
27 * thread scheduler, which means that generally speaking we only need
28 * to use a critical section to prevent hicups.
29 *
4b5f931b 30 * $DragonFly: src/sys/kern/lwkt_thread.c,v 1.11 2003/06/29 07:37:06 dillon Exp $
8ad65e08
MD
31 */
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/kernel.h>
36#include <sys/proc.h>
37#include <sys/rtprio.h>
38#include <sys/queue.h>
f1d1c3fa 39#include <sys/thread2.h>
7d0bac62 40#include <sys/sysctl.h>
99df837e 41#include <sys/kthread.h>
f1d1c3fa 42#include <machine/cpu.h>
99df837e 43#include <sys/lock.h>
f1d1c3fa 44
7d0bac62
MD
45#include <vm/vm.h>
46#include <vm/vm_param.h>
47#include <vm/vm_kern.h>
48#include <vm/vm_object.h>
49#include <vm/vm_page.h>
50#include <vm/vm_map.h>
51#include <vm/vm_pager.h>
52#include <vm/vm_extern.h>
53#include <vm/vm_zone.h>
54
99df837e
MD
55#include <machine/stdarg.h>
56
7d0bac62 57static int untimely_switch = 0;
4b5f931b
MD
58SYSCTL_INT(_lwkt, OID_AUTO, untimely_switch, CTLFLAG_RW, &untimely_switch, 0, "");
59static quad_t switch_count = 0;
60SYSCTL_QUAD(_lwkt, OID_AUTO, switch_count, CTLFLAG_RW, &switch_count, 0, "");
61static quad_t preempt_hit = 0;
62SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_hit, CTLFLAG_RW, &preempt_hit, 0, "");
63static quad_t preempt_miss = 0;
64SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_miss, CTLFLAG_RW, &preempt_miss, 0, "");
7d0bac62 65
4b5f931b
MD
66/*
67 * These helper procedures handle the runq, they can only be called from
68 * within a critical section.
69 */
f1d1c3fa
MD
70static __inline
71void
72_lwkt_dequeue(thread_t td)
73{
74 if (td->td_flags & TDF_RUNQ) {
4b5f931b
MD
75 int nq = td->td_pri & TDPRI_MASK;
76 struct globaldata *gd = mycpu;
77
f1d1c3fa 78 td->td_flags &= ~TDF_RUNQ;
4b5f931b
MD
79 TAILQ_REMOVE(&gd->gd_tdrunq[nq], td, td_threadq);
80 /* runqmask is passively cleaned up by the switcher */
f1d1c3fa
MD
81 }
82}
83
84static __inline
85void
86_lwkt_enqueue(thread_t td)
87{
88 if ((td->td_flags & TDF_RUNQ) == 0) {
4b5f931b
MD
89 int nq = td->td_pri & TDPRI_MASK;
90 struct globaldata *gd = mycpu;
91
f1d1c3fa 92 td->td_flags |= TDF_RUNQ;
4b5f931b
MD
93 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], td, td_threadq);
94 gd->gd_runqmask |= 1 << nq;
f1d1c3fa
MD
95 }
96}
8ad65e08
MD
97
98/*
99 * LWKTs operate on a per-cpu basis
100 *
101 * YYY implement strict priorities & round-robin at the same priority
102 */
103void
104lwkt_gdinit(struct globaldata *gd)
105{
4b5f931b
MD
106 int i;
107
108 for (i = 0; i < sizeof(gd->gd_tdrunq)/sizeof(gd->gd_tdrunq[0]); ++i)
109 TAILQ_INIT(&gd->gd_tdrunq[i]);
110 gd->gd_runqmask = 0;
8ad65e08
MD
111}
112
7d0bac62
MD
113/*
114 * Initialize a thread wait structure prior to first use.
115 *
116 * NOTE! called from low level boot code, we cannot do anything fancy!
117 */
118void
119lwkt_init_wait(lwkt_wait_t w)
120{
121 TAILQ_INIT(&w->wa_waitq);
122}
123
124/*
125 * Create a new thread. The thread must be associated with a process context
126 * or LWKT start address before it can be scheduled.
0cfcada1
MD
127 *
128 * If you intend to create a thread without a process context this function
129 * does everything except load the startup and switcher function.
7d0bac62
MD
130 */
131thread_t
ef0fdad1 132lwkt_alloc_thread(struct thread *td)
7d0bac62 133{
99df837e 134 void *stack;
ef0fdad1 135 int flags = 0;
7d0bac62 136
99df837e 137 crit_enter();
ef0fdad1
MD
138 if (td == NULL) {
139 if (mycpu->gd_tdfreecount > 0) {
140 --mycpu->gd_tdfreecount;
141 td = TAILQ_FIRST(&mycpu->gd_tdfreeq);
142 KASSERT(td != NULL && (td->td_flags & TDF_EXITED),
143 ("lwkt_alloc_thread: unexpected NULL or corrupted td"));
144 TAILQ_REMOVE(&mycpu->gd_tdfreeq, td, td_threadq);
145 crit_exit();
146 stack = td->td_kstack;
147 flags = td->td_flags & (TDF_ALLOCATED_STACK|TDF_ALLOCATED_THREAD);
148 } else {
149 crit_exit();
150 td = zalloc(thread_zone);
151 td->td_kstack = NULL;
152 flags |= TDF_ALLOCATED_THREAD;
153 }
154 }
155 if ((stack = td->td_kstack) == NULL) {
99df837e 156 stack = (void *)kmem_alloc(kernel_map, UPAGES * PAGE_SIZE);
ef0fdad1 157 flags |= TDF_ALLOCATED_STACK;
99df837e 158 }
ef0fdad1 159 lwkt_init_thread(td, stack, flags);
99df837e 160 return(td);
7d0bac62
MD
161}
162
163/*
164 * Initialize a preexisting thread structure. This function is used by
165 * lwkt_alloc_thread() and also used to initialize the per-cpu idlethread.
166 *
167 * NOTE! called from low level boot code, we cannot do anything fancy!
168 */
169void
99df837e 170lwkt_init_thread(thread_t td, void *stack, int flags)
7d0bac62 171{
99df837e
MD
172 bzero(td, sizeof(struct thread));
173 td->td_kstack = stack;
174 td->td_flags |= flags;
175 pmap_init_thread(td);
7d0bac62
MD
176}
177
99df837e
MD
178void
179lwkt_free_thread(struct thread *td)
180{
181 KASSERT(td->td_flags & TDF_EXITED,
182 ("lwkt_free_thread: did not exit! %p", td));
183
184 crit_enter();
185 if (mycpu->gd_tdfreecount < CACHE_NTHREADS &&
186 (td->td_flags & TDF_ALLOCATED_THREAD)
187 ) {
188 ++mycpu->gd_tdfreecount;
189 TAILQ_INSERT_HEAD(&mycpu->gd_tdfreeq, td, td_threadq);
190 crit_exit();
191 } else {
192 crit_exit();
193 if (td->td_kstack && (td->td_flags & TDF_ALLOCATED_STACK)) {
194 kmem_free(kernel_map,
195 (vm_offset_t)td->td_kstack, UPAGES * PAGE_SIZE);
196 td->td_kstack = NULL;
197 }
198 if (td->td_flags & TDF_ALLOCATED_THREAD)
199 zfree(thread_zone, td);
200 }
201}
202
203
8ad65e08
MD
204/*
205 * Switch to the next runnable lwkt. If no LWKTs are runnable then
f1d1c3fa
MD
206 * switch to the idlethread. Switching must occur within a critical
207 * section to avoid races with the scheduling queue.
208 *
209 * We always have full control over our cpu's run queue. Other cpus
210 * that wish to manipulate our queue must use the cpu_*msg() calls to
211 * talk to our cpu, so a critical section is all that is needed and
212 * the result is very, very fast thread switching.
213 *
214 * We always 'own' our own thread and the threads on our run queue,l
215 * due to TDF_RUNNING or TDF_RUNQ being set. We can safely clear
216 * TDF_RUNNING while in a critical section.
217 *
218 * The td_switch() function must be called while in the critical section.
219 * This function saves as much state as is appropriate for the type of
220 * thread.
221 *
222 * (self contained on a per cpu basis)
8ad65e08
MD
223 */
224void
225lwkt_switch(void)
226{
4b5f931b 227 struct globaldata *gd;
f1d1c3fa 228 thread_t td = curthread;
8ad65e08
MD
229 thread_t ntd;
230
b68b7282 231 if (mycpu->gd_intr_nesting_level && td->td_preempted == NULL)
ef0fdad1
MD
232 panic("lwkt_switch: cannot switch from within an interrupt\n");
233
f1d1c3fa 234 crit_enter();
4b5f931b 235 ++switch_count;
99df837e
MD
236 if ((ntd = td->td_preempted) != NULL) {
237 /*
238 * We had preempted another thread on this cpu, resume the preempted
239 * thread.
240 */
241 td->td_preempted = NULL;
b68b7282 242 td->td_pri -= TDPRI_CRIT;
99df837e 243 ntd->td_flags &= ~TDF_PREEMPTED;
8ad65e08 244 } else {
4b5f931b
MD
245 /*
246 * Priority queue / round-robin at each priority. Note that user
247 * processes run at a fixed, low priority and the user process
248 * scheduler deals with interactions between user processes
249 * by scheduling and descheduling them from the LWKT queue as
250 * necessary.
251 */
252 gd = mycpu;
253
254again:
255 if (gd->gd_runqmask) {
256 int nq = bsrl(gd->gd_runqmask);
257 if ((ntd = TAILQ_FIRST(&gd->gd_tdrunq[nq])) == NULL) {
258 gd->gd_runqmask &= ~(1 << nq);
259 goto again;
260 }
261 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
262 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
263 } else {
264 ntd = gd->gd_idletd;
265 }
f1d1c3fa 266 }
99df837e 267 if (td != ntd)
f1d1c3fa 268 td->td_switch(ntd);
f1d1c3fa 269 crit_exit();
8ad65e08
MD
270}
271
b68b7282
MD
272/*
273 * The target thread preempts the current thread. The target thread
274 * structure must be stable and preempt-safe (e.g. an interrupt thread).
275 * When the target thread blocks the current thread will be resumed.
276 *
277 * XXX the target runs in a critical section so it does not open the original
278 * thread up to additional interrupts that the original thread believes it
279 * is blocking.
280 *
281 * Normal kernel threads should not preempt other normal kernel threads
282 * as it breaks the assumptions kernel threads are allowed to make. Note
283 * that preemption does not mess around with the current thread's RUNQ
284 * state.
4b5f931b
MD
285 *
286 * This call is typically made from an interrupt handler like sched_ithd()
287 * which will only run if the current thread is not in a critical section,
288 * so we optimize the priority check a bit.
b68b7282
MD
289 */
290void
291lwkt_preempt(struct thread *ntd, int id)
292{
293 struct thread *td = curthread;
294
4b5f931b
MD
295 crit_enter(); /* YYY token */
296 if (ntd->td_preempted == NULL &&
297 (ntd->td_pri & TDPRI_MASK) > (td->td_pri & TDPRI_MASK)
298 ) {
299 ++preempt_hit;
300 ntd->td_preempted = td;
b68b7282
MD
301 td->td_flags |= TDF_PREEMPTED;
302 ntd->td_pri += TDPRI_CRIT;
303 while (td->td_flags & TDF_PREEMPTED)
304 ntd->td_switch(ntd);
4b5f931b
MD
305 } else {
306 ++preempt_miss;
b68b7282
MD
307 }
308 crit_exit_noyield();
309}
310
f1d1c3fa
MD
311/*
312 * Yield our thread while higher priority threads are pending. This is
313 * typically called when we leave a critical section but it can be safely
314 * called while we are in a critical section.
315 *
316 * This function will not generally yield to equal priority threads but it
317 * can occur as a side effect. Note that lwkt_switch() is called from
318 * inside the critical section to pervent its own crit_exit() from reentering
319 * lwkt_yield_quick().
320 *
ef0fdad1
MD
321 * gd_reqpri indicates that *something* changed, e.g. an interrupt or softint
322 * came along but was blocked and made pending.
323 *
f1d1c3fa
MD
324 * (self contained on a per cpu basis)
325 */
326void
327lwkt_yield_quick(void)
328{
329 thread_t td = curthread;
ef0fdad1
MD
330
331 if ((td->td_pri & TDPRI_MASK) < mycpu->gd_reqpri) {
332 mycpu->gd_reqpri = 0;
f1d1c3fa
MD
333 splz();
334 }
335
336 /*
337 * YYY enabling will cause wakeup() to task-switch, which really
338 * confused the old 4.x code. This is a good way to simulate
7d0bac62
MD
339 * preemption and MP without actually doing preemption or MP, because a
340 * lot of code assumes that wakeup() does not block.
f1d1c3fa 341 */
ef0fdad1 342 if (untimely_switch && mycpu->gd_intr_nesting_level == 0) {
f1d1c3fa
MD
343 crit_enter();
344 /*
345 * YYY temporary hacks until we disassociate the userland scheduler
346 * from the LWKT scheduler.
347 */
348 if (td->td_flags & TDF_RUNQ) {
349 lwkt_switch(); /* will not reenter yield function */
350 } else {
351 lwkt_schedule_self(); /* make sure we are scheduled */
352 lwkt_switch(); /* will not reenter yield function */
353 lwkt_deschedule_self(); /* make sure we are descheduled */
354 }
355 crit_exit_noyield();
356 }
f1d1c3fa
MD
357}
358
8ad65e08 359/*
f1d1c3fa
MD
360 * This implements a normal yield which, unlike _quick, will yield to equal
361 * priority threads as well. Note that gd_reqpri tests will be handled by
362 * the crit_exit() call in lwkt_switch().
363 *
364 * (self contained on a per cpu basis)
8ad65e08
MD
365 */
366void
f1d1c3fa 367lwkt_yield(void)
8ad65e08 368{
f1d1c3fa
MD
369 lwkt_schedule_self();
370 lwkt_switch();
371}
372
373/*
374 * Schedule a thread to run. As the current thread we can always safely
375 * schedule ourselves, and a shortcut procedure is provided for that
376 * function.
377 *
378 * (non-blocking, self contained on a per cpu basis)
379 */
380void
381lwkt_schedule_self(void)
382{
383 thread_t td = curthread;
384
385 crit_enter();
386 KASSERT(td->td_wait == NULL, ("lwkt_schedule_self(): td_wait not NULL!"));
f1d1c3fa
MD
387 _lwkt_enqueue(td);
388 crit_exit();
8ad65e08 389}
8ad65e08
MD
390
391/*
f1d1c3fa
MD
392 * Generic schedule. Possibly schedule threads belonging to other cpus and
393 * deal with threads that might be blocked on a wait queue.
394 *
395 * This function will queue requests asynchronously when possible, but may
396 * block if no request structures are available. Upon return the caller
397 * should note that the scheduling request may not yet have been processed
398 * by the target cpu.
399 *
400 * YYY this is one of the best places to implement any load balancing code.
401 * Load balancing can be accomplished by requesting other sorts of actions
402 * for the thread in question.
8ad65e08
MD
403 */
404void
405lwkt_schedule(thread_t td)
406{
f1d1c3fa
MD
407 crit_enter();
408 if (td == curthread) {
409 _lwkt_enqueue(td);
410 } else {
411 lwkt_wait_t w;
412
413 /*
414 * If the thread is on a wait list we have to send our scheduling
415 * request to the owner of the wait structure. Otherwise we send
416 * the scheduling request to the cpu owning the thread. Races
417 * are ok, the target will forward the message as necessary (the
418 * message may chase the thread around before it finally gets
419 * acted upon).
420 *
421 * (remember, wait structures use stable storage)
422 */
423 if ((w = td->td_wait) != NULL) {
424 if (lwkt_havetoken(&w->wa_token)) {
425 TAILQ_REMOVE(&w->wa_waitq, td, td_threadq);
426 --w->wa_count;
427 td->td_wait = NULL;
d0e06f83 428 if (td->td_cpu == mycpu->gd_cpuid) {
f1d1c3fa
MD
429 _lwkt_enqueue(td);
430 } else {
431 panic("lwkt_schedule: cpu mismatch1");
8ad65e08 432#if 0
f1d1c3fa
MD
433 lwkt_cpu_msg_union_t msg = lwkt_getcpumsg();
434 initScheduleReqMsg_Wait(&msg.mu_SchedReq, td, w);
435 cpu_sendnormsg(&msg.mu_Msg);
8ad65e08 436#endif
f1d1c3fa
MD
437 }
438 } else {
439 panic("lwkt_schedule: cpu mismatch2");
440#if 0
441 lwkt_cpu_msg_union_t msg = lwkt_getcpumsg();
442 initScheduleReqMsg_Wait(&msg.mu_SchedReq, td, w);
443 cpu_sendnormsg(&msg.mu_Msg);
444#endif
445 }
446 } else {
447 /*
448 * If the wait structure is NULL and we own the thread, there
449 * is no race (since we are in a critical section). If we
450 * do not own the thread there might be a race but the
451 * target cpu will deal with it.
452 */
d0e06f83 453 if (td->td_cpu == mycpu->gd_cpuid) {
f1d1c3fa
MD
454 _lwkt_enqueue(td);
455 } else {
456 panic("lwkt_schedule: cpu mismatch3");
457#if 0
458 lwkt_cpu_msg_union_t msg = lwkt_getcpumsg();
459 initScheduleReqMsg_Thread(&msg.mu_SchedReq, td);
460 cpu_sendnormsg(&msg.mu_Msg);
461#endif
462 }
463 }
8ad65e08 464 }
f1d1c3fa 465 crit_exit();
8ad65e08
MD
466}
467
468/*
f1d1c3fa
MD
469 * Deschedule a thread.
470 *
471 * (non-blocking, self contained on a per cpu basis)
472 */
473void
474lwkt_deschedule_self(void)
475{
476 thread_t td = curthread;
477
478 crit_enter();
479 KASSERT(td->td_wait == NULL, ("lwkt_schedule_self(): td_wait not NULL!"));
f1d1c3fa
MD
480 _lwkt_dequeue(td);
481 crit_exit();
482}
483
484/*
485 * Generic deschedule. Descheduling threads other then your own should be
486 * done only in carefully controlled circumstances. Descheduling is
487 * asynchronous.
488 *
489 * This function may block if the cpu has run out of messages.
8ad65e08
MD
490 */
491void
492lwkt_deschedule(thread_t td)
493{
f1d1c3fa
MD
494 crit_enter();
495 if (td == curthread) {
496 _lwkt_dequeue(td);
497 } else {
d0e06f83 498 if (td->td_cpu == mycpu->gd_cpuid) {
f1d1c3fa
MD
499 _lwkt_dequeue(td);
500 } else {
501 panic("lwkt_deschedule: cpu mismatch");
502#if 0
503 lwkt_cpu_msg_union_t msg = lwkt_getcpumsg();
504 initDescheduleReqMsg_Thread(&msg.mu_DeschedReq, td);
505 cpu_sendnormsg(&msg.mu_Msg);
506#endif
507 }
508 }
509 crit_exit();
510}
511
4b5f931b
MD
512/*
513 * Set the target thread's priority. This routine does not automatically
514 * switch to a higher priority thread, LWKT threads are not designed for
515 * continuous priority changes. Yield if you want to switch.
516 *
517 * We have to retain the critical section count which uses the high bits
518 * of the td_pri field.
519 */
520void
521lwkt_setpri(thread_t td, int pri)
522{
523 KKASSERT(pri >= 0 && pri <= TDPRI_MAX);
524 crit_enter();
525 if (td->td_flags & TDF_RUNQ) {
526 _lwkt_dequeue(td);
527 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
528 _lwkt_enqueue(td);
529 } else {
530 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
531 }
532 crit_exit();
533}
534
535struct proc *
536lwkt_preempted_proc(void)
537{
538 struct thread *td = curthread;
539 while (td->td_preempted)
540 td = td->td_preempted;
541 return(td->td_proc);
542}
543
544
f1d1c3fa
MD
545/*
546 * This function deschedules the current thread and blocks on the specified
547 * wait queue. We obtain ownership of the wait queue in order to block
548 * on it. A generation number is used to interlock the wait queue in case
549 * it gets signalled while we are blocked waiting on the token.
550 *
551 * Note: alternatively we could dequeue our thread and then message the
552 * target cpu owning the wait queue. YYY implement as sysctl.
553 *
554 * Note: wait queue signals normally ping-pong the cpu as an optimization.
555 */
556void
ae8050a4 557lwkt_block(lwkt_wait_t w, const char *wmesg, int *gen)
f1d1c3fa
MD
558{
559 thread_t td = curthread;
f1d1c3fa 560
f1d1c3fa 561 lwkt_gettoken(&w->wa_token);
ae8050a4 562 if (w->wa_gen == *gen) {
f1d1c3fa
MD
563 _lwkt_dequeue(td);
564 TAILQ_INSERT_TAIL(&w->wa_waitq, td, td_threadq);
565 ++w->wa_count;
566 td->td_wait = w;
ae8050a4 567 td->td_wmesg = wmesg;
f1d1c3fa 568 lwkt_switch();
8ad65e08 569 }
ae8050a4
MD
570 /* token might be lost, doesn't matter for gen update */
571 *gen = w->wa_gen;
f1d1c3fa
MD
572 lwkt_reltoken(&w->wa_token);
573}
574
575/*
576 * Signal a wait queue. We gain ownership of the wait queue in order to
577 * signal it. Once a thread is removed from the wait queue we have to
578 * deal with the cpu owning the thread.
579 *
580 * Note: alternatively we could message the target cpu owning the wait
581 * queue. YYY implement as sysctl.
582 */
583void
584lwkt_signal(lwkt_wait_t w)
585{
586 thread_t td;
587 int count;
588
589 lwkt_gettoken(&w->wa_token);
590 ++w->wa_gen;
591 count = w->wa_count;
592 while ((td = TAILQ_FIRST(&w->wa_waitq)) != NULL && count) {
593 --count;
594 --w->wa_count;
595 TAILQ_REMOVE(&w->wa_waitq, td, td_threadq);
596 td->td_wait = NULL;
ae8050a4 597 td->td_wmesg = NULL;
d0e06f83 598 if (td->td_cpu == mycpu->gd_cpuid) {
f1d1c3fa
MD
599 _lwkt_enqueue(td);
600 } else {
601#if 0
602 lwkt_cpu_msg_union_t msg = lwkt_getcpumsg();
603 initScheduleReqMsg_Thread(&msg.mu_SchedReq, td);
604 cpu_sendnormsg(&msg.mu_Msg);
605#endif
606 panic("lwkt_signal: cpu mismatch");
607 }
608 lwkt_regettoken(&w->wa_token);
609 }
610 lwkt_reltoken(&w->wa_token);
611}
612
613/*
614 * Aquire ownership of a token
615 *
616 * Aquire ownership of a token. The token may have spl and/or critical
617 * section side effects, depending on its purpose. These side effects
618 * guarentee that you will maintain ownership of the token as long as you
619 * do not block. If you block you may lose access to the token (but you
620 * must still release it even if you lose your access to it).
621 *
622 * Note that the spl and critical section characteristics of a token
623 * may not be changed once the token has been initialized.
624 */
625void
626lwkt_gettoken(lwkt_token_t tok)
627{
628 /*
629 * Prevent preemption so the token can't be taken away from us once
630 * we gain ownership of it. Use a synchronous request which might
631 * block. The request will be forwarded as necessary playing catchup
632 * to the token.
633 */
634 crit_enter();
635#if 0
d0e06f83 636 while (tok->t_cpu != mycpu->gd_cpuid) {
f1d1c3fa
MD
637 lwkt_cpu_msg_union msg;
638 initTokenReqMsg(&msg.mu_TokenReq);
639 cpu_domsg(&msg);
640 }
641#endif
642 /*
643 * leave us in a critical section on return. This will be undone
644 * by lwkt_reltoken()
645 */
646}
647
648/*
649 * Release your ownership of a token. Releases must occur in reverse
650 * order to aquisitions, eventually so priorities can be unwound properly
651 * like SPLs. At the moment the actual implemention doesn't care.
652 *
653 * We can safely hand a token that we own to another cpu without notifying
654 * it, but once we do we can't get it back without requesting it (unless
655 * the other cpu hands it back to us before we check).
656 *
657 * We might have lost the token, so check that.
658 */
659void
660lwkt_reltoken(lwkt_token_t tok)
661{
d0e06f83 662 if (tok->t_cpu == mycpu->gd_cpuid) {
f1d1c3fa
MD
663 tok->t_cpu = tok->t_reqcpu;
664 }
665 crit_exit();
666}
667
668/*
669 * Reaquire a token that might have been lost. Returns 1 if we blocked
670 * while reaquiring the token (meaning that you might have lost other
671 * tokens you held when you made this call), return 0 if we did not block.
672 */
673int
674lwkt_regettoken(lwkt_token_t tok)
675{
676#if 0
d0e06f83
MD
677 if (tok->t_cpu != mycpu->gd_cpuid) {
678 while (tok->t_cpu != mycpu->gd_cpuid) {
f1d1c3fa
MD
679 lwkt_cpu_msg_union msg;
680 initTokenReqMsg(&msg.mu_TokenReq);
681 cpu_domsg(&msg);
682 }
683 return(1);
684 }
685#endif
686 return(0);
8ad65e08
MD
687}
688
99df837e
MD
689/*
690 * Create a kernel process/thread/whatever. It shares it's address space
691 * with proc0 - ie: kernel only.
692 *
693 * XXX should be renamed to lwkt_create()
694 */
695int
696lwkt_create(void (*func)(void *), void *arg,
ef0fdad1
MD
697 struct thread **tdp, struct thread *template, int tdflags,
698 const char *fmt, ...)
99df837e
MD
699{
700 struct thread *td;
701 va_list ap;
702
ef0fdad1 703 td = *tdp = lwkt_alloc_thread(template);
99df837e 704 cpu_set_thread_handler(td, kthread_exit, func, arg);
ef0fdad1 705 td->td_flags |= TDF_VERBOSE | tdflags;
99df837e
MD
706
707 /*
708 * Set up arg0 for 'ps' etc
709 */
710 va_start(ap, fmt);
711 vsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
712 va_end(ap);
713
714 /*
715 * Schedule the thread to run
716 */
ef0fdad1
MD
717 if ((td->td_flags & TDF_STOPREQ) == 0)
718 lwkt_schedule(td);
719 else
720 td->td_flags &= ~TDF_STOPREQ;
99df837e
MD
721 return 0;
722}
723
724/*
725 * Destroy an LWKT thread. Warning! This function is not called when
726 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
727 * uses a different reaping mechanism.
728 */
729void
730lwkt_exit(void)
731{
732 thread_t td = curthread;
733
734 if (td->td_flags & TDF_VERBOSE)
735 printf("kthread %p %s has exited\n", td, td->td_comm);
736 crit_enter();
737 lwkt_deschedule_self();
738 ++mycpu->gd_tdfreecount;
739 TAILQ_INSERT_TAIL(&mycpu->gd_tdfreeq, td, td_threadq);
740 cpu_thread_exit();
741}
742
743/*
744 * Create a kernel process/thread/whatever. It shares it's address space
ef0fdad1 745 * with proc0 - ie: kernel only. 5.x compatible.
99df837e
MD
746 */
747int
748kthread_create(void (*func)(void *), void *arg,
749 struct thread **tdp, const char *fmt, ...)
750{
751 struct thread *td;
752 va_list ap;
753
ef0fdad1 754 td = *tdp = lwkt_alloc_thread(NULL);
99df837e
MD
755 cpu_set_thread_handler(td, kthread_exit, func, arg);
756 td->td_flags |= TDF_VERBOSE;
757
758 /*
759 * Set up arg0 for 'ps' etc
760 */
761 va_start(ap, fmt);
762 vsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
763 va_end(ap);
764
765 /*
766 * Schedule the thread to run
767 */
768 lwkt_schedule(td);
769 return 0;
770}
771
772/*
773 * Destroy an LWKT thread. Warning! This function is not called when
774 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
775 * uses a different reaping mechanism.
776 *
777 * XXX duplicates lwkt_exit()
778 */
779void
780kthread_exit(void)
781{
782 lwkt_exit();
783}
784