ANSIfication and style cleanups. Non operational.
[dragonfly.git] / sys / kern / lwkt_thread.c
CommitLineData
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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 *
0a3f9b47 26 * $DragonFly: src/sys/kern/lwkt_thread.c,v 1.58 2004/03/30 19:14:11 dillon Exp $
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27 */
28
29/*
30 * Each cpu in a system has its own self-contained light weight kernel
31 * thread scheduler, which means that generally speaking we only need
32 * to use a critical section to avoid problems. Foreign thread
33 * scheduling is queued via (async) IPIs.
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34 */
35
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36#ifdef _KERNEL
37
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38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/kernel.h>
41#include <sys/proc.h>
42#include <sys/rtprio.h>
43#include <sys/queue.h>
f1d1c3fa 44#include <sys/thread2.h>
7d0bac62 45#include <sys/sysctl.h>
99df837e 46#include <sys/kthread.h>
f1d1c3fa 47#include <machine/cpu.h>
99df837e 48#include <sys/lock.h>
f6bf3af1 49#include <sys/caps.h>
f1d1c3fa 50
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51#include <vm/vm.h>
52#include <vm/vm_param.h>
53#include <vm/vm_kern.h>
54#include <vm/vm_object.h>
55#include <vm/vm_page.h>
56#include <vm/vm_map.h>
57#include <vm/vm_pager.h>
58#include <vm/vm_extern.h>
59#include <vm/vm_zone.h>
60
99df837e 61#include <machine/stdarg.h>
57c254db 62#include <machine/ipl.h>
96728c05 63#include <machine/smp.h>
99df837e 64
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65#define THREAD_STACK (UPAGES * PAGE_SIZE)
66
67#else
68
69#include <sys/stdint.h>
fb04f4fd 70#include <libcaps/thread.h>
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71#include <sys/thread.h>
72#include <sys/msgport.h>
73#include <sys/errno.h>
fb04f4fd 74#include <libcaps/globaldata.h>
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75#include <sys/thread2.h>
76#include <sys/msgport2.h>
709799ea 77#include <stdio.h>
05220613 78#include <stdlib.h>
709799ea 79#include <string.h>
c95cd171 80#include <machine/cpufunc.h>
709799ea 81#include <machine/lock.h>
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82
83#endif
84
7d0bac62 85static int untimely_switch = 0;
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86#ifdef INVARIANTS
87static int panic_on_cscount = 0;
88#endif
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89static __int64_t switch_count = 0;
90static __int64_t preempt_hit = 0;
91static __int64_t preempt_miss = 0;
92static __int64_t preempt_weird = 0;
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93
94#ifdef _KERNEL
95
96SYSCTL_INT(_lwkt, OID_AUTO, untimely_switch, CTLFLAG_RW, &untimely_switch, 0, "");
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97#ifdef INVARIANTS
98SYSCTL_INT(_lwkt, OID_AUTO, panic_on_cscount, CTLFLAG_RW, &panic_on_cscount, 0, "");
99#endif
4b5f931b 100SYSCTL_QUAD(_lwkt, OID_AUTO, switch_count, CTLFLAG_RW, &switch_count, 0, "");
4b5f931b 101SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_hit, CTLFLAG_RW, &preempt_hit, 0, "");
4b5f931b 102SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_miss, CTLFLAG_RW, &preempt_miss, 0, "");
26a0694b 103SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_weird, CTLFLAG_RW, &preempt_weird, 0, "");
7d0bac62 104
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105#endif
106
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107/*
108 * These helper procedures handle the runq, they can only be called from
109 * within a critical section.
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110 *
111 * WARNING! Prior to SMP being brought up it is possible to enqueue and
112 * dequeue threads belonging to other cpus, so be sure to use td->td_gd
113 * instead of 'mycpu' when referencing the globaldata structure. Once
114 * SMP live enqueuing and dequeueing only occurs on the current cpu.
4b5f931b 115 */
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116static __inline
117void
118_lwkt_dequeue(thread_t td)
119{
120 if (td->td_flags & TDF_RUNQ) {
4b5f931b 121 int nq = td->td_pri & TDPRI_MASK;
75cdbe6c 122 struct globaldata *gd = td->td_gd;
4b5f931b 123
f1d1c3fa 124 td->td_flags &= ~TDF_RUNQ;
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125 TAILQ_REMOVE(&gd->gd_tdrunq[nq], td, td_threadq);
126 /* runqmask is passively cleaned up by the switcher */
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127 }
128}
129
130static __inline
131void
132_lwkt_enqueue(thread_t td)
133{
134 if ((td->td_flags & TDF_RUNQ) == 0) {
4b5f931b 135 int nq = td->td_pri & TDPRI_MASK;
75cdbe6c 136 struct globaldata *gd = td->td_gd;
4b5f931b 137
f1d1c3fa 138 td->td_flags |= TDF_RUNQ;
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139 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], td, td_threadq);
140 gd->gd_runqmask |= 1 << nq;
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141 }
142}
8ad65e08 143
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144#ifdef _KERNEL
145
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146/*
147 * LWKTs operate on a per-cpu basis
148 *
73e4f7b9 149 * WARNING! Called from early boot, 'mycpu' may not work yet.
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150 */
151void
152lwkt_gdinit(struct globaldata *gd)
153{
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154 int i;
155
156 for (i = 0; i < sizeof(gd->gd_tdrunq)/sizeof(gd->gd_tdrunq[0]); ++i)
157 TAILQ_INIT(&gd->gd_tdrunq[i]);
158 gd->gd_runqmask = 0;
73e4f7b9 159 TAILQ_INIT(&gd->gd_tdallq);
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160}
161
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162#endif /* _KERNEL */
163
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164/*
165 * Initialize a thread wait structure prior to first use.
166 *
167 * NOTE! called from low level boot code, we cannot do anything fancy!
168 */
169void
41a01a4d 170lwkt_wait_init(lwkt_wait_t w)
7d0bac62 171{
41a01a4d 172 lwkt_token_init(&w->wa_token);
7d0bac62 173 TAILQ_INIT(&w->wa_waitq);
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174 w->wa_gen = 0;
175 w->wa_count = 0;
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176}
177
178/*
179 * Create a new thread. The thread must be associated with a process context
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180 * or LWKT start address before it can be scheduled. If the target cpu is
181 * -1 the thread will be created on the current cpu.
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182 *
183 * If you intend to create a thread without a process context this function
184 * does everything except load the startup and switcher function.
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185 */
186thread_t
75cdbe6c 187lwkt_alloc_thread(struct thread *td, int cpu)
7d0bac62 188{
99df837e 189 void *stack;
ef0fdad1 190 int flags = 0;
7d0bac62 191
ef0fdad1 192 if (td == NULL) {
26a0694b 193 crit_enter();
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194 if (mycpu->gd_tdfreecount > 0) {
195 --mycpu->gd_tdfreecount;
196 td = TAILQ_FIRST(&mycpu->gd_tdfreeq);
d9eea1a5 197 KASSERT(td != NULL && (td->td_flags & TDF_RUNNING) == 0,
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198 ("lwkt_alloc_thread: unexpected NULL or corrupted td"));
199 TAILQ_REMOVE(&mycpu->gd_tdfreeq, td, td_threadq);
200 crit_exit();
201 stack = td->td_kstack;
202 flags = td->td_flags & (TDF_ALLOCATED_STACK|TDF_ALLOCATED_THREAD);
203 } else {
204 crit_exit();
05220613 205#ifdef _KERNEL
ef0fdad1 206 td = zalloc(thread_zone);
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207#else
208 td = malloc(sizeof(struct thread));
209#endif
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210 td->td_kstack = NULL;
211 flags |= TDF_ALLOCATED_THREAD;
212 }
213 }
214 if ((stack = td->td_kstack) == NULL) {
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215#ifdef _KERNEL
216 stack = (void *)kmem_alloc(kernel_map, THREAD_STACK);
217#else
fb04f4fd 218 stack = libcaps_alloc_stack(THREAD_STACK);
05220613 219#endif
ef0fdad1 220 flags |= TDF_ALLOCATED_STACK;
99df837e 221 }
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222 if (cpu < 0)
223 lwkt_init_thread(td, stack, flags, mycpu);
224 else
225 lwkt_init_thread(td, stack, flags, globaldata_find(cpu));
99df837e 226 return(td);
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227}
228
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229#ifdef _KERNEL
230
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231/*
232 * Initialize a preexisting thread structure. This function is used by
233 * lwkt_alloc_thread() and also used to initialize the per-cpu idlethread.
234 *
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235 * All threads start out in a critical section at a priority of
236 * TDPRI_KERN_DAEMON. Higher level code will modify the priority as
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237 * appropriate. This function may send an IPI message when the
238 * requested cpu is not the current cpu and consequently gd_tdallq may
239 * not be initialized synchronously from the point of view of the originating
240 * cpu.
241 *
242 * NOTE! we have to be careful in regards to creating threads for other cpus
243 * if SMP has not yet been activated.
7d0bac62 244 */
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245#ifdef SMP
246
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247static void
248lwkt_init_thread_remote(void *arg)
249{
250 thread_t td = arg;
251
252 TAILQ_INSERT_TAIL(&td->td_gd->gd_tdallq, td, td_allq);
253}
254
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255#endif
256
7d0bac62 257void
26a0694b 258lwkt_init_thread(thread_t td, void *stack, int flags, struct globaldata *gd)
7d0bac62 259{
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260 bzero(td, sizeof(struct thread));
261 td->td_kstack = stack;
262 td->td_flags |= flags;
26a0694b 263 td->td_gd = gd;
f8c3996b 264 td->td_pri = TDPRI_KERN_DAEMON + TDPRI_CRIT;
c95cd171 265 lwkt_initport(&td->td_msgport, td);
99df837e 266 pmap_init_thread(td);
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267#ifdef SMP
268 if (gd == mycpu) {
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269 crit_enter();
270 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
271 crit_exit();
272 } else {
2db3b277 273 lwkt_send_ipiq(gd, lwkt_init_thread_remote, td);
75cdbe6c 274 }
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275#else
276 crit_enter();
277 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
278 crit_exit();
279#endif
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280}
281
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282#endif /* _KERNEL */
283
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284void
285lwkt_set_comm(thread_t td, const char *ctl, ...)
286{
e2565a42 287 __va_list va;
73e4f7b9 288
e2565a42 289 __va_start(va, ctl);
73e4f7b9 290 vsnprintf(td->td_comm, sizeof(td->td_comm), ctl, va);
e2565a42 291 __va_end(va);
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292}
293
99df837e 294void
73e4f7b9 295lwkt_hold(thread_t td)
99df837e 296{
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297 ++td->td_refs;
298}
299
300void
301lwkt_rele(thread_t td)
302{
303 KKASSERT(td->td_refs > 0);
304 --td->td_refs;
305}
306
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307#ifdef _KERNEL
308
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309void
310lwkt_wait_free(thread_t td)
311{
312 while (td->td_refs)
377d4740 313 tsleep(td, 0, "tdreap", hz);
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314}
315
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316#endif
317
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318void
319lwkt_free_thread(thread_t td)
320{
321 struct globaldata *gd = mycpu;
322
d9eea1a5 323 KASSERT((td->td_flags & TDF_RUNNING) == 0,
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324 ("lwkt_free_thread: did not exit! %p", td));
325
326 crit_enter();
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327 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq);
328 if (gd->gd_tdfreecount < CACHE_NTHREADS &&
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329 (td->td_flags & TDF_ALLOCATED_THREAD)
330 ) {
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331 ++gd->gd_tdfreecount;
332 TAILQ_INSERT_HEAD(&gd->gd_tdfreeq, td, td_threadq);
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333 crit_exit();
334 } else {
335 crit_exit();
336 if (td->td_kstack && (td->td_flags & TDF_ALLOCATED_STACK)) {
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337#ifdef _KERNEL
338 kmem_free(kernel_map, (vm_offset_t)td->td_kstack, THREAD_STACK);
339#else
fb04f4fd 340 libcaps_free_stack(td->td_kstack, THREAD_STACK);
05220613 341#endif
73e4f7b9 342 /* gd invalid */
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343 td->td_kstack = NULL;
344 }
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345 if (td->td_flags & TDF_ALLOCATED_THREAD) {
346#ifdef _KERNEL
99df837e 347 zfree(thread_zone, td);
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348#else
349 free(td);
350#endif
351 }
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352 }
353}
354
355
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356/*
357 * Switch to the next runnable lwkt. If no LWKTs are runnable then
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358 * switch to the idlethread. Switching must occur within a critical
359 * section to avoid races with the scheduling queue.
360 *
361 * We always have full control over our cpu's run queue. Other cpus
362 * that wish to manipulate our queue must use the cpu_*msg() calls to
363 * talk to our cpu, so a critical section is all that is needed and
364 * the result is very, very fast thread switching.
365 *
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366 * The LWKT scheduler uses a fixed priority model and round-robins at
367 * each priority level. User process scheduling is a totally
368 * different beast and LWKT priorities should not be confused with
369 * user process priorities.
f1d1c3fa 370 *
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371 * The MP lock may be out of sync with the thread's td_mpcount. lwkt_switch()
372 * cleans it up. Note that the td_switch() function cannot do anything that
373 * requires the MP lock since the MP lock will have already been setup for
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374 * the target thread (not the current thread). It's nice to have a scheduler
375 * that does not need the MP lock to work because it allows us to do some
376 * really cool high-performance MP lock optimizations.
8ad65e08 377 */
96728c05 378
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379void
380lwkt_switch(void)
381{
41a01a4d 382 globaldata_t gd;
f1d1c3fa 383 thread_t td = curthread;
8ad65e08 384 thread_t ntd;
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385#ifdef SMP
386 int mpheld;
387#endif
8ad65e08 388
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389 /*
390 * Switching from within a 'fast' (non thread switched) interrupt is
391 * illegal.
392 */
393 if (mycpu->gd_intr_nesting_level && panicstr == NULL) {
03aa8d99 394 panic("lwkt_switch: cannot switch from within a fast interrupt, yet\n");
96728c05 395 }
ef0fdad1 396
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397 /*
398 * Passive release (used to transition from user to kernel mode
399 * when we block or switch rather then when we enter the kernel).
400 * This function is NOT called if we are switching into a preemption
401 * or returning from a preemption. Typically this causes us to lose
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402 * our current process designation (if we have one) and become a true
403 * LWKT thread, and may also hand the current process designation to
404 * another process and schedule thread.
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405 */
406 if (td->td_release)
407 td->td_release(td);
408
f1d1c3fa 409 crit_enter();
4b5f931b 410 ++switch_count;
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411
412#ifdef SMP
413 /*
414 * td_mpcount cannot be used to determine if we currently hold the
415 * MP lock because get_mplock() will increment it prior to attempting
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416 * to get the lock, and switch out if it can't. Our ownership of
417 * the actual lock will remain stable while we are in a critical section
418 * (but, of course, another cpu may own or release the lock so the
419 * actual value of mp_lock is not stable).
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420 */
421 mpheld = MP_LOCK_HELD();
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422#ifdef INVARIANTS
423 if (td->td_cscount) {
424 printf("Diagnostic: attempt to switch while mastering cpusync: %p\n",
425 td);
426 if (panic_on_cscount)
427 panic("switching while mastering cpusync");
428 }
429#endif
8a8d5d85 430#endif
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431 if ((ntd = td->td_preempted) != NULL) {
432 /*
433 * We had preempted another thread on this cpu, resume the preempted
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434 * thread. This occurs transparently, whether the preempted thread
435 * was scheduled or not (it may have been preempted after descheduling
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436 * itself).
437 *
438 * We have to setup the MP lock for the original thread after backing
439 * out the adjustment that was made to curthread when the original
440 * was preempted.
99df837e 441 */
26a0694b 442 KKASSERT(ntd->td_flags & TDF_PREEMPT_LOCK);
8a8d5d85 443#ifdef SMP
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444 if (ntd->td_mpcount && mpheld == 0) {
445 panic("MPLOCK NOT HELD ON RETURN: %p %p %d %d\n",
446 td, ntd, td->td_mpcount, ntd->td_mpcount);
447 }
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448 if (ntd->td_mpcount) {
449 td->td_mpcount -= ntd->td_mpcount;
450 KKASSERT(td->td_mpcount >= 0);
451 }
452#endif
26a0694b 453 ntd->td_flags |= TDF_PREEMPT_DONE;
8a8d5d85 454 /* YYY release mp lock on switchback if original doesn't need it */
8ad65e08 455 } else {
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456 /*
457 * Priority queue / round-robin at each priority. Note that user
458 * processes run at a fixed, low priority and the user process
459 * scheduler deals with interactions between user processes
460 * by scheduling and descheduling them from the LWKT queue as
461 * necessary.
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462 *
463 * We have to adjust the MP lock for the target thread. If we
464 * need the MP lock and cannot obtain it we try to locate a
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465 * thread that does not need the MP lock. If we cannot, we spin
466 * instead of HLT.
467 *
468 * A similar issue exists for the tokens held by the target thread.
469 * If we cannot obtain ownership of the tokens we cannot immediately
470 * schedule the thread.
471 */
472
473 /*
474 * We are switching threads. If there are any pending requests for
475 * tokens we can satisfy all of them here.
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476 */
477 gd = mycpu;
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478#ifdef SMP
479 if (gd->gd_tokreqbase)
480 lwkt_drain_token_requests();
481#endif
482
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483again:
484 if (gd->gd_runqmask) {
485 int nq = bsrl(gd->gd_runqmask);
486 if ((ntd = TAILQ_FIRST(&gd->gd_tdrunq[nq])) == NULL) {
487 gd->gd_runqmask &= ~(1 << nq);
488 goto again;
489 }
8a8d5d85 490#ifdef SMP
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491 /*
492 * If the target needs the MP lock and we couldn't get it,
493 * or if the target is holding tokens and we could not
494 * gain ownership of the tokens, continue looking for a
495 * thread to schedule and spin instead of HLT if we can't.
496 */
497 if ((ntd->td_mpcount && mpheld == 0 && !cpu_try_mplock()) ||
498 (ntd->td_toks && lwkt_chktokens(ntd) == 0)
499 ) {
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500 u_int32_t rqmask = gd->gd_runqmask;
501 while (rqmask) {
502 TAILQ_FOREACH(ntd, &gd->gd_tdrunq[nq], td_threadq) {
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503 if (ntd->td_mpcount && !mpheld && !cpu_try_mplock())
504 continue;
505 mpheld = MP_LOCK_HELD();
506 if (ntd->td_toks && !lwkt_chktokens(ntd))
507 continue;
508 break;
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509 }
510 if (ntd)
511 break;
512 rqmask &= ~(1 << nq);
513 nq = bsrl(rqmask);
514 }
515 if (ntd == NULL) {
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516 ntd = &gd->gd_idlethread;
517 ntd->td_flags |= TDF_IDLE_NOHLT;
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518 } else {
519 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
520 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
521 }
522 } else {
523 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
524 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
525 }
526#else
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527 TAILQ_REMOVE(&gd->gd_tdrunq[nq], ntd, td_threadq);
528 TAILQ_INSERT_TAIL(&gd->gd_tdrunq[nq], ntd, td_threadq);
8a8d5d85 529#endif
4b5f931b 530 } else {
3c23a41a 531 /*
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532 * We have nothing to run but only let the idle loop halt
533 * the cpu if there are no pending interrupts.
3c23a41a 534 */
a2a5ad0d 535 ntd = &gd->gd_idlethread;
60f945af 536 if (gd->gd_reqflags & RQF_IDLECHECK_MASK)
3c23a41a 537 ntd->td_flags |= TDF_IDLE_NOHLT;
4b5f931b 538 }
f1d1c3fa 539 }
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540 KASSERT(ntd->td_pri >= TDPRI_CRIT,
541 ("priority problem in lwkt_switch %d %d", td->td_pri, ntd->td_pri));
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542
543 /*
544 * Do the actual switch. If the new target does not need the MP lock
545 * and we are holding it, release the MP lock. If the new target requires
546 * the MP lock we have already acquired it for the target.
547 */
548#ifdef SMP
549 if (ntd->td_mpcount == 0 ) {
550 if (MP_LOCK_HELD())
551 cpu_rel_mplock();
552 } else {
553 ASSERT_MP_LOCK_HELD();
554 }
555#endif
8a8d5d85 556 if (td != ntd) {
f1d1c3fa 557 td->td_switch(ntd);
8a8d5d85 558 }
96728c05 559
f1d1c3fa 560 crit_exit();
8ad65e08
MD
561}
562
b68b7282 563/*
96728c05
MD
564 * Request that the target thread preempt the current thread. Preemption
565 * only works under a specific set of conditions:
b68b7282 566 *
96728c05
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567 * - We are not preempting ourselves
568 * - The target thread is owned by the current cpu
569 * - We are not currently being preempted
570 * - The target is not currently being preempted
571 * - We are able to satisfy the target's MP lock requirements (if any).
572 *
573 * THE CALLER OF LWKT_PREEMPT() MUST BE IN A CRITICAL SECTION. Typically
574 * this is called via lwkt_schedule() through the td_preemptable callback.
575 * critpri is the managed critical priority that we should ignore in order
576 * to determine whether preemption is possible (aka usually just the crit
577 * priority of lwkt_schedule() itself).
b68b7282 578 *
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MD
579 * XXX at the moment we run the target thread in a critical section during
580 * the preemption in order to prevent the target from taking interrupts
581 * that *WE* can't. Preemption is strictly limited to interrupt threads
582 * and interrupt-like threads, outside of a critical section, and the
583 * preempted source thread will be resumed the instant the target blocks
584 * whether or not the source is scheduled (i.e. preemption is supposed to
585 * be as transparent as possible).
4b5f931b 586 *
8a8d5d85
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587 * The target thread inherits our MP count (added to its own) for the
588 * duration of the preemption in order to preserve the atomicy of the
96728c05
MD
589 * MP lock during the preemption. Therefore, any preempting targets must be
590 * careful in regards to MP assertions. Note that the MP count may be
71ef2f5c
MD
591 * out of sync with the physical mp_lock, but we do not have to preserve
592 * the original ownership of the lock if it was out of synch (that is, we
593 * can leave it synchronized on return).
b68b7282
MD
594 */
595void
96728c05 596lwkt_preempt(thread_t ntd, int critpri)
b68b7282 597{
46a3f46d 598 struct globaldata *gd = mycpu;
0a3f9b47 599 thread_t td;
8a8d5d85
MD
600#ifdef SMP
601 int mpheld;
57c254db 602 int savecnt;
8a8d5d85 603#endif
b68b7282 604
26a0694b 605 /*
96728c05
MD
606 * The caller has put us in a critical section. We can only preempt
607 * if the caller of the caller was not in a critical section (basically
0a3f9b47 608 * a local interrupt), as determined by the 'critpri' parameter.
96728c05
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609 *
610 * YYY The target thread must be in a critical section (else it must
611 * inherit our critical section? I dunno yet).
41a01a4d
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612 *
613 * Any tokens held by the target may not be held by thread(s) being
614 * preempted. We take the easy way out and do not preempt if
615 * the target is holding tokens.
0a3f9b47
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616 *
617 * Set need_lwkt_resched() unconditionally for now YYY.
26a0694b
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618 */
619 KASSERT(ntd->td_pri >= TDPRI_CRIT, ("BADCRIT0 %d", ntd->td_pri));
26a0694b 620
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621 td = gd->gd_curthread;
622 need_lwkt_resched();
623 if ((ntd->td_pri & TDPRI_MASK) <= (td->td_pri & TDPRI_MASK)) {
57c254db
MD
624 ++preempt_miss;
625 return;
626 }
96728c05
MD
627 if ((td->td_pri & ~TDPRI_MASK) > critpri) {
628 ++preempt_miss;
629 return;
630 }
631#ifdef SMP
46a3f46d 632 if (ntd->td_gd != gd) {
96728c05
MD
633 ++preempt_miss;
634 return;
635 }
636#endif
41a01a4d
MD
637 /*
638 * Take the easy way out and do not preempt if the target is holding
639 * one or more tokens. We could test whether the thread(s) being
640 * preempted interlock against the target thread's tokens and whether
641 * we can get all the target thread's tokens, but this situation
642 * should not occur very often so its easier to simply not preempt.
643 */
644 if (ntd->td_toks != NULL) {
645 ++preempt_miss;
646 return;
647 }
26a0694b
MD
648 if (td == ntd || ((td->td_flags | ntd->td_flags) & TDF_PREEMPT_LOCK)) {
649 ++preempt_weird;
650 return;
651 }
652 if (ntd->td_preempted) {
4b5f931b 653 ++preempt_hit;
26a0694b 654 return;
b68b7282 655 }
8a8d5d85 656#ifdef SMP
a2a5ad0d
MD
657 /*
658 * note: an interrupt might have occured just as we were transitioning
71ef2f5c
MD
659 * to or from the MP lock. In this case td_mpcount will be pre-disposed
660 * (non-zero) but not actually synchronized with the actual state of the
661 * lock. We can use it to imply an MP lock requirement for the
662 * preemption but we cannot use it to test whether we hold the MP lock
663 * or not.
a2a5ad0d 664 */
96728c05 665 savecnt = td->td_mpcount;
71ef2f5c 666 mpheld = MP_LOCK_HELD();
8a8d5d85
MD
667 ntd->td_mpcount += td->td_mpcount;
668 if (mpheld == 0 && ntd->td_mpcount && !cpu_try_mplock()) {
669 ntd->td_mpcount -= td->td_mpcount;
670 ++preempt_miss;
671 return;
672 }
673#endif
26a0694b
MD
674
675 ++preempt_hit;
676 ntd->td_preempted = td;
677 td->td_flags |= TDF_PREEMPT_LOCK;
678 td->td_switch(ntd);
679 KKASSERT(ntd->td_preempted && (td->td_flags & TDF_PREEMPT_DONE));
96728c05
MD
680#ifdef SMP
681 KKASSERT(savecnt == td->td_mpcount);
71ef2f5c
MD
682 mpheld = MP_LOCK_HELD();
683 if (mpheld && td->td_mpcount == 0)
96728c05 684 cpu_rel_mplock();
71ef2f5c 685 else if (mpheld == 0 && td->td_mpcount)
96728c05
MD
686 panic("lwkt_preempt(): MP lock was not held through");
687#endif
26a0694b
MD
688 ntd->td_preempted = NULL;
689 td->td_flags &= ~(TDF_PREEMPT_LOCK|TDF_PREEMPT_DONE);
b68b7282
MD
690}
691
f1d1c3fa
MD
692/*
693 * Yield our thread while higher priority threads are pending. This is
694 * typically called when we leave a critical section but it can be safely
695 * called while we are in a critical section.
696 *
697 * This function will not generally yield to equal priority threads but it
698 * can occur as a side effect. Note that lwkt_switch() is called from
46a3f46d 699 * inside the critical section to prevent its own crit_exit() from reentering
f1d1c3fa
MD
700 * lwkt_yield_quick().
701 *
235957ed 702 * gd_reqflags indicates that *something* changed, e.g. an interrupt or softint
ef0fdad1
MD
703 * came along but was blocked and made pending.
704 *
f1d1c3fa
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705 * (self contained on a per cpu basis)
706 */
707void
708lwkt_yield_quick(void)
709{
7966cb69
MD
710 globaldata_t gd = mycpu;
711 thread_t td = gd->gd_curthread;
ef0fdad1 712
a2a5ad0d 713 /*
235957ed 714 * gd_reqflags is cleared in splz if the cpl is 0. If we were to clear
a2a5ad0d
MD
715 * it with a non-zero cpl then we might not wind up calling splz after
716 * a task switch when the critical section is exited even though the
46a3f46d 717 * new task could accept the interrupt.
a2a5ad0d
MD
718 *
719 * XXX from crit_exit() only called after last crit section is released.
720 * If called directly will run splz() even if in a critical section.
46a3f46d
MD
721 *
722 * td_nest_count prevent deep nesting via splz() or doreti(). Note that
723 * except for this special case, we MUST call splz() here to handle any
724 * pending ints, particularly after we switch, or we might accidently
725 * halt the cpu with interrupts pending.
a2a5ad0d 726 */
46a3f46d 727 if (gd->gd_reqflags && td->td_nest_count < 2)
f1d1c3fa 728 splz();
f1d1c3fa
MD
729
730 /*
731 * YYY enabling will cause wakeup() to task-switch, which really
732 * confused the old 4.x code. This is a good way to simulate
7d0bac62
MD
733 * preemption and MP without actually doing preemption or MP, because a
734 * lot of code assumes that wakeup() does not block.
f1d1c3fa 735 */
46a3f46d
MD
736 if (untimely_switch && td->td_nest_count == 0 &&
737 gd->gd_intr_nesting_level == 0
738 ) {
f1d1c3fa
MD
739 crit_enter();
740 /*
741 * YYY temporary hacks until we disassociate the userland scheduler
742 * from the LWKT scheduler.
743 */
744 if (td->td_flags & TDF_RUNQ) {
745 lwkt_switch(); /* will not reenter yield function */
746 } else {
747 lwkt_schedule_self(); /* make sure we are scheduled */
748 lwkt_switch(); /* will not reenter yield function */
749 lwkt_deschedule_self(); /* make sure we are descheduled */
750 }
7966cb69 751 crit_exit_noyield(td);
f1d1c3fa 752 }
f1d1c3fa
MD
753}
754
8ad65e08 755/*
f1d1c3fa 756 * This implements a normal yield which, unlike _quick, will yield to equal
235957ed 757 * priority threads as well. Note that gd_reqflags tests will be handled by
f1d1c3fa
MD
758 * the crit_exit() call in lwkt_switch().
759 *
760 * (self contained on a per cpu basis)
8ad65e08
MD
761 */
762void
f1d1c3fa 763lwkt_yield(void)
8ad65e08 764{
f1d1c3fa
MD
765 lwkt_schedule_self();
766 lwkt_switch();
767}
768
769/*
770 * Schedule a thread to run. As the current thread we can always safely
771 * schedule ourselves, and a shortcut procedure is provided for that
772 * function.
773 *
774 * (non-blocking, self contained on a per cpu basis)
775 */
776void
777lwkt_schedule_self(void)
778{
779 thread_t td = curthread;
780
41a01a4d 781 crit_enter_quick(td);
f1d1c3fa 782 KASSERT(td->td_wait == NULL, ("lwkt_schedule_self(): td_wait not NULL!"));
41a01a4d 783 KASSERT(td != &td->td_gd->gd_idlethread, ("lwkt_schedule_self(): scheduling gd_idlethread is illegal!"));
f1d1c3fa 784 _lwkt_enqueue(td);
05220613 785#ifdef _KERNEL
26a0694b
MD
786 if (td->td_proc && td->td_proc->p_stat == SSLEEP)
787 panic("SCHED SELF PANIC");
05220613 788#endif
41a01a4d 789 crit_exit_quick(td);
8ad65e08 790}
8ad65e08
MD
791
792/*
f1d1c3fa
MD
793 * Generic schedule. Possibly schedule threads belonging to other cpus and
794 * deal with threads that might be blocked on a wait queue.
795 *
0a3f9b47
MD
796 * We have a little helper inline function which does additional work after
797 * the thread has been enqueued, including dealing with preemption and
798 * setting need_lwkt_resched() (which prevents the kernel from returning
799 * to userland until it has processed higher priority threads).
8ad65e08 800 */
0a3f9b47
MD
801static __inline
802void
803_lwkt_schedule_post(thread_t ntd, int cpri)
804{
805 if (ntd->td_preemptable) {
806 ntd->td_preemptable(ntd, cpri); /* YYY +token */
807 } else {
808 if ((ntd->td_flags & TDF_NORESCHED) == 0) {
809 if ((ntd->td_pri & TDPRI_MASK) >= TDPRI_KERN_USER)
810 need_lwkt_resched();
811 }
812 }
813}
814
8ad65e08
MD
815void
816lwkt_schedule(thread_t td)
817{
96728c05 818#ifdef INVARIANTS
41a01a4d 819 KASSERT(td != &td->td_gd->gd_idlethread, ("lwkt_schedule(): scheduling gd_idlethread is illegal!"));
26a0694b
MD
820 if ((td->td_flags & TDF_PREEMPT_LOCK) == 0 && td->td_proc
821 && td->td_proc->p_stat == SSLEEP
822 ) {
823 printf("PANIC schedule curtd = %p (%d %d) target %p (%d %d)\n",
824 curthread,
825 curthread->td_proc ? curthread->td_proc->p_pid : -1,
826 curthread->td_proc ? curthread->td_proc->p_stat : -1,
827 td,
828 td->td_proc ? curthread->td_proc->p_pid : -1,
829 td->td_proc ? curthread->td_proc->p_stat : -1
830 );
831 panic("SCHED PANIC");
832 }
96728c05 833#endif
f1d1c3fa
MD
834 crit_enter();
835 if (td == curthread) {
836 _lwkt_enqueue(td);
837 } else {
838 lwkt_wait_t w;
839
840 /*
841 * If the thread is on a wait list we have to send our scheduling
842 * request to the owner of the wait structure. Otherwise we send
843 * the scheduling request to the cpu owning the thread. Races
844 * are ok, the target will forward the message as necessary (the
845 * message may chase the thread around before it finally gets
846 * acted upon).
847 *
848 * (remember, wait structures use stable storage)
0a3f9b47
MD
849 *
850 * NOTE: tokens no longer enter a critical section, so we only need
851 * to account for the crit_enter() above when calling
852 * _lwkt_schedule_post().
f1d1c3fa
MD
853 */
854 if ((w = td->td_wait) != NULL) {
41a01a4d
MD
855 lwkt_tokref wref;
856
857 if (lwkt_trytoken(&wref, &w->wa_token)) {
f1d1c3fa
MD
858 TAILQ_REMOVE(&w->wa_waitq, td, td_threadq);
859 --w->wa_count;
860 td->td_wait = NULL;
0f7a3396
MD
861#ifdef SMP
862 if (td->td_gd == mycpu) {
f1d1c3fa 863 _lwkt_enqueue(td);
0a3f9b47 864 _lwkt_schedule_post(td, TDPRI_CRIT);
f1d1c3fa 865 } else {
2db3b277 866 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa 867 }
0f7a3396
MD
868#else
869 _lwkt_enqueue(td);
0a3f9b47 870 _lwkt_schedule_post(td, TDPRI_CRIT);
0f7a3396 871#endif
41a01a4d 872 lwkt_reltoken(&wref);
f1d1c3fa 873 } else {
96728c05 874 lwkt_send_ipiq(w->wa_token.t_cpu, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa
MD
875 }
876 } else {
877 /*
878 * If the wait structure is NULL and we own the thread, there
879 * is no race (since we are in a critical section). If we
880 * do not own the thread there might be a race but the
881 * target cpu will deal with it.
882 */
0f7a3396
MD
883#ifdef SMP
884 if (td->td_gd == mycpu) {
f1d1c3fa 885 _lwkt_enqueue(td);
0a3f9b47 886 _lwkt_schedule_post(td, TDPRI_CRIT);
f1d1c3fa 887 } else {
2db3b277 888 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa 889 }
0f7a3396
MD
890#else
891 _lwkt_enqueue(td);
0a3f9b47 892 _lwkt_schedule_post(td, TDPRI_CRIT);
0f7a3396 893#endif
f1d1c3fa 894 }
8ad65e08 895 }
f1d1c3fa 896 crit_exit();
8ad65e08
MD
897}
898
d9eea1a5
MD
899/*
900 * Managed acquisition. This code assumes that the MP lock is held for
901 * the tdallq operation and that the thread has been descheduled from its
902 * original cpu. We also have to wait for the thread to be entirely switched
903 * out on its original cpu (this is usually fast enough that we never loop)
904 * since the LWKT system does not have to hold the MP lock while switching
905 * and the target may have released it before switching.
906 */
a2a5ad0d
MD
907void
908lwkt_acquire(thread_t td)
909{
910 struct globaldata *gd;
911
912 gd = td->td_gd;
913 KKASSERT((td->td_flags & TDF_RUNQ) == 0);
d9eea1a5
MD
914 while (td->td_flags & TDF_RUNNING) /* XXX spin */
915 ;
a2a5ad0d
MD
916 if (gd != mycpu) {
917 crit_enter();
918 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq); /* protected by BGL */
919 gd = mycpu;
920 td->td_gd = gd;
a2a5ad0d
MD
921 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq); /* protected by BGL */
922 crit_exit();
923 }
924}
925
8ad65e08 926/*
f1d1c3fa
MD
927 * Deschedule a thread.
928 *
929 * (non-blocking, self contained on a per cpu basis)
930 */
931void
932lwkt_deschedule_self(void)
933{
934 thread_t td = curthread;
935
936 crit_enter();
937 KASSERT(td->td_wait == NULL, ("lwkt_schedule_self(): td_wait not NULL!"));
f1d1c3fa
MD
938 _lwkt_dequeue(td);
939 crit_exit();
940}
941
942/*
943 * Generic deschedule. Descheduling threads other then your own should be
944 * done only in carefully controlled circumstances. Descheduling is
945 * asynchronous.
946 *
947 * This function may block if the cpu has run out of messages.
8ad65e08
MD
948 */
949void
950lwkt_deschedule(thread_t td)
951{
f1d1c3fa
MD
952 crit_enter();
953 if (td == curthread) {
954 _lwkt_dequeue(td);
955 } else {
a72187e9 956 if (td->td_gd == mycpu) {
f1d1c3fa
MD
957 _lwkt_dequeue(td);
958 } else {
2db3b277 959 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_deschedule, td);
f1d1c3fa
MD
960 }
961 }
962 crit_exit();
963}
964
4b5f931b
MD
965/*
966 * Set the target thread's priority. This routine does not automatically
967 * switch to a higher priority thread, LWKT threads are not designed for
968 * continuous priority changes. Yield if you want to switch.
969 *
970 * We have to retain the critical section count which uses the high bits
26a0694b
MD
971 * of the td_pri field. The specified priority may also indicate zero or
972 * more critical sections by adding TDPRI_CRIT*N.
18bbe476
MD
973 *
974 * Note that we requeue the thread whether it winds up on a different runq
975 * or not. uio_yield() depends on this and the routine is not normally
976 * called with the same priority otherwise.
4b5f931b
MD
977 */
978void
979lwkt_setpri(thread_t td, int pri)
980{
26a0694b 981 KKASSERT(pri >= 0);
a72187e9 982 KKASSERT(td->td_gd == mycpu);
26a0694b
MD
983 crit_enter();
984 if (td->td_flags & TDF_RUNQ) {
985 _lwkt_dequeue(td);
986 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
987 _lwkt_enqueue(td);
988 } else {
989 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
990 }
991 crit_exit();
992}
993
994void
995lwkt_setpri_self(int pri)
996{
997 thread_t td = curthread;
998
4b5f931b
MD
999 KKASSERT(pri >= 0 && pri <= TDPRI_MAX);
1000 crit_enter();
1001 if (td->td_flags & TDF_RUNQ) {
1002 _lwkt_dequeue(td);
1003 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
1004 _lwkt_enqueue(td);
1005 } else {
1006 td->td_pri = (td->td_pri & ~TDPRI_MASK) + pri;
1007 }
1008 crit_exit();
1009}
1010
1011struct proc *
1012lwkt_preempted_proc(void)
1013{
73e4f7b9 1014 thread_t td = curthread;
4b5f931b
MD
1015 while (td->td_preempted)
1016 td = td->td_preempted;
1017 return(td->td_proc);
1018}
1019
f1d1c3fa 1020/*
41a01a4d
MD
1021 * Block on the specified wait queue until signaled. A generation number
1022 * must be supplied to interlock the wait queue. The function will
1023 * return immediately if the generation number does not match the wait
1024 * structure's generation number.
f1d1c3fa
MD
1025 */
1026void
ae8050a4 1027lwkt_block(lwkt_wait_t w, const char *wmesg, int *gen)
f1d1c3fa
MD
1028{
1029 thread_t td = curthread;
41a01a4d 1030 lwkt_tokref ilock;
f1d1c3fa 1031
41a01a4d
MD
1032 lwkt_gettoken(&ilock, &w->wa_token);
1033 crit_enter();
ae8050a4 1034 if (w->wa_gen == *gen) {
f1d1c3fa
MD
1035 _lwkt_dequeue(td);
1036 TAILQ_INSERT_TAIL(&w->wa_waitq, td, td_threadq);
1037 ++w->wa_count;
1038 td->td_wait = w;
ae8050a4 1039 td->td_wmesg = wmesg;
41a01a4d 1040 again:
f1d1c3fa 1041 lwkt_switch();
ece04fd0
MD
1042 if (td->td_wmesg != NULL) {
1043 _lwkt_dequeue(td);
1044 goto again;
1045 }
8ad65e08 1046 }
41a01a4d 1047 crit_exit();
ae8050a4 1048 *gen = w->wa_gen;
41a01a4d 1049 lwkt_reltoken(&ilock);
f1d1c3fa
MD
1050}
1051
1052/*
1053 * Signal a wait queue. We gain ownership of the wait queue in order to
1054 * signal it. Once a thread is removed from the wait queue we have to
1055 * deal with the cpu owning the thread.
1056 *
1057 * Note: alternatively we could message the target cpu owning the wait
1058 * queue. YYY implement as sysctl.
1059 */
1060void
ece04fd0 1061lwkt_signal(lwkt_wait_t w, int count)
f1d1c3fa
MD
1062{
1063 thread_t td;
41a01a4d 1064 lwkt_tokref ilock;
f1d1c3fa 1065
41a01a4d 1066 lwkt_gettoken(&ilock, &w->wa_token);
f1d1c3fa 1067 ++w->wa_gen;
41a01a4d 1068 crit_enter();
ece04fd0
MD
1069 if (count < 0)
1070 count = w->wa_count;
f1d1c3fa
MD
1071 while ((td = TAILQ_FIRST(&w->wa_waitq)) != NULL && count) {
1072 --count;
1073 --w->wa_count;
1074 TAILQ_REMOVE(&w->wa_waitq, td, td_threadq);
1075 td->td_wait = NULL;
ae8050a4 1076 td->td_wmesg = NULL;
a72187e9 1077 if (td->td_gd == mycpu) {
f1d1c3fa
MD
1078 _lwkt_enqueue(td);
1079 } else {
2db3b277 1080 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_schedule, td);
f1d1c3fa 1081 }
f1d1c3fa 1082 }
41a01a4d
MD
1083 crit_exit();
1084 lwkt_reltoken(&ilock);
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1085}
1086
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1087/*
1088 * Create a kernel process/thread/whatever. It shares it's address space
1089 * with proc0 - ie: kernel only.
1090 *
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1091 * NOTE! By default new threads are created with the MP lock held. A
1092 * thread which does not require the MP lock should release it by calling
1093 * rel_mplock() at the start of the new thread.
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1094 */
1095int
1096lwkt_create(void (*func)(void *), void *arg,
75cdbe6c 1097 struct thread **tdp, thread_t template, int tdflags, int cpu,
ef0fdad1 1098 const char *fmt, ...)
99df837e 1099{
73e4f7b9 1100 thread_t td;
e2565a42 1101 __va_list ap;
99df837e 1102
75cdbe6c 1103 td = lwkt_alloc_thread(template, cpu);
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1104 if (tdp)
1105 *tdp = td;
709799ea 1106 cpu_set_thread_handler(td, lwkt_exit, func, arg);
ef0fdad1 1107 td->td_flags |= TDF_VERBOSE | tdflags;
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1108#ifdef SMP
1109 td->td_mpcount = 1;
1110#endif
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1111
1112 /*
1113 * Set up arg0 for 'ps' etc
1114 */
e2565a42 1115 __va_start(ap, fmt);
99df837e 1116 vsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
e2565a42 1117 __va_end(ap);
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1118
1119 /*
1120 * Schedule the thread to run
1121 */
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1122 if ((td->td_flags & TDF_STOPREQ) == 0)
1123 lwkt_schedule(td);
1124 else
1125 td->td_flags &= ~TDF_STOPREQ;
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1126 return 0;
1127}
1128
2d93b37a 1129/*
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1130 * kthread_* is specific to the kernel and is not needed by userland.
1131 */
1132#ifdef _KERNEL
1133
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1134/*
1135 * Destroy an LWKT thread. Warning! This function is not called when
1136 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
1137 * uses a different reaping mechanism.
1138 */
1139void
1140lwkt_exit(void)
1141{
1142 thread_t td = curthread;
1143
1144 if (td->td_flags & TDF_VERBOSE)
1145 printf("kthread %p %s has exited\n", td, td->td_comm);
f6bf3af1 1146 caps_exit(td);
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1147 crit_enter();
1148 lwkt_deschedule_self();
1149 ++mycpu->gd_tdfreecount;
1150 TAILQ_INSERT_TAIL(&mycpu->gd_tdfreeq, td, td_threadq);
1151 cpu_thread_exit();
1152}
1153
1154/*
1155 * Create a kernel process/thread/whatever. It shares it's address space
ef0fdad1 1156 * with proc0 - ie: kernel only. 5.x compatible.
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1157 *
1158 * NOTE! By default kthreads are created with the MP lock held. A
1159 * thread which does not require the MP lock should release it by calling
1160 * rel_mplock() at the start of the new thread.
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1161 */
1162int
1163kthread_create(void (*func)(void *), void *arg,
1164 struct thread **tdp, const char *fmt, ...)
1165{
73e4f7b9 1166 thread_t td;
e2565a42 1167 __va_list ap;
99df837e 1168
75cdbe6c 1169 td = lwkt_alloc_thread(NULL, -1);
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1170 if (tdp)
1171 *tdp = td;
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1172 cpu_set_thread_handler(td, kthread_exit, func, arg);
1173 td->td_flags |= TDF_VERBOSE;
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1174#ifdef SMP
1175 td->td_mpcount = 1;
1176#endif
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1177
1178 /*
1179 * Set up arg0 for 'ps' etc
1180 */
e2565a42 1181 __va_start(ap, fmt);
99df837e 1182 vsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
e2565a42 1183 __va_end(ap);
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1184
1185 /*
1186 * Schedule the thread to run
1187 */
1188 lwkt_schedule(td);
1189 return 0;
1190}
1191
1192/*
1193 * Destroy an LWKT thread. Warning! This function is not called when
1194 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
1195 * uses a different reaping mechanism.
1196 *
1197 * XXX duplicates lwkt_exit()
1198 */
1199void
1200kthread_exit(void)
1201{
1202 lwkt_exit();
1203}
1204
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1205#endif /* _KERNEL */
1206
1207void
1208crit_panic(void)
1209{
1210 thread_t td = curthread;
1211 int lpri = td->td_pri;
1212
1213 td->td_pri = 0;
1214 panic("td_pri is/would-go negative! %p %d", td, lpri);
1215}
1216