kernel - Uninline crit_exit()
[dragonfly.git] / sys / kern / lwkt_thread.c
CommitLineData
8ad65e08 1/*
3b998fa9 2 * Copyright (c) 2003-2010 The DragonFly Project. All rights reserved.
60f60350 3 *
8c10bfcf
MD
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
60f60350 6 *
8ad65e08
MD
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
60f60350 10 *
8ad65e08
MD
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
8c10bfcf
MD
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.
60f60350 20 *
8c10bfcf
MD
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.
75cdbe6c
MD
33 */
34
35/*
36 * Each cpu in a system has its own self-contained light weight kernel
37 * thread scheduler, which means that generally speaking we only need
38 * to use a critical section to avoid problems. Foreign thread
39 * scheduling is queued via (async) IPIs.
8ad65e08
MD
40 */
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/kernel.h>
45#include <sys/proc.h>
46#include <sys/rtprio.h>
b37f18d6 47#include <sys/kinfo.h>
8ad65e08 48#include <sys/queue.h>
7d0bac62 49#include <sys/sysctl.h>
99df837e 50#include <sys/kthread.h>
f1d1c3fa 51#include <machine/cpu.h>
99df837e 52#include <sys/lock.h>
f6bf3af1 53#include <sys/caps.h>
9d265729 54#include <sys/spinlock.h>
57aa743c 55#include <sys/ktr.h>
9d265729
MD
56
57#include <sys/thread2.h>
58#include <sys/spinlock2.h>
684a93c4 59#include <sys/mplock2.h>
f1d1c3fa 60
8c72e3d5
AH
61#include <sys/dsched.h>
62
7d0bac62
MD
63#include <vm/vm.h>
64#include <vm/vm_param.h>
65#include <vm/vm_kern.h>
66#include <vm/vm_object.h>
67#include <vm/vm_page.h>
68#include <vm/vm_map.h>
69#include <vm/vm_pager.h>
70#include <vm/vm_extern.h>
7d0bac62 71
99df837e 72#include <machine/stdarg.h>
96728c05 73#include <machine/smp.h>
99df837e 74
d850923c
AE
75#if !defined(KTR_CTXSW)
76#define KTR_CTXSW KTR_ALL
77#endif
78KTR_INFO_MASTER(ctxsw);
a1f0fb66
AE
79KTR_INFO(KTR_CTXSW, ctxsw, sw, 0, "#cpu[%d].td = %p",
80 sizeof(int) + sizeof(struct thread *));
81KTR_INFO(KTR_CTXSW, ctxsw, pre, 1, "#cpu[%d].td = %p",
82 sizeof(int) + sizeof(struct thread *));
83KTR_INFO(KTR_CTXSW, ctxsw, newtd, 2, "#threads[%p].name = %s",
84 sizeof (struct thread *) + sizeof(char *));
85KTR_INFO(KTR_CTXSW, ctxsw, deadtd, 3, "#threads[%p].name = <dead>", sizeof (struct thread *));
1541028a 86
40aaf5fc
NT
87static MALLOC_DEFINE(M_THREAD, "thread", "lwkt threads");
88
0f7a3396
MD
89#ifdef INVARIANTS
90static int panic_on_cscount = 0;
91#endif
05220613
MD
92static __int64_t switch_count = 0;
93static __int64_t preempt_hit = 0;
94static __int64_t preempt_miss = 0;
95static __int64_t preempt_weird = 0;
f64b567c 96static __int64_t token_contention_count __debugvar = 0;
fb0f29c4 97static int lwkt_use_spin_port;
40aaf5fc 98static struct objcache *thread_cache;
05220613 99
88ebb169 100#ifdef SMP
e381e77c 101static void lwkt_schedule_remote(void *arg, int arg2, struct intrframe *frame);
88ebb169 102#endif
f9235b6d 103static void lwkt_fairq_accumulate(globaldata_t gd, thread_t td);
e381e77c 104
0855a2af
JG
105extern void cpu_heavy_restore(void);
106extern void cpu_lwkt_restore(void);
107extern void cpu_kthread_restore(void);
108extern void cpu_idle_restore(void);
109
b2b3ffcd 110#ifdef __x86_64__
85514115
MD
111
112static int
0855a2af
JG
113jg_tos_ok(struct thread *td)
114{
85514115
MD
115 void *tos;
116 int tos_ok;
117
0855a2af
JG
118 if (td == NULL) {
119 return 1;
120 }
121 KKASSERT(td->td_sp != NULL);
85514115
MD
122 tos = ((void **)td->td_sp)[0];
123 tos_ok = 0;
124 if ((tos == cpu_heavy_restore) || (tos == cpu_lwkt_restore) ||
125 (tos == cpu_kthread_restore) || (tos == cpu_idle_restore)) {
0855a2af
JG
126 tos_ok = 1;
127 }
128 return tos_ok;
129}
130
85514115
MD
131#endif
132
fb0f29c4
MD
133/*
134 * We can make all thread ports use the spin backend instead of the thread
135 * backend. This should only be set to debug the spin backend.
136 */
137TUNABLE_INT("lwkt.use_spin_port", &lwkt_use_spin_port);
138
0f7a3396
MD
139#ifdef INVARIANTS
140SYSCTL_INT(_lwkt, OID_AUTO, panic_on_cscount, CTLFLAG_RW, &panic_on_cscount, 0, "");
141#endif
4b5f931b 142SYSCTL_QUAD(_lwkt, OID_AUTO, switch_count, CTLFLAG_RW, &switch_count, 0, "");
9733f757
VS
143SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_hit, CTLFLAG_RW, &preempt_hit, 0,
144 "Successful preemption events");
145SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_miss, CTLFLAG_RW, &preempt_miss, 0,
146 "Failed preemption events");
26a0694b 147SYSCTL_QUAD(_lwkt, OID_AUTO, preempt_weird, CTLFLAG_RW, &preempt_weird, 0, "");
38717797
HP
148#ifdef INVARIANTS
149SYSCTL_QUAD(_lwkt, OID_AUTO, token_contention_count, CTLFLAG_RW,
150 &token_contention_count, 0, "spinning due to token contention");
38717797 151#endif
f9235b6d
MD
152static int fairq_enable = 1;
153SYSCTL_INT(_lwkt, OID_AUTO, fairq_enable, CTLFLAG_RW, &fairq_enable, 0, "");
77912481
MD
154static int user_pri_sched = 0;
155SYSCTL_INT(_lwkt, OID_AUTO, user_pri_sched, CTLFLAG_RW, &user_pri_sched, 0, "");
05220613 156
4b5f931b
MD
157/*
158 * These helper procedures handle the runq, they can only be called from
159 * within a critical section.
75cdbe6c
MD
160 *
161 * WARNING! Prior to SMP being brought up it is possible to enqueue and
162 * dequeue threads belonging to other cpus, so be sure to use td->td_gd
163 * instead of 'mycpu' when referencing the globaldata structure. Once
164 * SMP live enqueuing and dequeueing only occurs on the current cpu.
4b5f931b 165 */
f1d1c3fa
MD
166static __inline
167void
168_lwkt_dequeue(thread_t td)
169{
170 if (td->td_flags & TDF_RUNQ) {
75cdbe6c 171 struct globaldata *gd = td->td_gd;
4b5f931b 172
f1d1c3fa 173 td->td_flags &= ~TDF_RUNQ;
f9235b6d
MD
174 TAILQ_REMOVE(&gd->gd_tdrunq, td, td_threadq);
175 gd->gd_fairq_total_pri -= td->td_pri;
176 if (TAILQ_FIRST(&gd->gd_tdrunq) == NULL)
177 atomic_clear_int_nonlocked(&gd->gd_reqflags, RQF_RUNNING);
f1d1c3fa
MD
178 }
179}
180
f9235b6d
MD
181/*
182 * Priority enqueue.
183 *
184 * NOTE: There are a limited number of lwkt threads runnable since user
185 * processes only schedule one at a time per cpu.
186 */
f1d1c3fa
MD
187static __inline
188void
189_lwkt_enqueue(thread_t td)
190{
f9235b6d
MD
191 thread_t xtd;
192
7f5d7ed7 193 if ((td->td_flags & (TDF_RUNQ|TDF_MIGRATING|TDF_BLOCKQ)) == 0) {
75cdbe6c 194 struct globaldata *gd = td->td_gd;
4b5f931b 195
f1d1c3fa 196 td->td_flags |= TDF_RUNQ;
f9235b6d
MD
197 xtd = TAILQ_FIRST(&gd->gd_tdrunq);
198 if (xtd == NULL) {
199 TAILQ_INSERT_TAIL(&gd->gd_tdrunq, td, td_threadq);
200 atomic_set_int_nonlocked(&gd->gd_reqflags, RQF_RUNNING);
201 } else {
202 while (xtd && xtd->td_pri > td->td_pri)
203 xtd = TAILQ_NEXT(xtd, td_threadq);
204 if (xtd)
205 TAILQ_INSERT_BEFORE(xtd, td, td_threadq);
206 else
207 TAILQ_INSERT_TAIL(&gd->gd_tdrunq, td, td_threadq);
208 }
209 gd->gd_fairq_total_pri += td->td_pri;
f1d1c3fa
MD
210 }
211}
8ad65e08 212
40aaf5fc
NT
213static __boolean_t
214_lwkt_thread_ctor(void *obj, void *privdata, int ocflags)
215{
216 struct thread *td = (struct thread *)obj;
217
218 td->td_kstack = NULL;
219 td->td_kstack_size = 0;
220 td->td_flags = TDF_ALLOCATED_THREAD;
221 return (1);
222}
223
224static void
225_lwkt_thread_dtor(void *obj, void *privdata)
226{
227 struct thread *td = (struct thread *)obj;
228
229 KASSERT(td->td_flags & TDF_ALLOCATED_THREAD,
230 ("_lwkt_thread_dtor: not allocated from objcache"));
231 KASSERT((td->td_flags & TDF_ALLOCATED_STACK) && td->td_kstack &&
232 td->td_kstack_size > 0,
233 ("_lwkt_thread_dtor: corrupted stack"));
234 kmem_free(&kernel_map, (vm_offset_t)td->td_kstack, td->td_kstack_size);
235}
236
237/*
238 * Initialize the lwkt s/system.
239 */
240void
241lwkt_init(void)
242{
243 /* An objcache has 2 magazines per CPU so divide cache size by 2. */
0aa16b5d
SZ
244 thread_cache = objcache_create_mbacked(M_THREAD, sizeof(struct thread),
245 NULL, CACHE_NTHREADS/2,
246 _lwkt_thread_ctor, _lwkt_thread_dtor, NULL);
40aaf5fc
NT
247}
248
37af14fe
MD
249/*
250 * Schedule a thread to run. As the current thread we can always safely
251 * schedule ourselves, and a shortcut procedure is provided for that
252 * function.
253 *
254 * (non-blocking, self contained on a per cpu basis)
255 */
256void
257lwkt_schedule_self(thread_t td)
258{
259 crit_enter_quick(td);
f9235b6d
MD
260 KASSERT(td != &td->td_gd->gd_idlethread,
261 ("lwkt_schedule_self(): scheduling gd_idlethread is illegal!"));
9388413d 262 KKASSERT(td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0);
37af14fe 263 _lwkt_enqueue(td);
37af14fe
MD
264 crit_exit_quick(td);
265}
266
267/*
268 * Deschedule a thread.
269 *
270 * (non-blocking, self contained on a per cpu basis)
271 */
272void
273lwkt_deschedule_self(thread_t td)
274{
275 crit_enter_quick(td);
37af14fe
MD
276 _lwkt_dequeue(td);
277 crit_exit_quick(td);
278}
279
8ad65e08
MD
280/*
281 * LWKTs operate on a per-cpu basis
282 *
73e4f7b9 283 * WARNING! Called from early boot, 'mycpu' may not work yet.
8ad65e08
MD
284 */
285void
286lwkt_gdinit(struct globaldata *gd)
287{
f9235b6d 288 TAILQ_INIT(&gd->gd_tdrunq);
73e4f7b9 289 TAILQ_INIT(&gd->gd_tdallq);
8ad65e08
MD
290}
291
292/*
7d0bac62 293 * Create a new thread. The thread must be associated with a process context
75cdbe6c
MD
294 * or LWKT start address before it can be scheduled. If the target cpu is
295 * -1 the thread will be created on the current cpu.
0cfcada1
MD
296 *
297 * If you intend to create a thread without a process context this function
298 * does everything except load the startup and switcher function.
7d0bac62
MD
299 */
300thread_t
d3d32139 301lwkt_alloc_thread(struct thread *td, int stksize, int cpu, int flags)
7d0bac62 302{
c070746a 303 globaldata_t gd = mycpu;
99df837e 304 void *stack;
7d0bac62 305
c070746a
MD
306 /*
307 * If static thread storage is not supplied allocate a thread. Reuse
308 * a cached free thread if possible. gd_freetd is used to keep an exiting
309 * thread intact through the exit.
310 */
ef0fdad1 311 if (td == NULL) {
c070746a
MD
312 if ((td = gd->gd_freetd) != NULL)
313 gd->gd_freetd = NULL;
314 else
315 td = objcache_get(thread_cache, M_WAITOK);
40aaf5fc
NT
316 KASSERT((td->td_flags &
317 (TDF_ALLOCATED_THREAD|TDF_RUNNING)) == TDF_ALLOCATED_THREAD,
318 ("lwkt_alloc_thread: corrupted td flags 0x%X", td->td_flags));
319 flags |= td->td_flags & (TDF_ALLOCATED_THREAD|TDF_ALLOCATED_STACK);
ef0fdad1 320 }
c070746a
MD
321
322 /*
323 * Try to reuse cached stack.
324 */
f470d0c8
MD
325 if ((stack = td->td_kstack) != NULL && td->td_kstack_size != stksize) {
326 if (flags & TDF_ALLOCATED_STACK) {
e4846942 327 kmem_free(&kernel_map, (vm_offset_t)stack, td->td_kstack_size);
f470d0c8
MD
328 stack = NULL;
329 }
330 }
331 if (stack == NULL) {
e4846942 332 stack = (void *)kmem_alloc(&kernel_map, stksize);
ef0fdad1 333 flags |= TDF_ALLOCATED_STACK;
99df837e 334 }
75cdbe6c 335 if (cpu < 0)
c070746a 336 lwkt_init_thread(td, stack, stksize, flags, gd);
75cdbe6c 337 else
f470d0c8 338 lwkt_init_thread(td, stack, stksize, flags, globaldata_find(cpu));
99df837e 339 return(td);
7d0bac62
MD
340}
341
342/*
343 * Initialize a preexisting thread structure. This function is used by
344 * lwkt_alloc_thread() and also used to initialize the per-cpu idlethread.
345 *
f8c3996b
MD
346 * All threads start out in a critical section at a priority of
347 * TDPRI_KERN_DAEMON. Higher level code will modify the priority as
75cdbe6c
MD
348 * appropriate. This function may send an IPI message when the
349 * requested cpu is not the current cpu and consequently gd_tdallq may
350 * not be initialized synchronously from the point of view of the originating
351 * cpu.
352 *
353 * NOTE! we have to be careful in regards to creating threads for other cpus
354 * if SMP has not yet been activated.
7d0bac62 355 */
41a01a4d
MD
356#ifdef SMP
357
75cdbe6c
MD
358static void
359lwkt_init_thread_remote(void *arg)
360{
361 thread_t td = arg;
362
52eedfb5
MD
363 /*
364 * Protected by critical section held by IPI dispatch
365 */
75cdbe6c
MD
366 TAILQ_INSERT_TAIL(&td->td_gd->gd_tdallq, td, td_allq);
367}
368
41a01a4d
MD
369#endif
370
fdce8919
MD
371/*
372 * lwkt core thread structural initialization.
373 *
374 * NOTE: All threads are initialized as mpsafe threads.
375 */
7d0bac62 376void
f470d0c8
MD
377lwkt_init_thread(thread_t td, void *stack, int stksize, int flags,
378 struct globaldata *gd)
7d0bac62 379{
37af14fe
MD
380 globaldata_t mygd = mycpu;
381
99df837e
MD
382 bzero(td, sizeof(struct thread));
383 td->td_kstack = stack;
f470d0c8 384 td->td_kstack_size = stksize;
d3d32139 385 td->td_flags = flags;
26a0694b 386 td->td_gd = gd;
f9235b6d
MD
387 td->td_pri = TDPRI_KERN_DAEMON;
388 td->td_critcount = 1;
3b998fa9 389 td->td_toks_stop = &td->td_toks_base;
fb0f29c4
MD
390 if (lwkt_use_spin_port)
391 lwkt_initport_spin(&td->td_msgport);
392 else
393 lwkt_initport_thread(&td->td_msgport, td);
99df837e 394 pmap_init_thread(td);
0f7a3396 395#ifdef SMP
5d21b981
MD
396 /*
397 * Normally initializing a thread for a remote cpu requires sending an
398 * IPI. However, the idlethread is setup before the other cpus are
399 * activated so we have to treat it as a special case. XXX manipulation
400 * of gd_tdallq requires the BGL.
401 */
402 if (gd == mygd || td == &gd->gd_idlethread) {
37af14fe 403 crit_enter_gd(mygd);
75cdbe6c 404 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
37af14fe 405 crit_exit_gd(mygd);
75cdbe6c 406 } else {
2db3b277 407 lwkt_send_ipiq(gd, lwkt_init_thread_remote, td);
75cdbe6c 408 }
0f7a3396 409#else
37af14fe 410 crit_enter_gd(mygd);
0f7a3396 411 TAILQ_INSERT_TAIL(&gd->gd_tdallq, td, td_allq);
37af14fe 412 crit_exit_gd(mygd);
0f7a3396 413#endif
8c72e3d5
AH
414
415 dsched_new_thread(td);
73e4f7b9
MD
416}
417
418void
419lwkt_set_comm(thread_t td, const char *ctl, ...)
420{
e2565a42 421 __va_list va;
73e4f7b9 422
e2565a42 423 __va_start(va, ctl);
379210cb 424 kvsnprintf(td->td_comm, sizeof(td->td_comm), ctl, va);
e2565a42 425 __va_end(va);
e7c0dbba 426 KTR_LOG(ctxsw_newtd, td, &td->td_comm[0]);
7d0bac62
MD
427}
428
99df837e 429void
73e4f7b9 430lwkt_hold(thread_t td)
99df837e 431{
73e4f7b9
MD
432 ++td->td_refs;
433}
434
435void
436lwkt_rele(thread_t td)
437{
438 KKASSERT(td->td_refs > 0);
439 --td->td_refs;
440}
441
442void
443lwkt_wait_free(thread_t td)
444{
445 while (td->td_refs)
377d4740 446 tsleep(td, 0, "tdreap", hz);
73e4f7b9
MD
447}
448
449void
450lwkt_free_thread(thread_t td)
451{
d9eea1a5 452 KASSERT((td->td_flags & TDF_RUNNING) == 0,
99df837e
MD
453 ("lwkt_free_thread: did not exit! %p", td));
454
40aaf5fc
NT
455 if (td->td_flags & TDF_ALLOCATED_THREAD) {
456 objcache_put(thread_cache, td);
457 } else if (td->td_flags & TDF_ALLOCATED_STACK) {
458 /* client-allocated struct with internally allocated stack */
459 KASSERT(td->td_kstack && td->td_kstack_size > 0,
460 ("lwkt_free_thread: corrupted stack"));
461 kmem_free(&kernel_map, (vm_offset_t)td->td_kstack, td->td_kstack_size);
462 td->td_kstack = NULL;
463 td->td_kstack_size = 0;
99df837e 464 }
e7c0dbba 465 KTR_LOG(ctxsw_deadtd, td);
99df837e
MD
466}
467
468
7d0bac62 469/*
8ad65e08 470 * Switch to the next runnable lwkt. If no LWKTs are runnable then
f1d1c3fa
MD
471 * switch to the idlethread. Switching must occur within a critical
472 * section to avoid races with the scheduling queue.
473 *
474 * We always have full control over our cpu's run queue. Other cpus
475 * that wish to manipulate our queue must use the cpu_*msg() calls to
476 * talk to our cpu, so a critical section is all that is needed and
477 * the result is very, very fast thread switching.
478 *
96728c05
MD
479 * The LWKT scheduler uses a fixed priority model and round-robins at
480 * each priority level. User process scheduling is a totally
481 * different beast and LWKT priorities should not be confused with
482 * user process priorities.
f1d1c3fa 483 *
96728c05
MD
484 * The MP lock may be out of sync with the thread's td_mpcount. lwkt_switch()
485 * cleans it up. Note that the td_switch() function cannot do anything that
486 * requires the MP lock since the MP lock will have already been setup for
71ef2f5c
MD
487 * the target thread (not the current thread). It's nice to have a scheduler
488 * that does not need the MP lock to work because it allows us to do some
489 * really cool high-performance MP lock optimizations.
69d78e99
MD
490 *
491 * PREEMPTION NOTE: Preemption occurs via lwkt_preempt(). lwkt_switch()
492 * is not called by the current thread in the preemption case, only when
493 * the preempting thread blocks (in order to return to the original thread).
8ad65e08
MD
494 */
495void
496lwkt_switch(void)
497{
37af14fe
MD
498 globaldata_t gd = mycpu;
499 thread_t td = gd->gd_curthread;
8ad65e08 500 thread_t ntd;
f9235b6d
MD
501 thread_t xtd;
502 thread_t nlast;
f9235b6d 503 int nquserok;
6f207a2c 504#ifdef SMP
8a8d5d85
MD
505 int mpheld;
506#endif
f9235b6d 507 int didaccumulate;
b37f18d6
MD
508 const char *lmsg; /* diagnostic - 'systat -pv 1' */
509 const void *laddr;
8ad65e08 510
46a3f46d 511 /*
27e88a6e
MD
512 * Switching from within a 'fast' (non thread switched) interrupt or IPI
513 * is illegal. However, we may have to do it anyway if we hit a fatal
514 * kernel trap or we have paniced.
515 *
516 * If this case occurs save and restore the interrupt nesting level.
46a3f46d 517 */
27e88a6e
MD
518 if (gd->gd_intr_nesting_level) {
519 int savegdnest;
520 int savegdtrap;
521
522 if (gd->gd_trap_nesting_level == 0 && panicstr == NULL) {
4a28fe22
MD
523 panic("lwkt_switch: Attempt to switch from a "
524 "a fast interrupt, ipi, or hard code section, "
525 "td %p\n",
526 td);
27e88a6e
MD
527 } else {
528 savegdnest = gd->gd_intr_nesting_level;
529 savegdtrap = gd->gd_trap_nesting_level;
530 gd->gd_intr_nesting_level = 0;
531 gd->gd_trap_nesting_level = 0;
a7422615
MD
532 if ((td->td_flags & TDF_PANICWARN) == 0) {
533 td->td_flags |= TDF_PANICWARN;
4a28fe22
MD
534 kprintf("Warning: thread switch from interrupt, IPI, "
535 "or hard code section.\n"
a7422615 536 "thread %p (%s)\n", td, td->td_comm);
7ce2998e 537 print_backtrace(-1);
a7422615 538 }
27e88a6e
MD
539 lwkt_switch();
540 gd->gd_intr_nesting_level = savegdnest;
541 gd->gd_trap_nesting_level = savegdtrap;
542 return;
543 }
96728c05 544 }
ef0fdad1 545
cb973d15
MD
546 /*
547 * Passive release (used to transition from user to kernel mode
548 * when we block or switch rather then when we enter the kernel).
549 * This function is NOT called if we are switching into a preemption
550 * or returning from a preemption. Typically this causes us to lose
0a3f9b47
MD
551 * our current process designation (if we have one) and become a true
552 * LWKT thread, and may also hand the current process designation to
553 * another process and schedule thread.
cb973d15
MD
554 */
555 if (td->td_release)
556 td->td_release(td);
557
37af14fe 558 crit_enter_gd(gd);
3b998fa9 559 if (TD_TOKS_HELD(td))
9d265729
MD
560 lwkt_relalltokens(td);
561
562 /*
b02926de
MD
563 * We had better not be holding any spin locks, but don't get into an
564 * endless panic loop.
9d265729 565 */
bbb31c5d
MD
566 KASSERT(gd->gd_spinlock_rd == NULL || panicstr != NULL,
567 ("lwkt_switch: still holding a shared spinlock %p!",
568 gd->gd_spinlock_rd));
d666840a
MD
569 KASSERT(gd->gd_spinlocks_wr == 0 || panicstr != NULL,
570 ("lwkt_switch: still holding %d exclusive spinlocks!",
571 gd->gd_spinlocks_wr));
9d265729 572
8a8d5d85
MD
573
574#ifdef SMP
575 /*
576 * td_mpcount cannot be used to determine if we currently hold the
577 * MP lock because get_mplock() will increment it prior to attempting
71ef2f5c
MD
578 * to get the lock, and switch out if it can't. Our ownership of
579 * the actual lock will remain stable while we are in a critical section
580 * (but, of course, another cpu may own or release the lock so the
581 * actual value of mp_lock is not stable).
8a8d5d85 582 */
c5724852 583 mpheld = MP_LOCK_HELD(gd);
0f7a3396
MD
584#ifdef INVARIANTS
585 if (td->td_cscount) {
6ea70f76 586 kprintf("Diagnostic: attempt to switch while mastering cpusync: %p\n",
0f7a3396
MD
587 td);
588 if (panic_on_cscount)
589 panic("switching while mastering cpusync");
590 }
591#endif
8a8d5d85 592#endif
f9235b6d
MD
593
594 /*
595 * If we had preempted another thread on this cpu, resume the preempted
596 * thread. This occurs transparently, whether the preempted thread
597 * was scheduled or not (it may have been preempted after descheduling
598 * itself).
599 *
600 * We have to setup the MP lock for the original thread after backing
601 * out the adjustment that was made to curthread when the original
602 * was preempted.
603 */
99df837e 604 if ((ntd = td->td_preempted) != NULL) {
26a0694b 605 KKASSERT(ntd->td_flags & TDF_PREEMPT_LOCK);
8a8d5d85 606#ifdef SMP
96728c05 607 if (ntd->td_mpcount && mpheld == 0) {
fc92d4aa 608 panic("MPLOCK NOT HELD ON RETURN: %p %p %d %d",
96728c05
MD
609 td, ntd, td->td_mpcount, ntd->td_mpcount);
610 }
8a8d5d85
MD
611 if (ntd->td_mpcount) {
612 td->td_mpcount -= ntd->td_mpcount;
613 KKASSERT(td->td_mpcount >= 0);
614 }
615#endif
26a0694b 616 ntd->td_flags |= TDF_PREEMPT_DONE;
8ec60c3f
MD
617
618 /*
b9eb1c19
MD
619 * The interrupt may have woken a thread up, we need to properly
620 * set the reschedule flag if the originally interrupted thread is
621 * at a lower priority.
8ec60c3f 622 */
f9235b6d
MD
623 if (TAILQ_FIRST(&gd->gd_tdrunq) &&
624 TAILQ_FIRST(&gd->gd_tdrunq)->td_pri > ntd->td_pri) {
8ec60c3f 625 need_lwkt_resched();
f9235b6d 626 }
8a8d5d85 627 /* YYY release mp lock on switchback if original doesn't need it */
f9235b6d
MD
628 goto havethread_preempted;
629 }
630
631 /*
632 * Implement round-robin fairq with priority insertion. The priority
633 * insertion is handled by _lwkt_enqueue()
634 *
635 * We have to adjust the MP lock for the target thread. If we
636 * need the MP lock and cannot obtain it we try to locate a
637 * thread that does not need the MP lock. If we cannot, we spin
638 * instead of HLT.
639 *
640 * A similar issue exists for the tokens held by the target thread.
641 * If we cannot obtain ownership of the tokens we cannot immediately
642 * schedule the thread.
643 */
644 for (;;) {
645 clear_lwkt_resched();
646 didaccumulate = 0;
647 ntd = TAILQ_FIRST(&gd->gd_tdrunq);
648
4b5f931b 649 /*
f9235b6d 650 * Hotpath if we can get all necessary resources.
41a01a4d 651 *
f9235b6d 652 * If nothing is runnable switch to the idle thread
41a01a4d 653 */
f9235b6d
MD
654 if (ntd == NULL) {
655 ntd = &gd->gd_idlethread;
656 if (gd->gd_reqflags & RQF_IDLECHECK_MASK)
657 ntd->td_flags |= TDF_IDLE_NOHLT;
6f207a2c 658#ifdef SMP
f9235b6d
MD
659 if (ntd->td_mpcount) {
660 if (gd->gd_trap_nesting_level == 0 && panicstr == NULL)
661 panic("Idle thread %p was holding the BGL!", ntd);
662 if (mpheld == 0) {
c5724852
MD
663 set_cpu_contention_mask(gd);
664 handle_cpu_contention_mask();
665 cpu_try_mplock();
666 mpheld = MP_LOCK_HELD(gd);
f9235b6d
MD
667 cpu_pause();
668 continue;
669 }
670 }
c5724852 671 clr_cpu_contention_mask(gd);
6f207a2c 672#endif
b37f18d6
MD
673 cpu_time.cp_msg[0] = 0;
674 cpu_time.cp_stallpc = 0;
f9235b6d
MD
675 goto haveidle;
676 }
41a01a4d
MD
677
678 /*
f9235b6d 679 * Hotpath schedule
6f207a2c
MD
680 *
681 * NOTE: For UP there is no mplock and lwkt_getalltokens()
682 * always succeeds.
8ec60c3f 683 */
f9235b6d
MD
684 if (ntd->td_fairq_accum >= 0 &&
685#ifdef SMP
686 (ntd->td_mpcount == 0 || mpheld || cpu_try_mplock()) &&
687#endif
b37f18d6 688 (!TD_TOKS_HELD(ntd) || lwkt_getalltokens(ntd, &lmsg, &laddr))
f9235b6d 689 ) {
8a8d5d85 690#ifdef SMP
c5724852 691 clr_cpu_contention_mask(gd);
f9235b6d
MD
692#endif
693 goto havethread;
694 }
695
b37f18d6
MD
696 lmsg = NULL;
697 laddr = NULL;
698
f9235b6d 699#ifdef SMP
c5724852
MD
700 if (ntd->td_fairq_accum >= 0)
701 set_cpu_contention_mask(gd);
f9235b6d 702 /* Reload mpheld (it become stale after mplock/token ops) */
c5724852 703 mpheld = MP_LOCK_HELD(gd);
b37f18d6
MD
704 if (ntd->td_mpcount && mpheld == 0) {
705 lmsg = "mplock";
706 laddr = ntd->td_mplock_stallpc;
707 }
f9235b6d
MD
708#endif
709
710 /*
711 * Coldpath - unable to schedule ntd, continue looking for threads
712 * to schedule. This is only allowed of the (presumably) kernel
713 * thread exhausted its fair share. A kernel thread stuck on
714 * resources does not currently allow a user thread to get in
715 * front of it.
716 */
717#ifdef SMP
718 nquserok = ((ntd->td_pri < TDPRI_KERN_LPSCHED) ||
719 (ntd->td_fairq_accum < 0));
6f207a2c
MD
720#else
721 nquserok = 1;
f9235b6d
MD
722#endif
723 nlast = NULL;
724
725 for (;;) {
41a01a4d 726 /*
f9235b6d
MD
727 * If the fair-share scheduler ran out ntd gets moved to the
728 * end and its accumulator will be bumped, if it didn't we
729 * maintain the same queue position.
df6b8ba0 730 *
f9235b6d 731 * nlast keeps track of the last element prior to any moves.
41a01a4d 732 */
f9235b6d 733 if (ntd->td_fairq_accum < 0) {
f9235b6d
MD
734 lwkt_fairq_accumulate(gd, ntd);
735 didaccumulate = 1;
c5724852
MD
736
737 /*
738 * Move to end
739 */
740 xtd = TAILQ_NEXT(ntd, td_threadq);
f9235b6d
MD
741 TAILQ_REMOVE(&gd->gd_tdrunq, ntd, td_threadq);
742 TAILQ_INSERT_TAIL(&gd->gd_tdrunq, ntd, td_threadq);
c5724852
MD
743
744 /*
745 * Set terminal element (nlast)
746 */
f9235b6d
MD
747 if (nlast == NULL) {
748 nlast = ntd;
749 if (xtd == NULL)
750 xtd = ntd;
751 }
752 ntd = xtd;
753 } else {
754 ntd = TAILQ_NEXT(ntd, td_threadq);
755 }
a453459d 756
f9235b6d
MD
757 /*
758 * If we exhausted the run list switch to the idle thread.
759 * Since one or more threads had resource acquisition issues
760 * we do not allow the idle thread to halt.
761 *
762 * NOTE: nlast can be NULL.
763 */
764 if (ntd == nlast) {
e0a90d3b 765 cpu_pause();
f9235b6d
MD
766 ntd = &gd->gd_idlethread;
767 ntd->td_flags |= TDF_IDLE_NOHLT;
6f207a2c 768#ifdef SMP
f9235b6d 769 if (ntd->td_mpcount) {
c5724852 770 mpheld = MP_LOCK_HELD(gd);
f9235b6d
MD
771 if (gd->gd_trap_nesting_level == 0 && panicstr == NULL)
772 panic("Idle thread %p was holding the BGL!", ntd);
773 if (mpheld == 0) {
c5724852
MD
774 set_cpu_contention_mask(gd);
775 handle_cpu_contention_mask();
776 cpu_try_mplock();
777 mpheld = MP_LOCK_HELD(gd);
f9235b6d
MD
778 cpu_pause();
779 break; /* try again from the top, almost */
b9eb1c19 780 }
8a8d5d85 781 }
6f207a2c 782#endif
684a93c4
MD
783
784 /*
f9235b6d
MD
785 * If fairq accumulations occured we do not schedule the
786 * idle thread. This will cause us to try again from
787 * the (almost) top.
684a93c4 788 */
f9235b6d 789 if (didaccumulate)
b37f18d6
MD
790 break; /* try again from the top, almost */
791 if (lmsg)
792 strlcpy(cpu_time.cp_msg, lmsg, sizeof(cpu_time.cp_msg));
793 cpu_time.cp_stallpc = (uintptr_t)laddr;
f9235b6d 794 goto haveidle;
8a8d5d85 795 }
f9235b6d 796
df6b8ba0 797 /*
f9235b6d 798 * Try to switch to this thread.
6f207a2c
MD
799 *
800 * NOTE: For UP there is no mplock and lwkt_getalltokens()
801 * always succeeds.
df6b8ba0 802 */
77912481
MD
803 if ((ntd->td_pri >= TDPRI_KERN_LPSCHED || nquserok ||
804 user_pri_sched) && ntd->td_fairq_accum >= 0 &&
f9235b6d
MD
805#ifdef SMP
806 (ntd->td_mpcount == 0 || mpheld || cpu_try_mplock()) &&
8a8d5d85 807#endif
b37f18d6 808 (!TD_TOKS_HELD(ntd) || lwkt_getalltokens(ntd, &lmsg, &laddr))
f9235b6d 809 ) {
a453459d 810#ifdef SMP
c5724852 811 clr_cpu_contention_mask(gd);
f9235b6d
MD
812#endif
813 goto havethread;
df6b8ba0 814 }
f9235b6d 815#ifdef SMP
c5724852
MD
816 if (ntd->td_fairq_accum >= 0)
817 set_cpu_contention_mask(gd);
818 /*
819 * Reload mpheld (it become stale after mplock/token ops).
820 */
821 mpheld = MP_LOCK_HELD(gd);
b37f18d6
MD
822 if (ntd->td_mpcount && mpheld == 0) {
823 lmsg = "mplock";
824 laddr = ntd->td_mplock_stallpc;
825 }
f9235b6d
MD
826 if (ntd->td_pri >= TDPRI_KERN_LPSCHED && ntd->td_fairq_accum >= 0)
827 nquserok = 0;
a453459d 828#endif
4b5f931b 829 }
c5724852
MD
830
831 /*
832 * All threads exhausted but we can loop due to a negative
833 * accumulator.
834 *
835 * While we are looping in the scheduler be sure to service
836 * any interrupts which were made pending due to our critical
837 * section, otherwise we could livelock (e.g.) IPIs.
838 *
839 * NOTE: splz can enter and exit the mplock so mpheld is
840 * stale after this call.
841 */
842 splz_check();
843
844#ifdef SMP
845 /*
846 * Our mplock can be cached and cause other cpus to livelock
847 * if we loop due to e.g. not being able to acquire tokens.
848 */
849 if (MP_LOCK_HELD(gd))
850 cpu_rel_mplock(gd->gd_cpuid);
851 mpheld = 0;
852#endif
f1d1c3fa 853 }
8a8d5d85
MD
854
855 /*
f9235b6d
MD
856 * Do the actual switch. WARNING: mpheld is stale here.
857 *
858 * We must always decrement td_fairq_accum on non-idle threads just
859 * in case a thread never gets a tick due to being in a continuous
860 * critical section. The page-zeroing code does that.
861 *
862 * If the thread we came up with is a higher or equal priority verses
863 * the thread at the head of the queue we move our thread to the
864 * front. This way we can always check the front of the queue.
865 */
866havethread:
867 ++gd->gd_cnt.v_swtch;
868 --ntd->td_fairq_accum;
869 xtd = TAILQ_FIRST(&gd->gd_tdrunq);
870 if (ntd != xtd && ntd->td_pri >= xtd->td_pri) {
871 TAILQ_REMOVE(&gd->gd_tdrunq, ntd, td_threadq);
872 TAILQ_INSERT_HEAD(&gd->gd_tdrunq, ntd, td_threadq);
873 }
874havethread_preempted:
875 ;
876 /*
877 * If the new target does not need the MP lock and we are holding it,
878 * release the MP lock. If the new target requires the MP lock we have
879 * already acquired it for the target.
880 *
881 * WARNING: mpheld is stale here.
8a8d5d85 882 */
f9235b6d
MD
883haveidle:
884 KASSERT(ntd->td_critcount,
885 ("priority problem in lwkt_switch %d %d", td->td_pri, ntd->td_pri));
8a8d5d85
MD
886#ifdef SMP
887 if (ntd->td_mpcount == 0 ) {
c5724852
MD
888 if (MP_LOCK_HELD(gd))
889 cpu_rel_mplock(gd->gd_cpuid);
8a8d5d85 890 } else {
a453459d 891 ASSERT_MP_LOCK_HELD(ntd);
8a8d5d85
MD
892 }
893#endif
94f6d86e
MD
894 if (td != ntd) {
895 ++switch_count;
b2b3ffcd 896#ifdef __x86_64__
f9235b6d
MD
897 {
898 int tos_ok __debugvar = jg_tos_ok(ntd);
899 KKASSERT(tos_ok);
900 }
85514115 901#endif
a1f0fb66 902 KTR_LOG(ctxsw_sw, gd->gd_cpuid, ntd);
f1d1c3fa 903 td->td_switch(ntd);
94f6d86e 904 }
37af14fe
MD
905 /* NOTE: current cpu may have changed after switch */
906 crit_exit_quick(td);
8ad65e08
MD
907}
908
f1d1c3fa 909/*
96728c05
MD
910 * Request that the target thread preempt the current thread. Preemption
911 * only works under a specific set of conditions:
b68b7282 912 *
96728c05
MD
913 * - We are not preempting ourselves
914 * - The target thread is owned by the current cpu
915 * - We are not currently being preempted
916 * - The target is not currently being preempted
d3d1cbc8
MD
917 * - We are not holding any spin locks
918 * - The target thread is not holding any tokens
96728c05
MD
919 * - We are able to satisfy the target's MP lock requirements (if any).
920 *
921 * THE CALLER OF LWKT_PREEMPT() MUST BE IN A CRITICAL SECTION. Typically
922 * this is called via lwkt_schedule() through the td_preemptable callback.
f9235b6d 923 * critcount is the managed critical priority that we should ignore in order
96728c05
MD
924 * to determine whether preemption is possible (aka usually just the crit
925 * priority of lwkt_schedule() itself).
b68b7282 926 *
26a0694b
MD
927 * XXX at the moment we run the target thread in a critical section during
928 * the preemption in order to prevent the target from taking interrupts
929 * that *WE* can't. Preemption is strictly limited to interrupt threads
930 * and interrupt-like threads, outside of a critical section, and the
931 * preempted source thread will be resumed the instant the target blocks
932 * whether or not the source is scheduled (i.e. preemption is supposed to
933 * be as transparent as possible).
4b5f931b 934 *
8a8d5d85
MD
935 * The target thread inherits our MP count (added to its own) for the
936 * duration of the preemption in order to preserve the atomicy of the
96728c05
MD
937 * MP lock during the preemption. Therefore, any preempting targets must be
938 * careful in regards to MP assertions. Note that the MP count may be
71ef2f5c
MD
939 * out of sync with the physical mp_lock, but we do not have to preserve
940 * the original ownership of the lock if it was out of synch (that is, we
941 * can leave it synchronized on return).
b68b7282
MD
942 */
943void
f9235b6d 944lwkt_preempt(thread_t ntd, int critcount)
b68b7282 945{
46a3f46d 946 struct globaldata *gd = mycpu;
0a3f9b47 947 thread_t td;
8a8d5d85
MD
948#ifdef SMP
949 int mpheld;
57c254db 950 int savecnt;
8a8d5d85 951#endif
b68b7282 952
26a0694b 953 /*
96728c05
MD
954 * The caller has put us in a critical section. We can only preempt
955 * if the caller of the caller was not in a critical section (basically
f9235b6d 956 * a local interrupt), as determined by the 'critcount' parameter. We
47737962 957 * also can't preempt if the caller is holding any spinlocks (even if
d666840a 958 * he isn't in a critical section). This also handles the tokens test.
96728c05
MD
959 *
960 * YYY The target thread must be in a critical section (else it must
961 * inherit our critical section? I dunno yet).
41a01a4d 962 *
0a3f9b47 963 * Set need_lwkt_resched() unconditionally for now YYY.
26a0694b 964 */
f9235b6d 965 KASSERT(ntd->td_critcount, ("BADCRIT0 %d", ntd->td_pri));
26a0694b 966
0a3f9b47 967 td = gd->gd_curthread;
f9235b6d 968 if (ntd->td_pri <= td->td_pri) {
57c254db
MD
969 ++preempt_miss;
970 return;
971 }
f9235b6d 972 if (td->td_critcount > critcount) {
96728c05 973 ++preempt_miss;
8ec60c3f 974 need_lwkt_resched();
96728c05
MD
975 return;
976 }
977#ifdef SMP
46a3f46d 978 if (ntd->td_gd != gd) {
96728c05 979 ++preempt_miss;
8ec60c3f 980 need_lwkt_resched();
96728c05
MD
981 return;
982 }
983#endif
41a01a4d 984 /*
77912481
MD
985 * We don't have to check spinlocks here as they will also bump
986 * td_critcount.
d3d1cbc8
MD
987 *
988 * Do not try to preempt if the target thread is holding any tokens.
989 * We could try to acquire the tokens but this case is so rare there
990 * is no need to support it.
41a01a4d 991 */
77912481
MD
992 KKASSERT(gd->gd_spinlock_rd == NULL);
993 KKASSERT(gd->gd_spinlocks_wr == 0);
994
3b998fa9 995 if (TD_TOKS_HELD(ntd)) {
d3d1cbc8
MD
996 ++preempt_miss;
997 need_lwkt_resched();
998 return;
999 }
26a0694b
MD
1000 if (td == ntd || ((td->td_flags | ntd->td_flags) & TDF_PREEMPT_LOCK)) {
1001 ++preempt_weird;
8ec60c3f 1002 need_lwkt_resched();
26a0694b
MD
1003 return;
1004 }
1005 if (ntd->td_preempted) {
4b5f931b 1006 ++preempt_hit;
8ec60c3f 1007 need_lwkt_resched();
26a0694b 1008 return;
b68b7282 1009 }
8a8d5d85 1010#ifdef SMP
a2a5ad0d
MD
1011 /*
1012 * note: an interrupt might have occured just as we were transitioning
71ef2f5c
MD
1013 * to or from the MP lock. In this case td_mpcount will be pre-disposed
1014 * (non-zero) but not actually synchronized with the actual state of the
1015 * lock. We can use it to imply an MP lock requirement for the
1016 * preemption but we cannot use it to test whether we hold the MP lock
1017 * or not.
a2a5ad0d 1018 */
96728c05 1019 savecnt = td->td_mpcount;
c5724852 1020 mpheld = MP_LOCK_HELD(gd);
8a8d5d85
MD
1021 ntd->td_mpcount += td->td_mpcount;
1022 if (mpheld == 0 && ntd->td_mpcount && !cpu_try_mplock()) {
1023 ntd->td_mpcount -= td->td_mpcount;
1024 ++preempt_miss;
8ec60c3f 1025 need_lwkt_resched();
8a8d5d85
MD
1026 return;
1027 }
1028#endif
26a0694b 1029
8ec60c3f
MD
1030 /*
1031 * Since we are able to preempt the current thread, there is no need to
1032 * call need_lwkt_resched().
1033 */
26a0694b
MD
1034 ++preempt_hit;
1035 ntd->td_preempted = td;
1036 td->td_flags |= TDF_PREEMPT_LOCK;
a1f0fb66 1037 KTR_LOG(ctxsw_pre, gd->gd_cpuid, ntd);
26a0694b 1038 td->td_switch(ntd);
b9eb1c19 1039
26a0694b 1040 KKASSERT(ntd->td_preempted && (td->td_flags & TDF_PREEMPT_DONE));
96728c05
MD
1041#ifdef SMP
1042 KKASSERT(savecnt == td->td_mpcount);
c5724852 1043 mpheld = MP_LOCK_HELD(gd);
71ef2f5c 1044 if (mpheld && td->td_mpcount == 0)
c5724852 1045 cpu_rel_mplock(gd->gd_cpuid);
71ef2f5c 1046 else if (mpheld == 0 && td->td_mpcount)
96728c05
MD
1047 panic("lwkt_preempt(): MP lock was not held through");
1048#endif
26a0694b
MD
1049 ntd->td_preempted = NULL;
1050 td->td_flags &= ~(TDF_PREEMPT_LOCK|TDF_PREEMPT_DONE);
b68b7282
MD
1051}
1052
1053/*
faaeffac 1054 * Conditionally call splz() if gd_reqflags indicates work is pending.
4a28fe22
MD
1055 * This will work inside a critical section but not inside a hard code
1056 * section.
ef0fdad1 1057 *
f1d1c3fa
MD
1058 * (self contained on a per cpu basis)
1059 */
1060void
faaeffac 1061splz_check(void)
f1d1c3fa 1062{
7966cb69
MD
1063 globaldata_t gd = mycpu;
1064 thread_t td = gd->gd_curthread;
ef0fdad1 1065
4a28fe22
MD
1066 if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) &&
1067 gd->gd_intr_nesting_level == 0 &&
1068 td->td_nest_count < 2)
1069 {
f1d1c3fa 1070 splz();
4a28fe22
MD
1071 }
1072}
1073
1074/*
1075 * This version is integrated into crit_exit, reqflags has already
1076 * been tested but td_critcount has not.
1077 *
1078 * We only want to execute the splz() on the 1->0 transition of
1079 * critcount and not in a hard code section or if too deeply nested.
1080 */
1081void
1082lwkt_maybe_splz(thread_t td)
1083{
1084 globaldata_t gd = td->td_gd;
1085
1086 if (td->td_critcount == 0 &&
1087 gd->gd_intr_nesting_level == 0 &&
1088 td->td_nest_count < 2)
1089 {
1090 splz();
1091 }
f1d1c3fa
MD
1092}
1093
8ad65e08 1094/*
f9235b6d
MD
1095 * This function is used to negotiate a passive release of the current
1096 * process/lwp designation with the user scheduler, allowing the user
1097 * scheduler to schedule another user thread. The related kernel thread
1098 * (curthread) continues running in the released state.
8ad65e08
MD
1099 */
1100void
f9235b6d 1101lwkt_passive_release(struct thread *td)
8ad65e08 1102{
f9235b6d
MD
1103 struct lwp *lp = td->td_lwp;
1104
1105 td->td_release = NULL;
1106 lwkt_setpri_self(TDPRI_KERN_USER);
1107 lp->lwp_proc->p_usched->release_curproc(lp);
f1d1c3fa
MD
1108}
1109
f9235b6d 1110
f1d1c3fa 1111/*
f9235b6d
MD
1112 * This implements a normal yield. This routine is virtually a nop if
1113 * there is nothing to yield to but it will always run any pending interrupts
1114 * if called from a critical section.
1115 *
1116 * This yield is designed for kernel threads without a user context.
1117 *
1118 * (self contained on a per cpu basis)
3824f392
MD
1119 */
1120void
f9235b6d 1121lwkt_yield(void)
3824f392 1122{
f9235b6d
MD
1123 globaldata_t gd = mycpu;
1124 thread_t td = gd->gd_curthread;
1125 thread_t xtd;
3824f392 1126
f9235b6d
MD
1127 if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) && td->td_nest_count < 2)
1128 splz();
1129 if (td->td_fairq_accum < 0) {
1130 lwkt_schedule_self(curthread);
1131 lwkt_switch();
1132 } else {
1133 xtd = TAILQ_FIRST(&gd->gd_tdrunq);
1134 if (xtd && xtd->td_pri > td->td_pri) {
1135 lwkt_schedule_self(curthread);
1136 lwkt_switch();
1137 }
1138 }
3824f392
MD
1139}
1140
1141/*
f9235b6d
MD
1142 * This yield is designed for kernel threads with a user context.
1143 *
1144 * The kernel acting on behalf of the user is potentially cpu-bound,
1145 * this function will efficiently allow other threads to run and also
1146 * switch to other processes by releasing.
3824f392
MD
1147 *
1148 * The lwkt_user_yield() function is designed to have very low overhead
1149 * if no yield is determined to be needed.
1150 */
1151void
1152lwkt_user_yield(void)
1153{
f9235b6d
MD
1154 globaldata_t gd = mycpu;
1155 thread_t td = gd->gd_curthread;
1156
1157 /*
1158 * Always run any pending interrupts in case we are in a critical
1159 * section.
1160 */
1161 if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) && td->td_nest_count < 2)
1162 splz();
3824f392
MD
1163
1164#ifdef SMP
1165 /*
1166 * XXX SEVERE TEMPORARY HACK. A cpu-bound operation running in the
1167 * kernel can prevent other cpus from servicing interrupt threads
1168 * which still require the MP lock (which is a lot of them). This
1169 * has a chaining effect since if the interrupt is blocked, so is
1170 * the event, so normal scheduling will not pick up on the problem.
1171 */
c5724852 1172 if (cpu_contention_mask && td->td_mpcount) {
684a93c4 1173 yield_mplock(td);
3824f392
MD
1174 }
1175#endif
1176
1177 /*
f9235b6d
MD
1178 * Switch (which forces a release) if another kernel thread needs
1179 * the cpu, if userland wants us to resched, or if our kernel
1180 * quantum has run out.
3824f392 1181 */
f9235b6d
MD
1182 if (lwkt_resched_wanted() ||
1183 user_resched_wanted() ||
1184 td->td_fairq_accum < 0)
1185 {
3824f392 1186 lwkt_switch();
3824f392
MD
1187 }
1188
f9235b6d 1189#if 0
3824f392 1190 /*
f9235b6d
MD
1191 * Reacquire the current process if we are released.
1192 *
1193 * XXX not implemented atm. The kernel may be holding locks and such,
1194 * so we want the thread to continue to receive cpu.
3824f392 1195 */
f9235b6d
MD
1196 if (td->td_release == NULL && lp) {
1197 lp->lwp_proc->p_usched->acquire_curproc(lp);
1198 td->td_release = lwkt_passive_release;
1199 lwkt_setpri_self(TDPRI_USER_NORM);
3824f392 1200 }
f9235b6d 1201#endif
b9eb1c19
MD
1202}
1203
1204/*
f1d1c3fa
MD
1205 * Generic schedule. Possibly schedule threads belonging to other cpus and
1206 * deal with threads that might be blocked on a wait queue.
1207 *
0a3f9b47
MD
1208 * We have a little helper inline function which does additional work after
1209 * the thread has been enqueued, including dealing with preemption and
1210 * setting need_lwkt_resched() (which prevents the kernel from returning
1211 * to userland until it has processed higher priority threads).
6330a558
MD
1212 *
1213 * It is possible for this routine to be called after a failed _enqueue
1214 * (due to the target thread migrating, sleeping, or otherwise blocked).
1215 * We have to check that the thread is actually on the run queue!
361d01dd
MD
1216 *
1217 * reschedok is an optimized constant propagated from lwkt_schedule() or
1218 * lwkt_schedule_noresched(). By default it is non-zero, causing a
1219 * reschedule to be requested if the target thread has a higher priority.
1220 * The port messaging code will set MSG_NORESCHED and cause reschedok to
1221 * be 0, prevented undesired reschedules.
8ad65e08 1222 */
0a3f9b47
MD
1223static __inline
1224void
f9235b6d 1225_lwkt_schedule_post(globaldata_t gd, thread_t ntd, int ccount, int reschedok)
0a3f9b47 1226{
b9eb1c19 1227 thread_t otd;
c730be20 1228
6330a558 1229 if (ntd->td_flags & TDF_RUNQ) {
361d01dd 1230 if (ntd->td_preemptable && reschedok) {
f9235b6d 1231 ntd->td_preemptable(ntd, ccount); /* YYY +token */
361d01dd 1232 } else if (reschedok) {
b9eb1c19 1233 otd = curthread;
f9235b6d 1234 if (ntd->td_pri > otd->td_pri)
c730be20 1235 need_lwkt_resched();
6330a558 1236 }
f9235b6d
MD
1237
1238 /*
1239 * Give the thread a little fair share scheduler bump if it
1240 * has been asleep for a while. This is primarily to avoid
1241 * a degenerate case for interrupt threads where accumulator
1242 * crosses into negative territory unnecessarily.
1243 */
1244 if (ntd->td_fairq_lticks != ticks) {
1245 ntd->td_fairq_lticks = ticks;
1246 ntd->td_fairq_accum += gd->gd_fairq_total_pri;
1247 if (ntd->td_fairq_accum > TDFAIRQ_MAX(gd))
1248 ntd->td_fairq_accum = TDFAIRQ_MAX(gd);
1249 }
0a3f9b47
MD
1250 }
1251}
1252
361d01dd 1253static __inline
8ad65e08 1254void
361d01dd 1255_lwkt_schedule(thread_t td, int reschedok)
8ad65e08 1256{
37af14fe
MD
1257 globaldata_t mygd = mycpu;
1258
41a01a4d 1259 KASSERT(td != &td->td_gd->gd_idlethread, ("lwkt_schedule(): scheduling gd_idlethread is illegal!"));
37af14fe 1260 crit_enter_gd(mygd);
9388413d 1261 KKASSERT(td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0);
37af14fe 1262 if (td == mygd->gd_curthread) {
f1d1c3fa
MD
1263 _lwkt_enqueue(td);
1264 } else {
f1d1c3fa 1265 /*
7cd8d145
MD
1266 * If we own the thread, there is no race (since we are in a
1267 * critical section). If we do not own the thread there might
1268 * be a race but the target cpu will deal with it.
f1d1c3fa 1269 */
0f7a3396 1270#ifdef SMP
7cd8d145 1271 if (td->td_gd == mygd) {
9d265729 1272 _lwkt_enqueue(td);
f9235b6d 1273 _lwkt_schedule_post(mygd, td, 1, reschedok);
f1d1c3fa 1274 } else {
e381e77c 1275 lwkt_send_ipiq3(td->td_gd, lwkt_schedule_remote, td, 0);
7cd8d145 1276 }
0f7a3396 1277#else
7cd8d145 1278 _lwkt_enqueue(td);
f9235b6d 1279 _lwkt_schedule_post(mygd, td, 1, reschedok);
0f7a3396 1280#endif
8ad65e08 1281 }
37af14fe 1282 crit_exit_gd(mygd);
8ad65e08
MD
1283}
1284
361d01dd
MD
1285void
1286lwkt_schedule(thread_t td)
1287{
1288 _lwkt_schedule(td, 1);
1289}
1290
1291void
1292lwkt_schedule_noresched(thread_t td)
1293{
1294 _lwkt_schedule(td, 0);
1295}
1296
88ebb169
SW
1297#ifdef SMP
1298
e381e77c
MD
1299/*
1300 * When scheduled remotely if frame != NULL the IPIQ is being
1301 * run via doreti or an interrupt then preemption can be allowed.
1302 *
1303 * To allow preemption we have to drop the critical section so only
1304 * one is present in _lwkt_schedule_post.
1305 */
1306static void
1307lwkt_schedule_remote(void *arg, int arg2, struct intrframe *frame)
1308{
1309 thread_t td = curthread;
1310 thread_t ntd = arg;
1311
1312 if (frame && ntd->td_preemptable) {
1313 crit_exit_noyield(td);
1314 _lwkt_schedule(ntd, 1);
1315 crit_enter_quick(td);
1316 } else {
1317 _lwkt_schedule(ntd, 1);
1318 }
1319}
1320
d9eea1a5 1321/*
52eedfb5
MD
1322 * Thread migration using a 'Pull' method. The thread may or may not be
1323 * the current thread. It MUST be descheduled and in a stable state.
1324 * lwkt_giveaway() must be called on the cpu owning the thread.
1325 *
1326 * At any point after lwkt_giveaway() is called, the target cpu may
1327 * 'pull' the thread by calling lwkt_acquire().
1328 *
ae8e83e6
MD
1329 * We have to make sure the thread is not sitting on a per-cpu tsleep
1330 * queue or it will blow up when it moves to another cpu.
1331 *
52eedfb5 1332 * MPSAFE - must be called under very specific conditions.
d9eea1a5 1333 */
a2a5ad0d 1334void
52eedfb5
MD
1335lwkt_giveaway(thread_t td)
1336{
3b4192fb 1337 globaldata_t gd = mycpu;
52eedfb5 1338
3b4192fb
MD
1339 crit_enter_gd(gd);
1340 if (td->td_flags & TDF_TSLEEPQ)
1341 tsleep_remove(td);
1342 KKASSERT(td->td_gd == gd);
1343 TAILQ_REMOVE(&gd->gd_tdallq, td, td_allq);
1344 td->td_flags |= TDF_MIGRATING;
1345 crit_exit_gd(gd);
52eedfb5
MD
1346}
1347
1348void
a2a5ad0d
MD
1349lwkt_acquire(thread_t td)
1350{
37af14fe
MD
1351 globaldata_t gd;
1352 globaldata_t mygd;
a2a5ad0d 1353
52eedfb5 1354 KKASSERT(td->td_flags & TDF_MIGRATING);
a2a5ad0d 1355 gd = td->td_gd;
37af14fe 1356 mygd = mycpu;
52eedfb5 1357 if (gd != mycpu) {
35238fa5 1358 cpu_lfence();
52eedfb5 1359 KKASSERT((td->td_flags & TDF_RUNQ) == 0);
37af14fe 1360 crit_enter_gd(mygd);
df910c23
MD
1361 while (td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK)) {
1362#ifdef SMP
1363 lwkt_process_ipiq();
1364#endif
52eedfb5 1365 cpu_lfence();
df910c23 1366 }
37af14fe 1367 td->td_gd = mygd;
52eedfb5
MD
1368 TAILQ_INSERT_TAIL(&mygd->gd_tdallq, td, td_allq);
1369 td->td_flags &= ~TDF_MIGRATING;
1370 crit_exit_gd(mygd);
1371 } else {
1372 crit_enter_gd(mygd);
1373 TAILQ_INSERT_TAIL(&mygd->gd_tdallq, td, td_allq);
1374 td->td_flags &= ~TDF_MIGRATING;
37af14fe 1375 crit_exit_gd(mygd);
a2a5ad0d
MD
1376 }
1377}
1378
52eedfb5
MD
1379#endif
1380
8ad65e08 1381/*
f1d1c3fa
MD
1382 * Generic deschedule. Descheduling threads other then your own should be
1383 * done only in carefully controlled circumstances. Descheduling is
1384 * asynchronous.
1385 *
1386 * This function may block if the cpu has run out of messages.
8ad65e08
MD
1387 */
1388void
1389lwkt_deschedule(thread_t td)
1390{
f1d1c3fa 1391 crit_enter();
b8a98473 1392#ifdef SMP
f1d1c3fa
MD
1393 if (td == curthread) {
1394 _lwkt_dequeue(td);
1395 } else {
a72187e9 1396 if (td->td_gd == mycpu) {
f1d1c3fa
MD
1397 _lwkt_dequeue(td);
1398 } else {
b8a98473 1399 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)lwkt_deschedule, td);
f1d1c3fa
MD
1400 }
1401 }
b8a98473
MD
1402#else
1403 _lwkt_dequeue(td);
1404#endif
f1d1c3fa
MD
1405 crit_exit();
1406}
1407
1408/*
4b5f931b
MD
1409 * Set the target thread's priority. This routine does not automatically
1410 * switch to a higher priority thread, LWKT threads are not designed for
1411 * continuous priority changes. Yield if you want to switch.
4b5f931b
MD
1412 */
1413void
1414lwkt_setpri(thread_t td, int pri)
1415{
a72187e9 1416 KKASSERT(td->td_gd == mycpu);
f9235b6d
MD
1417 if (td->td_pri != pri) {
1418 KKASSERT(pri >= 0);
1419 crit_enter();
1420 if (td->td_flags & TDF_RUNQ) {
1421 _lwkt_dequeue(td);
1422 td->td_pri = pri;
1423 _lwkt_enqueue(td);
1424 } else {
1425 td->td_pri = pri;
1426 }
1427 crit_exit();
26a0694b 1428 }
26a0694b
MD
1429}
1430
03bd0a5e
MD
1431/*
1432 * Set the initial priority for a thread prior to it being scheduled for
1433 * the first time. The thread MUST NOT be scheduled before or during
1434 * this call. The thread may be assigned to a cpu other then the current
1435 * cpu.
1436 *
1437 * Typically used after a thread has been created with TDF_STOPPREQ,
1438 * and before the thread is initially scheduled.
1439 */
1440void
1441lwkt_setpri_initial(thread_t td, int pri)
1442{
1443 KKASSERT(pri >= 0);
1444 KKASSERT((td->td_flags & TDF_RUNQ) == 0);
f9235b6d 1445 td->td_pri = pri;
03bd0a5e
MD
1446}
1447
26a0694b
MD
1448void
1449lwkt_setpri_self(int pri)
1450{
1451 thread_t td = curthread;
1452
4b5f931b
MD
1453 KKASSERT(pri >= 0 && pri <= TDPRI_MAX);
1454 crit_enter();
1455 if (td->td_flags & TDF_RUNQ) {
1456 _lwkt_dequeue(td);
f9235b6d 1457 td->td_pri = pri;
4b5f931b
MD
1458 _lwkt_enqueue(td);
1459 } else {
f9235b6d 1460 td->td_pri = pri;
4b5f931b
MD
1461 }
1462 crit_exit();
1463}
1464
5d21b981 1465/*
f9235b6d
MD
1466 * 1/hz tick (typically 10ms) x TDFAIRQ_SCALE (typ 8) = 80ms full cycle.
1467 *
1468 * Example: two competing threads, same priority N. decrement by (2*N)
1469 * increment by N*8, each thread will get 4 ticks.
1470 */
1471void
1472lwkt_fairq_schedulerclock(thread_t td)
1473{
1474 if (fairq_enable) {
1475 while (td) {
1476 if (td != &td->td_gd->gd_idlethread) {
1477 td->td_fairq_accum -= td->td_gd->gd_fairq_total_pri;
1478 if (td->td_fairq_accum < -TDFAIRQ_MAX(td->td_gd))
1479 td->td_fairq_accum = -TDFAIRQ_MAX(td->td_gd);
1480 if (td->td_fairq_accum < 0)
1481 need_lwkt_resched();
1482 td->td_fairq_lticks = ticks;
1483 }
1484 td = td->td_preempted;
1485 }
1486 }
1487}
1488
1489static void
1490lwkt_fairq_accumulate(globaldata_t gd, thread_t td)
1491{
1492 td->td_fairq_accum += td->td_pri * TDFAIRQ_SCALE;
1493 if (td->td_fairq_accum > TDFAIRQ_MAX(td->td_gd))
1494 td->td_fairq_accum = TDFAIRQ_MAX(td->td_gd);
1495}
1496
1497/*
52eedfb5
MD
1498 * Migrate the current thread to the specified cpu.
1499 *
1500 * This is accomplished by descheduling ourselves from the current cpu,
1501 * moving our thread to the tdallq of the target cpu, IPI messaging the
1502 * target cpu, and switching out. TDF_MIGRATING prevents scheduling
1503 * races while the thread is being migrated.
ae8e83e6
MD
1504 *
1505 * We must be sure to remove ourselves from the current cpu's tsleepq
1506 * before potentially moving to another queue. The thread can be on
1507 * a tsleepq due to a left-over tsleep_interlock().
5d21b981 1508 */
3d28ff59 1509#ifdef SMP
5d21b981 1510static void lwkt_setcpu_remote(void *arg);
3d28ff59 1511#endif
5d21b981
MD
1512
1513void
1514lwkt_setcpu_self(globaldata_t rgd)
1515{
1516#ifdef SMP
1517 thread_t td = curthread;
1518
1519 if (td->td_gd != rgd) {
1520 crit_enter_quick(td);
ae8e83e6 1521 if (td->td_flags & TDF_TSLEEPQ)
3b4192fb 1522 tsleep_remove(td);
5d21b981
MD
1523 td->td_flags |= TDF_MIGRATING;
1524 lwkt_deschedule_self(td);
52eedfb5 1525 TAILQ_REMOVE(&td->td_gd->gd_tdallq, td, td_allq);
b8a98473 1526 lwkt_send_ipiq(rgd, (ipifunc1_t)lwkt_setcpu_remote, td);
5d21b981
MD
1527 lwkt_switch();
1528 /* we are now on the target cpu */
52eedfb5 1529 TAILQ_INSERT_TAIL(&rgd->gd_tdallq, td, td_allq);
5d21b981
MD
1530 crit_exit_quick(td);
1531 }
1532#endif
1533}
1534
ecdefdda
MD
1535void
1536lwkt_migratecpu(int cpuid)
1537{
1538#ifdef SMP
1539 globaldata_t rgd;
1540
1541 rgd = globaldata_find(cpuid);
1542 lwkt_setcpu_self(rgd);
1543#endif
1544}
1545
5d21b981
MD
1546/*
1547 * Remote IPI for cpu migration (called while in a critical section so we
1548 * do not have to enter another one). The thread has already been moved to
1549 * our cpu's allq, but we must wait for the thread to be completely switched
1550 * out on the originating cpu before we schedule it on ours or the stack
1551 * state may be corrupt. We clear TDF_MIGRATING after flushing the GD
1552 * change to main memory.
1553 *
1554 * XXX The use of TDF_MIGRATING might not be sufficient to avoid races
1555 * against wakeups. It is best if this interface is used only when there
1556 * are no pending events that might try to schedule the thread.
1557 */
3d28ff59 1558#ifdef SMP
5d21b981
MD
1559static void
1560lwkt_setcpu_remote(void *arg)
1561{
1562 thread_t td = arg;
1563 globaldata_t gd = mycpu;
1564
df910c23
MD
1565 while (td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK)) {
1566#ifdef SMP
1567 lwkt_process_ipiq();
1568#endif
35238fa5 1569 cpu_lfence();
df910c23 1570 }
5d21b981 1571 td->td_gd = gd;
35238fa5 1572 cpu_sfence();
5d21b981 1573 td->td_flags &= ~TDF_MIGRATING;
9388413d 1574 KKASSERT(td->td_lwp == NULL || (td->td_lwp->lwp_flag & LWP_ONRUNQ) == 0);
5d21b981
MD
1575 _lwkt_enqueue(td);
1576}
3d28ff59 1577#endif
5d21b981 1578
553ea3c8 1579struct lwp *
4b5f931b
MD
1580lwkt_preempted_proc(void)
1581{
73e4f7b9 1582 thread_t td = curthread;
4b5f931b
MD
1583 while (td->td_preempted)
1584 td = td->td_preempted;
553ea3c8 1585 return(td->td_lwp);
4b5f931b
MD
1586}
1587
4b5f931b 1588/*
99df837e
MD
1589 * Create a kernel process/thread/whatever. It shares it's address space
1590 * with proc0 - ie: kernel only.
1591 *
365fa13f
MD
1592 * NOTE! By default new threads are created with the MP lock held. A
1593 * thread which does not require the MP lock should release it by calling
1594 * rel_mplock() at the start of the new thread.
99df837e
MD
1595 */
1596int
c9e9fb21
MD
1597lwkt_create(void (*func)(void *), void *arg, struct thread **tdp,
1598 thread_t template, int tdflags, int cpu, const char *fmt, ...)
99df837e 1599{
73e4f7b9 1600 thread_t td;
e2565a42 1601 __va_list ap;
99df837e 1602
d3d32139 1603 td = lwkt_alloc_thread(template, LWKT_THREAD_STACK, cpu,
dbcd0c9b 1604 tdflags);
a2a5ad0d
MD
1605 if (tdp)
1606 *tdp = td;
709799ea 1607 cpu_set_thread_handler(td, lwkt_exit, func, arg);
99df837e
MD
1608
1609 /*
1610 * Set up arg0 for 'ps' etc
1611 */
e2565a42 1612 __va_start(ap, fmt);
379210cb 1613 kvsnprintf(td->td_comm, sizeof(td->td_comm), fmt, ap);
e2565a42 1614 __va_end(ap);
99df837e
MD
1615
1616 /*
1617 * Schedule the thread to run
1618 */
ef0fdad1
MD
1619 if ((td->td_flags & TDF_STOPREQ) == 0)
1620 lwkt_schedule(td);
1621 else
1622 td->td_flags &= ~TDF_STOPREQ;
99df837e
MD
1623 return 0;
1624}
1625
1626/*
1627 * Destroy an LWKT thread. Warning! This function is not called when
1628 * a process exits, cpu_proc_exit() directly calls cpu_thread_exit() and
1629 * uses a different reaping mechanism.
1630 */
1631void
1632lwkt_exit(void)
1633{
1634 thread_t td = curthread;
c070746a 1635 thread_t std;
8826f33a 1636 globaldata_t gd;
99df837e
MD
1637
1638 if (td->td_flags & TDF_VERBOSE)
6ea70f76 1639 kprintf("kthread %p %s has exited\n", td, td->td_comm);
f6bf3af1 1640 caps_exit(td);
c070746a
MD
1641
1642 /*
1643 * Get us into a critical section to interlock gd_freetd and loop
1644 * until we can get it freed.
1645 *
1646 * We have to cache the current td in gd_freetd because objcache_put()ing
1647 * it would rip it out from under us while our thread is still active.
1648 */
1649 gd = mycpu;
37af14fe 1650 crit_enter_quick(td);
c070746a
MD
1651 while ((std = gd->gd_freetd) != NULL) {
1652 gd->gd_freetd = NULL;
1653 objcache_put(thread_cache, std);
1654 }
3b4192fb
MD
1655
1656 /*
1657 * Remove thread resources from kernel lists and deschedule us for
1658 * the last time.
1659 */
1660 if (td->td_flags & TDF_TSLEEPQ)
1661 tsleep_remove(td);
79eae878 1662 biosched_done(td);
f8abf63c 1663 dsched_exit_thread(td);
37af14fe 1664 lwkt_deschedule_self(td);
e56e4dea 1665 lwkt_remove_tdallq(td);
c070746a
MD
1666 if (td->td_flags & TDF_ALLOCATED_THREAD)
1667 gd->gd_freetd = td;
99df837e
MD
1668 cpu_thread_exit();
1669}
1670
e56e4dea
MD
1671void
1672lwkt_remove_tdallq(thread_t td)
1673{
1674 KKASSERT(td->td_gd == mycpu);
1675 TAILQ_REMOVE(&td->td_gd->gd_tdallq, td, td_allq);
1676}
1677
9cf43f91
MD
1678/*
1679 * Code reduction and branch prediction improvements. Call/return
1680 * overhead on modern cpus often degenerates into 0 cycles due to
1681 * the cpu's branch prediction hardware and return pc cache. We
1682 * can take advantage of this by not inlining medium-complexity
1683 * functions and we can also reduce the branch prediction impact
1684 * by collapsing perfectly predictable branches into a single
1685 * procedure instead of duplicating it.
1686 *
1687 * Is any of this noticeable? Probably not, so I'll take the
1688 * smaller code size.
1689 */
1690void
b6468f56 1691crit_exit_wrapper(__DEBUG_CRIT_ARG__)
9cf43f91 1692{
b6468f56 1693 _crit_exit(mycpu __DEBUG_CRIT_PASS_ARG__);
9cf43f91
MD
1694}
1695
2d93b37a
MD
1696void
1697crit_panic(void)
1698{
1699 thread_t td = curthread;
850634cc 1700 int lcrit = td->td_critcount;
2d93b37a 1701
850634cc
AH
1702 td->td_critcount = 0;
1703 panic("td_critcount is/would-go negative! %p %d", td, lcrit);
4a28fe22 1704 /* NOT REACHED */
2d93b37a
MD
1705}
1706
d165e668
MD
1707#ifdef SMP
1708
bd8015ca
MD
1709/*
1710 * Called from debugger/panic on cpus which have been stopped. We must still
1711 * process the IPIQ while stopped, even if we were stopped while in a critical
1712 * section (XXX).
1713 *
1714 * If we are dumping also try to process any pending interrupts. This may
1715 * or may not work depending on the state of the cpu at the point it was
1716 * stopped.
1717 */
1718void
1719lwkt_smp_stopped(void)
1720{
1721 globaldata_t gd = mycpu;
1722
1723 crit_enter_gd(gd);
1724 if (dumping) {
1725 lwkt_process_ipiq();
1726 splz();
1727 } else {
1728 lwkt_process_ipiq();
1729 }
1730 crit_exit_gd(gd);
1731}
1732
d165e668 1733#endif