2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
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18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
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
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31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * $DragonFly: src/sys/kern/lwkt_token.c,v 1.10 2004/09/21 18:46:00 joerg Exp $
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/kernel.h>
43 #include <sys/rtprio.h>
44 #include <sys/queue.h>
45 #include <sys/thread2.h>
46 #include <sys/sysctl.h>
47 #include <sys/kthread.h>
48 #include <machine/cpu.h>
53 #include <vm/vm_param.h>
54 #include <vm/vm_kern.h>
55 #include <vm/vm_object.h>
56 #include <vm/vm_page.h>
57 #include <vm/vm_map.h>
58 #include <vm/vm_pager.h>
59 #include <vm/vm_extern.h>
60 #include <vm/vm_zone.h>
62 #include <machine/stdarg.h>
63 #include <machine/ipl.h>
64 #include <machine/smp.h>
66 #define THREAD_STACK (UPAGES * PAGE_SIZE)
70 #include <sys/stdint.h>
71 #include <libcaps/thread.h>
72 #include <sys/thread.h>
73 #include <sys/msgport.h>
74 #include <sys/errno.h>
75 #include <libcaps/globaldata.h>
76 #include <machine/cpufunc.h>
77 #include <sys/thread2.h>
78 #include <sys/msgport2.h>
82 #include <machine/lock.h>
83 #include <machine/cpu.h>
87 #define MAKE_TOKENS_SPIN
88 /* #define MAKE_TOKENS_YIELD */
90 #ifndef LWKT_NUM_POOL_TOKENS
91 #define LWKT_NUM_POOL_TOKENS 1024 /* power of 2 */
93 #define LWKT_MASK_POOL_TOKENS (LWKT_NUM_POOL_TOKENS - 1)
96 static int token_debug = 0;
99 static lwkt_token pool_tokens[LWKT_NUM_POOL_TOKENS];
104 SYSCTL_INT(_lwkt, OID_AUTO, token_debug, CTLFLAG_RW, &token_debug, 0, "");
112 * Determine if we own all the tokens in the token reference list.
113 * Return 1 on success, 0 on failure.
115 * As a side effect, queue requests for tokens we want which are owned
116 * by other cpus. The magic number is used to communicate when the
117 * target cpu has processed the request. Note, however, that the
118 * target cpu may not be able to assign the token to us which is why
119 * the scheduler must spin.
122 lwkt_chktokens(thread_t td)
124 globaldata_t gd = td->td_gd; /* mycpu */
130 for (refs = td->td_toks; refs; refs = refs->tr_next) {
132 if ((dgd = tok->t_cpu) != gd) {
137 * Queue a request to the target cpu, exit the loop early if
138 * we are unable to queue the IPI message. The magic number
139 * flags whether we have a pending ipi request queued or not.
141 if (refs->tr_magic == LWKT_TOKREF_MAGIC1) {
142 refs->tr_magic = LWKT_TOKREF_MAGIC2; /* MP synched slowreq*/
144 tok->t_reqcpu = gd; /* MP unsynchronized 'fast' req */
145 if (lwkt_send_ipiq_passive(dgd, lwkt_reqtoken_remote, refs)) {
147 refs->tr_magic = LWKT_TOKREF_MAGIC1;
159 * Check if we already own the token. Return 1 on success, 0 on failure.
162 lwkt_havetoken(lwkt_token_t tok)
164 globaldata_t gd = mycpu;
165 thread_t td = gd->gd_curthread;
168 for (ref = td->td_toks; ref; ref = ref->tr_next) {
169 if (ref->tr_tok == tok)
176 lwkt_havetokref(lwkt_tokref_t xref)
178 globaldata_t gd = mycpu;
179 thread_t td = gd->gd_curthread;
182 for (ref = td->td_toks; ref; ref = ref->tr_next) {
192 * Returns 1 if it is ok to give a token away, 0 if it is not.
195 lwkt_oktogiveaway_token(lwkt_token_t tok)
197 globaldata_t gd = mycpu;
201 for (td = gd->gd_curthread; td; td = td->td_preempted) {
202 for (ref = td->td_toks; ref; ref = ref->tr_next) {
203 if (ref->tr_tok == tok)
213 * Acquire a serializing token
218 _lwkt_gettokref(lwkt_tokref_t ref)
224 gd = mycpu; /* our cpu */
225 KKASSERT(ref->tr_magic == LWKT_TOKREF_MAGIC1);
226 td = gd->gd_curthread; /* our thread */
229 * Link the request into our thread's list. This interlocks against
230 * remote requests from other cpus and prevents the token from being
231 * given away if our cpu already owns it. This also allows us to
232 * avoid using a critical section.
234 ref->tr_next = td->td_toks;
235 cpu_mb1(); /* order memory / we can be interrupted */
239 * If our cpu does not own the token then let the scheduler deal with
240 * it. We are guarenteed to own the tokens on our thread's token
241 * list when we are switched back in.
243 * Otherwise make sure the token is not held by a thread we are
244 * preempting. If it is, let the scheduler deal with it.
248 if (tok->t_cpu != gd) {
250 * Temporarily operate on tokens synchronously. We have to fix
251 * a number of interlocks and especially the softupdates code to
252 * be able to properly yield. ZZZ
254 #if defined(MAKE_TOKENS_SPIN)
257 while (lwkt_chktokens(td) == 0) {
259 lwkt_drain_token_requests();
262 printf("CHKTOKEN loop %d\n", gd->gd_cpuid);
270 #elif defined(MAKE_TOKENS_YIELD)
273 #error MAKE_TOKENS_XXX ?
275 KKASSERT(tok->t_cpu == gd);
276 } else /* NOTE CONDITIONAL */
278 if (td->td_preempted) {
279 while ((td = td->td_preempted) != NULL) {
281 for (scan = td->td_toks; scan; scan = scan->tr_next) {
282 if (scan->tr_tok == tok) {
284 KKASSERT(tok->t_cpu == gd);
291 /* 'td' variable no longer valid due to preempt loop above */
296 * Attempt to acquire a serializing token
300 _lwkt_trytokref(lwkt_tokref_t ref)
306 gd = mycpu; /* our cpu */
307 KKASSERT(ref->tr_magic == LWKT_TOKREF_MAGIC1);
308 td = gd->gd_curthread; /* our thread */
311 * Link the request into our thread's list. This interlocks against
312 * remote requests from other cpus and prevents the token from being
313 * given away if our cpu already owns it. This also allows us to
314 * avoid using a critical section.
316 ref->tr_next = td->td_toks;
317 cpu_mb1(); /* order memory / we can be interrupted */
321 * If our cpu does not own the token then stop now.
323 * Otherwise make sure the token is not held by a thread we are
324 * preempting. If it is, stop.
328 if (tok->t_cpu != gd) {
329 td->td_toks = ref->tr_next; /* remove ref */
331 } else /* NOTE CONDITIONAL */
333 if (td->td_preempted) {
334 while ((td = td->td_preempted) != NULL) {
336 for (scan = td->td_toks; scan; scan = scan->tr_next) {
337 if (scan->tr_tok == tok) {
338 td = gd->gd_curthread; /* our thread */
339 td->td_toks = ref->tr_next; /* remove ref */
345 /* 'td' variable no longer valid */
350 lwkt_gettoken(lwkt_tokref_t ref, lwkt_token_t tok)
352 lwkt_tokref_init(ref, tok);
353 _lwkt_gettokref(ref);
357 lwkt_gettokref(lwkt_tokref_t ref)
359 _lwkt_gettokref(ref);
363 lwkt_trytoken(lwkt_tokref_t ref, lwkt_token_t tok)
365 lwkt_tokref_init(ref, tok);
366 return(_lwkt_trytokref(ref));
370 lwkt_trytokref(lwkt_tokref_t ref)
372 return(_lwkt_trytokref(ref));
376 * Release a serializing token
379 lwkt_reltoken(lwkt_tokref *_ref)
388 * Guard check and stack check (if in the same stack page). We must
389 * also wait for any action pending on remote cpus which we do by
390 * checking the magic number and yielding in a loop.
394 if ((((intptr_t)ref ^ (intptr_t)&_ref) && ~(intptr_t)PAGE_MASK) == 0)
395 KKASSERT((char *)ref > (char *)&_ref);
396 KKASSERT(ref->tr_magic == LWKT_TOKREF_MAGIC1 ||
397 ref->tr_magic == LWKT_TOKREF_MAGIC2);
400 * Locate and unlink the token. Interlock with the token's cpureq
401 * to give the token away before we release it from our thread list,
402 * which allows us to avoid using a critical section.
405 td = gd->gd_curthread;
406 for (pref = &td->td_toks; (ref = *pref) != _ref; pref = &ref->tr_next) {
407 KKASSERT(ref != NULL);
410 KKASSERT(tok->t_cpu == gd);
411 tok->t_cpu = tok->t_reqcpu; /* we do not own 'tok' after this */
412 *pref = ref->tr_next; /* note: also removes giveaway interlock */
415 * If we had gotten the token opportunistically and it still happens to
416 * be queued to a target cpu, we have to wait for the target cpu
417 * to finish processing it. This does not happen very often and does
418 * not need to be optimal.
420 while (ref->tr_magic == LWKT_TOKREF_MAGIC2) {
421 #if defined(MAKE_TOKENS_SPIN)
428 #elif defined(MAKE_TOKENS_YIELD)
431 #error MAKE_TOKENS_XXX ?
437 * Pool tokens are used to provide a type-stable serializing token
438 * pointer that does not race against disappearing data structures.
440 * This routine is called in early boot just after we setup the BSP's
441 * globaldata structure.
444 lwkt_token_pool_init(void)
448 for (i = 0; i < LWKT_NUM_POOL_TOKENS; ++i)
449 lwkt_token_init(&pool_tokens[i]);
453 lwkt_token_pool_get(void *ptraddr)
457 i = ((int)(intptr_t)ptraddr >> 2) ^ ((int)(intptr_t)ptraddr >> 12);
458 return(&pool_tokens[i & LWKT_MASK_POOL_TOKENS]);
464 * This is the receiving side of a remote IPI requesting a token. If we
465 * cannot immediately hand the token off to another cpu we queue it.
467 * NOTE! we 'own' the ref structure, but we only 'own' the token if
471 lwkt_reqtoken_remote(void *data)
473 lwkt_tokref_t ref = data;
474 globaldata_t gd = mycpu;
475 lwkt_token_t tok = ref->tr_tok;
478 * We do not have to queue the token if we can give it away
479 * immediately. Otherwise we queue it to our globaldata structure.
481 KKASSERT(ref->tr_magic == LWKT_TOKREF_MAGIC2);
482 if (lwkt_oktogiveaway_token(tok)) {
483 if (tok->t_cpu == gd)
484 tok->t_cpu = ref->tr_reqgd;
486 ref->tr_magic = LWKT_TOKREF_MAGIC1;
488 ref->tr_gdreqnext = gd->gd_tokreqbase;
489 gd->gd_tokreqbase = ref;
494 * Must be called from a critical section. Satisfy all remote token
495 * requests that are pending on our globaldata structure. The request
496 * does not have to be satisfied with a successful change of ownership
497 * but we do have to acknowledge that we have completed processing the
498 * request by setting the magic number back to MAGIC1.
500 * NOTE! we 'own' the ref structure, but we only 'own' the token if
504 lwkt_drain_token_requests(void)
506 globaldata_t gd = mycpu;
509 while ((ref = gd->gd_tokreqbase) != NULL) {
510 gd->gd_tokreqbase = ref->tr_gdreqnext;
511 KKASSERT(ref->tr_magic == LWKT_TOKREF_MAGIC2);
512 if (ref->tr_tok->t_cpu == gd)
513 ref->tr_tok->t_cpu = ref->tr_reqgd;
515 ref->tr_magic = LWKT_TOKREF_MAGIC1;
522 * Initialize the owner and release-to cpu to the current cpu
523 * and reset the generation count.
526 lwkt_token_init(lwkt_token_t tok)
528 tok->t_cpu = tok->t_reqcpu = mycpu;
532 lwkt_token_uninit(lwkt_token_t tok)