2 * Copyright (c) 2003,2004,2009 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.
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21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * lwkt_token - Implement soft token locks.
38 * Tokens are locks which serialize a thread only while the thread is
39 * running. If the thread blocks all tokens are released, then reacquired
40 * when the thread resumes.
42 * This implementation requires no critical sections or spin locks, but
43 * does use atomic_cmpset_ptr().
45 * Tokens may be recursively acquired by the same thread. However the
46 * caller must be sure to release such tokens in reverse order.
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/kernel.h>
52 #include <sys/rtprio.h>
53 #include <sys/queue.h>
54 #include <sys/sysctl.h>
56 #include <sys/kthread.h>
57 #include <machine/cpu.h>
59 #include <sys/spinlock.h>
61 #include <sys/thread2.h>
62 #include <sys/spinlock2.h>
63 #include <sys/mplock2.h>
66 #include <vm/vm_param.h>
67 #include <vm/vm_kern.h>
68 #include <vm/vm_object.h>
69 #include <vm/vm_page.h>
70 #include <vm/vm_map.h>
71 #include <vm/vm_pager.h>
72 #include <vm/vm_extern.h>
73 #include <vm/vm_zone.h>
75 #include <machine/stdarg.h>
76 #include <machine/smp.h>
83 extern int lwkt_sched_debug;
85 #ifndef LWKT_NUM_POOL_TOKENS
86 #define LWKT_NUM_POOL_TOKENS 4001 /* prime number */
89 struct lwkt_pool_token {
90 struct lwkt_token token;
93 static struct lwkt_pool_token pool_tokens[LWKT_NUM_POOL_TOKENS];
94 struct spinlock tok_debug_spin = SPINLOCK_INITIALIZER(&tok_debug_spin, "tok_debug_spin");
96 #define TOKEN_STRING "REF=%p TOK=%p TD=%p"
97 #define TOKEN_ARGS lwkt_tokref_t ref, lwkt_token_t tok, struct thread *td
98 #define CONTENDED_STRING TOKEN_STRING " (contention started)"
99 #define UNCONTENDED_STRING TOKEN_STRING " (contention stopped)"
100 #if !defined(KTR_TOKENS)
101 #define KTR_TOKENS KTR_ALL
104 KTR_INFO_MASTER(tokens);
105 KTR_INFO(KTR_TOKENS, tokens, fail, 0, TOKEN_STRING, TOKEN_ARGS);
106 KTR_INFO(KTR_TOKENS, tokens, succ, 1, TOKEN_STRING, TOKEN_ARGS);
108 KTR_INFO(KTR_TOKENS, tokens, release, 2, TOKEN_STRING, TOKEN_ARGS);
109 KTR_INFO(KTR_TOKENS, tokens, remote, 3, TOKEN_STRING, TOKEN_ARGS);
110 KTR_INFO(KTR_TOKENS, tokens, reqremote, 4, TOKEN_STRING, TOKEN_ARGS);
111 KTR_INFO(KTR_TOKENS, tokens, reqfail, 5, TOKEN_STRING, TOKEN_ARGS);
112 KTR_INFO(KTR_TOKENS, tokens, drain, 6, TOKEN_STRING, TOKEN_ARGS);
113 KTR_INFO(KTR_TOKENS, tokens, contention_start, 7, CONTENDED_STRING, TOKEN_ARGS);
114 KTR_INFO(KTR_TOKENS, tokens, contention_stop, 7, UNCONTENDED_STRING, TOKEN_ARGS);
117 #define logtoken(name, ref) \
118 KTR_LOG(tokens_ ## name, ref, ref->tr_tok, curthread)
121 * Global tokens. These replace the MP lock for major subsystem locking.
122 * These tokens are initially used to lockup both global and individual
125 * Once individual structures get their own locks these tokens are used
126 * only to protect global lists & other variables and to interlock
127 * allocations and teardowns and such.
129 * The UP initializer causes token acquisition to also acquire the MP lock
130 * for maximum compatibility. The feature may be enabled and disabled at
131 * any time, the MP state is copied to the tokref when the token is acquired
132 * and will not race against sysctl changes.
134 struct lwkt_token mp_token = LWKT_TOKEN_INITIALIZER(mp_token);
135 struct lwkt_token pmap_token = LWKT_TOKEN_INITIALIZER(pmap_token);
136 struct lwkt_token dev_token = LWKT_TOKEN_INITIALIZER(dev_token);
137 struct lwkt_token vm_token = LWKT_TOKEN_INITIALIZER(vm_token);
138 struct lwkt_token vmspace_token = LWKT_TOKEN_INITIALIZER(vmspace_token);
139 struct lwkt_token kvm_token = LWKT_TOKEN_INITIALIZER(kvm_token);
140 struct lwkt_token sigio_token = LWKT_TOKEN_INITIALIZER(sigio_token);
141 struct lwkt_token tty_token = LWKT_TOKEN_INITIALIZER(tty_token);
142 struct lwkt_token vnode_token = LWKT_TOKEN_INITIALIZER(vnode_token);
144 static int lwkt_token_spin = 5;
145 SYSCTL_INT(_lwkt, OID_AUTO, token_spin, CTLFLAG_RW,
146 &lwkt_token_spin, 0, "Decontention spin loops");
147 static int lwkt_token_delay = 0;
148 SYSCTL_INT(_lwkt, OID_AUTO, token_delay, CTLFLAG_RW,
149 &lwkt_token_delay, 0, "Decontention spin delay in ns");
152 * The collision count is bumped every time the LWKT scheduler fails
153 * to acquire needed tokens in addition to a normal lwkt_gettoken()
156 SYSCTL_LONG(_lwkt, OID_AUTO, mp_collisions, CTLFLAG_RW,
157 &mp_token.t_collisions, 0, "Collision counter of mp_token");
158 SYSCTL_LONG(_lwkt, OID_AUTO, pmap_collisions, CTLFLAG_RW,
159 &pmap_token.t_collisions, 0, "Collision counter of pmap_token");
160 SYSCTL_LONG(_lwkt, OID_AUTO, dev_collisions, CTLFLAG_RW,
161 &dev_token.t_collisions, 0, "Collision counter of dev_token");
162 SYSCTL_LONG(_lwkt, OID_AUTO, vm_collisions, CTLFLAG_RW,
163 &vm_token.t_collisions, 0, "Collision counter of vm_token");
164 SYSCTL_LONG(_lwkt, OID_AUTO, vmspace_collisions, CTLFLAG_RW,
165 &vmspace_token.t_collisions, 0, "Collision counter of vmspace_token");
166 SYSCTL_LONG(_lwkt, OID_AUTO, kvm_collisions, CTLFLAG_RW,
167 &kvm_token.t_collisions, 0, "Collision counter of kvm_token");
168 SYSCTL_LONG(_lwkt, OID_AUTO, sigio_collisions, CTLFLAG_RW,
169 &sigio_token.t_collisions, 0, "Collision counter of sigio_token");
170 SYSCTL_LONG(_lwkt, OID_AUTO, tty_collisions, CTLFLAG_RW,
171 &tty_token.t_collisions, 0, "Collision counter of tty_token");
172 SYSCTL_LONG(_lwkt, OID_AUTO, vnode_collisions, CTLFLAG_RW,
173 &vnode_token.t_collisions, 0, "Collision counter of vnode_token");
175 int tokens_debug_output;
176 SYSCTL_INT(_lwkt, OID_AUTO, tokens_debug_output, CTLFLAG_RW,
177 &tokens_debug_output, 0, "Generate stack trace N times");
180 #ifdef DEBUG_LOCKS_LATENCY
182 static long tokens_add_latency;
183 SYSCTL_LONG(_debug, OID_AUTO, tokens_add_latency, CTLFLAG_RW,
184 &tokens_add_latency, 0,
185 "Add spinlock latency");
190 static int _lwkt_getalltokens_sorted(thread_t td);
193 * Acquire the initial mplock
195 * (low level boot only)
198 cpu_get_initial_mplock(void)
200 KKASSERT(mp_token.t_ref == NULL);
201 if (lwkt_trytoken(&mp_token) == FALSE)
202 panic("cpu_get_initial_mplock");
206 * Return a pool token given an address. Use a prime number to reduce
211 _lwkt_token_pool_lookup(void *ptr)
215 i = (u_int)(uintptr_t)ptr % LWKT_NUM_POOL_TOKENS;
216 return (&pool_tokens[i].token);
220 * Initialize a tokref_t prior to making it visible in the thread's
225 _lwkt_tokref_init(lwkt_tokref_t ref, lwkt_token_t tok, thread_t td, long excl)
228 ref->tr_count = excl;
233 * Attempt to acquire a shared or exclusive token. Returns TRUE on success,
236 * If TOK_EXCLUSIVE is set in mode we are attempting to get an exclusive
237 * token, otherwise are attempting to get a shared token.
239 * If TOK_EXCLREQ is set in mode this is a blocking operation, otherwise
240 * it is a non-blocking operation (for both exclusive or shared acquisions).
244 _lwkt_trytokref(lwkt_tokref_t ref, thread_t td, long mode)
251 KASSERT(((mode & TOK_EXCLREQ) == 0 || /* non blocking */
252 td->td_gd->gd_intr_nesting_level == 0 ||
253 panic_cpu_gd == mycpu),
254 ("Attempt to acquire token %p not already "
255 "held in hard code section", tok));
257 if (mode & TOK_EXCLUSIVE) {
259 * Attempt to get an exclusive token
261 count = tok->t_count;
264 oref = tok->t_ref; /* can be NULL */
266 if ((count & ~TOK_EXCLREQ) == 0) {
268 * It is possible to get the exclusive bit.
269 * We must clear TOK_EXCLREQ on successful
272 if (atomic_fcmpset_long(&tok->t_count, &count,
273 (count & ~TOK_EXCLREQ) |
275 KKASSERT(tok->t_ref == NULL);
280 } else if ((count & TOK_EXCLUSIVE) &&
281 oref >= &td->td_toks_base &&
282 oref < td->td_toks_stop) {
284 * Our thread already holds the exclusive
285 * bit, we treat this tokref as a shared
286 * token (sorta) to make the token release
289 * NOTE: oref cannot race above if it
290 * happens to be ours, so we're good.
291 * But we must still have a stable
292 * variable for both parts of the
295 * NOTE: Since we already have an exclusive
296 * lock and don't need to check EXCLREQ
297 * we can just use an atomic_add here
299 atomic_add_long(&tok->t_count, TOK_INCR);
300 ref->tr_count &= ~TOK_EXCLUSIVE;
302 } else if ((mode & TOK_EXCLREQ) &&
303 (count & TOK_EXCLREQ) == 0) {
305 * Unable to get the exclusive bit but being
306 * asked to set the exclusive-request bit.
307 * Since we are going to retry anyway just
308 * set the bit unconditionally.
310 atomic_set_long(&tok->t_count, TOK_EXCLREQ);
314 * Unable to get the exclusive bit and not
315 * being asked to set the exclusive-request
316 * (aka lwkt_trytoken()), or EXCLREQ was
326 * Attempt to get a shared token. Note that TOK_EXCLREQ
327 * for shared tokens simply means the caller intends to
328 * block. We never actually set the bit in tok->t_count.
330 count = tok->t_count;
333 oref = tok->t_ref; /* can be NULL */
335 if ((count & (TOK_EXCLUSIVE/*|TOK_EXCLREQ*/)) == 0) {
337 * It may be possible to get the token shared.
339 if ((atomic_fetchadd_long(&tok->t_count, TOK_INCR) & TOK_EXCLUSIVE) == 0) {
342 count = atomic_fetchadd_long(&tok->t_count,
346 } else if ((count & TOK_EXCLUSIVE) &&
347 oref >= &td->td_toks_base &&
348 oref < td->td_toks_stop) {
350 * We own the exclusive bit on the token so
351 * we can in fact also get it shared.
353 atomic_add_long(&tok->t_count, TOK_INCR);
357 * We failed to get the token shared
368 _lwkt_trytokref_spin(lwkt_tokref_t ref, thread_t td, long mode)
372 if (_lwkt_trytokref(ref, td, mode)) {
373 #ifdef DEBUG_LOCKS_LATENCY
375 for (j = tokens_add_latency; j > 0; --j)
380 for (spin = lwkt_token_spin; spin > 0; --spin) {
381 if (lwkt_token_delay)
382 tsc_delay(lwkt_token_delay);
385 if (_lwkt_trytokref(ref, td, mode)) {
386 #ifdef DEBUG_LOCKS_LATENCY
388 for (j = tokens_add_latency; j > 0; --j)
398 * Release a token that we hold.
402 _lwkt_reltokref(lwkt_tokref_t ref, thread_t td)
408 count = tok->t_count;
412 if (tok->t_ref == ref) {
414 * We are an exclusive holder. We must clear tr_ref
415 * before we clear the TOK_EXCLUSIVE bit. If we are
416 * unable to clear the bit we must restore
419 KKASSERT(count & TOK_EXCLUSIVE);
421 if (atomic_fcmpset_long(&tok->t_count, &count,
422 count & ~TOK_EXCLUSIVE)) {
429 * We are a shared holder
431 KKASSERT(count & TOK_COUNTMASK);
432 if (atomic_fcmpset_long(&tok->t_count, &count,
443 * Obtain all the tokens required by the specified thread on the current
444 * cpu, return 0 on failure and non-zero on success. If a failure occurs
445 * any partially acquired tokens will be released prior to return.
447 * lwkt_getalltokens is called by the LWKT scheduler to re-acquire all
448 * tokens that the thread had to release when it switched away.
450 * If spinning is non-zero this function acquires the tokens in a particular
451 * order to deal with potential deadlocks. We simply use address order for
454 * Called from a critical section.
457 lwkt_getalltokens(thread_t td, int spinning)
463 return(_lwkt_getalltokens_sorted(td));
466 * Acquire tokens in forward order, assign or validate tok->t_ref.
468 for (scan = &td->td_toks_base; scan < td->td_toks_stop; ++scan) {
472 * Only try really hard on the last token
474 if (scan == td->td_toks_stop - 1) {
475 if (_lwkt_trytokref_spin(scan, td, scan->tr_count))
478 if (_lwkt_trytokref(scan, td, scan->tr_count))
483 * Otherwise we failed to acquire all the tokens.
484 * Release whatever we did get.
487 ("token %p is not initialized", tok));
488 td->td_gd->gd_cnt.v_lock_name[0] = 't';
489 strncpy(td->td_gd->gd_cnt.v_lock_name + 1,
491 sizeof(td->td_gd->gd_cnt.v_lock_name) - 2);
492 if (lwkt_sched_debug > 0) {
494 kprintf("toka %p %s %s\n",
495 tok, tok->t_desc, td->td_comm);
497 td->td_wmesg = tok->t_desc;
499 while (--scan >= &td->td_toks_base)
500 _lwkt_reltokref(scan, td);
508 * Release all tokens owned by the specified thread on the current cpu.
510 * This code is really simple. Even in cases where we own all the tokens
511 * note that t_ref may not match the scan for recursively held tokens which
512 * are held deeper in the stack, or for the case where a lwkt_getalltokens()
515 * Tokens are released in reverse order to reduce chasing race failures.
517 * Called from a critical section.
520 lwkt_relalltokens(thread_t td)
525 * Weird order is to try to avoid a panic loop
527 if (td->td_toks_have) {
528 scan = td->td_toks_have;
529 td->td_toks_have = NULL;
531 scan = td->td_toks_stop;
533 while (--scan >= &td->td_toks_base)
534 _lwkt_reltokref(scan, td);
538 * This is the decontention version of lwkt_getalltokens(). The tokens are
539 * acquired in address-sorted order to deal with any deadlocks. Ultimately
540 * token failures will spin into the scheduler and get here.
542 * Called from critical section
546 _lwkt_getalltokens_sorted(thread_t td)
548 lwkt_tokref_t sort_array[LWKT_MAXTOKENS];
556 * Sort the token array. Yah yah, I know this isn't fun.
558 * NOTE: Recursively acquired tokens are ordered the same as in the
559 * td_toks_array so we can always get the earliest one first.
562 scan = &td->td_toks_base;
563 while (scan < td->td_toks_stop) {
564 for (j = 0; j < i; ++j) {
565 if (scan->tr_tok < sort_array[j]->tr_tok)
569 bcopy(sort_array + j, sort_array + j + 1,
570 (i - j) * sizeof(lwkt_tokref_t));
572 sort_array[j] = scan;
579 * Acquire tokens in forward order, assign or validate tok->t_ref.
581 for (i = 0; i < n; ++i) {
582 scan = sort_array[i];
586 * Only try really hard on the last token
588 if (scan == td->td_toks_stop - 1) {
589 if (_lwkt_trytokref_spin(scan, td, scan->tr_count))
592 if (_lwkt_trytokref(scan, td, scan->tr_count))
597 * Otherwise we failed to acquire all the tokens.
598 * Release whatever we did get.
600 td->td_gd->gd_cnt.v_lock_name[0] = 't';
601 strncpy(td->td_gd->gd_cnt.v_lock_name + 1,
603 sizeof(td->td_gd->gd_cnt.v_lock_name) - 2);
604 if (lwkt_sched_debug > 0) {
606 kprintf("tokb %p %s %s\n",
607 tok, tok->t_desc, td->td_comm);
609 td->td_wmesg = tok->t_desc;
612 scan = sort_array[i];
613 _lwkt_reltokref(scan, td);
620 * We were successful, there is no need for another core to signal
627 * Get a serializing token. This routine can block.
630 lwkt_gettoken(lwkt_token_t tok)
632 thread_t td = curthread;
635 ref = td->td_toks_stop;
636 KKASSERT(ref < &td->td_toks_end);
639 _lwkt_tokref_init(ref, tok, td, TOK_EXCLUSIVE|TOK_EXCLREQ);
643 * Taking an exclusive token after holding it shared will
644 * livelock. Scan for that case and assert.
648 for (tk = &td->td_toks_base; tk < ref; tk++) {
649 if (tk->tr_tok != tok)
653 if (tk->tr_count & TOK_EXCLUSIVE)
656 /* We found only shared instances of this token if found >0 here */
657 KASSERT((found == 0), ("Token %p s/x livelock", tok));
661 if (_lwkt_trytokref_spin(ref, td, TOK_EXCLUSIVE|TOK_EXCLREQ))
665 * Give up running if we can't acquire the token right now.
667 * Since the tokref is already active the scheduler now
668 * takes care of acquisition, so we need only call
671 * Since we failed this was not a recursive token so upon
672 * return tr_tok->t_ref should be assigned to this specific
675 td->td_wmesg = tok->t_desc;
678 td->td_toks_have = td->td_toks_stop - 1;
680 if (tokens_debug_output > 0) {
681 --tokens_debug_output;
682 spin_lock(&tok_debug_spin);
683 kprintf("Excl Token thread %p %s %s\n",
684 td, tok->t_desc, td->td_comm);
687 spin_unlock(&tok_debug_spin);
692 KKASSERT(tok->t_ref == ref);
696 * Similar to gettoken but we acquire a shared token instead of an exclusive
700 lwkt_gettoken_shared(lwkt_token_t tok)
702 thread_t td = curthread;
705 ref = td->td_toks_stop;
706 KKASSERT(ref < &td->td_toks_end);
709 _lwkt_tokref_init(ref, tok, td, TOK_EXCLREQ);
713 * Taking a pool token in shared mode is a bad idea; other
714 * addresses deeper in the call stack may hash to the same pool
715 * token and you may end up with an exclusive-shared livelock.
716 * Warn in this condition.
718 if ((tok >= &pool_tokens[0].token) &&
719 (tok < &pool_tokens[LWKT_NUM_POOL_TOKENS].token))
720 kprintf("Warning! Taking pool token %p in shared mode\n", tok);
724 if (_lwkt_trytokref_spin(ref, td, TOK_EXCLREQ))
728 * Give up running if we can't acquire the token right now.
730 * Since the tokref is already active the scheduler now
731 * takes care of acquisition, so we need only call
734 * Since we failed this was not a recursive token so upon
735 * return tr_tok->t_ref should be assigned to this specific
738 td->td_wmesg = tok->t_desc;
741 td->td_toks_have = td->td_toks_stop - 1;
743 if (tokens_debug_output > 0) {
744 --tokens_debug_output;
745 spin_lock(&tok_debug_spin);
746 kprintf("Shar Token thread %p %s %s\n",
747 td, tok->t_desc, td->td_comm);
750 spin_unlock(&tok_debug_spin);
758 * Attempt to acquire a token, return TRUE on success, FALSE on failure.
760 * We setup the tokref in case we actually get the token (if we switch later
761 * it becomes mandatory so we set TOK_EXCLREQ), but we call trytokref without
762 * TOK_EXCLREQ in case we fail.
765 lwkt_trytoken(lwkt_token_t tok)
767 thread_t td = curthread;
770 ref = td->td_toks_stop;
771 KKASSERT(ref < &td->td_toks_end);
774 _lwkt_tokref_init(ref, tok, td, TOK_EXCLUSIVE|TOK_EXCLREQ);
776 if (_lwkt_trytokref(ref, td, TOK_EXCLUSIVE))
780 * Failed, unpend the request
789 lwkt_getpooltoken(void *ptr)
793 tok = _lwkt_token_pool_lookup(ptr);
799 * Release a serializing token.
801 * WARNING! All tokens must be released in reverse order. This will be
805 lwkt_reltoken(lwkt_token_t tok)
807 thread_t td = curthread;
811 * Remove ref from thread token list and assert that it matches
812 * the token passed in. Tokens must be released in reverse order.
814 ref = td->td_toks_stop - 1;
815 KKASSERT(ref >= &td->td_toks_base && ref->tr_tok == tok);
816 _lwkt_reltokref(ref, td);
818 td->td_toks_stop = ref;
822 * It is faster for users of lwkt_getpooltoken() to use the returned
823 * token and just call lwkt_reltoken(), but for convenience we provide
824 * this function which looks the token up based on the ident.
827 lwkt_relpooltoken(void *ptr)
829 lwkt_token_t tok = _lwkt_token_pool_lookup(ptr);
834 * Return a count of the number of token refs the thread has to the
835 * specified token, whether it currently owns the token or not.
838 lwkt_cnttoken(lwkt_token_t tok, thread_t td)
843 for (scan = &td->td_toks_base; scan < td->td_toks_stop; ++scan) {
844 if (scan->tr_tok == tok)
851 * Pool tokens are used to provide a type-stable serializing token
852 * pointer that does not race against disappearing data structures.
854 * This routine is called in early boot just after we setup the BSP's
855 * globaldata structure.
858 lwkt_token_pool_init(void)
862 for (i = 0; i < LWKT_NUM_POOL_TOKENS; ++i)
863 lwkt_token_init(&pool_tokens[i].token, "pool");
867 lwkt_token_pool_lookup(void *ptr)
869 return (_lwkt_token_pool_lookup(ptr));
873 * Initialize a token.
876 lwkt_token_init(lwkt_token_t tok, const char *desc)
880 tok->t_collisions = 0;
885 lwkt_token_uninit(lwkt_token_t tok)
891 * Exchange the two most recent tokens on the tokref stack. This allows
892 * you to release a token out of order.
894 * We have to be careful about the case where the top two tokens are
895 * the same token. In this case tok->t_ref will point to the deeper
896 * ref and must remain pointing to the deeper ref. If we were to swap
897 * it the first release would clear the token even though a second
898 * ref is still present.
900 * Only exclusively held tokens contain a reference to the tokref which
901 * has to be flipped along with the swap.
904 lwkt_token_swap(void)
906 lwkt_tokref_t ref1, ref2;
907 lwkt_token_t tok1, tok2;
909 thread_t td = curthread;
913 ref1 = td->td_toks_stop - 1;
914 ref2 = td->td_toks_stop - 2;
915 KKASSERT(ref1 >= &td->td_toks_base);
916 KKASSERT(ref2 >= &td->td_toks_base);
920 count1 = ref1->tr_count;
921 count2 = ref2->tr_count;
925 ref1->tr_count = count2;
927 ref2->tr_count = count1;
928 if (tok1->t_ref == ref1)
930 if (tok2->t_ref == ref2)
938 DB_SHOW_COMMAND(tokens, db_tok_all)
940 struct lwkt_token *tok, **ptr;
941 struct lwkt_token *toklist[16] = {
955 for (tok = *ptr; tok; tok = *(++ptr)) {
956 db_printf("tok=%p tr_owner=%p t_colissions=%ld t_desc=%s\n", tok,
957 (tok->t_ref ? tok->t_ref->tr_owner : NULL),
958 tok->t_collisions, tok->t_desc);