kernel - Provide descriptions for lwkt.* and debug.* sysctl's
[dragonfly.git] / sys / kern / lwkt_token.c
CommitLineData
c31b1324 1/*
c6fbe95a 2 * Copyright (c) 2003,2004,2009 The DragonFly Project. All rights reserved.
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3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
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7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
8c10bfcf 10 *
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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
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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.
20 *
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
c31b1324 32 * SUCH DAMAGE.
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33 */
34
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35/*
36 * lwkt_token - Implement soft token locks.
37 *
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.
41 *
42 * This implementation requires no critical sections or spin locks, but
43 * does use atomic_cmpset_ptr().
44 *
45 * Tokens may be recursively acquired by the same thread. However the
46 * caller must be sure to release such tokens in reverse order.
47 */
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48#include <sys/param.h>
49#include <sys/systm.h>
50#include <sys/kernel.h>
51#include <sys/proc.h>
52#include <sys/rtprio.h>
53#include <sys/queue.h>
c31b1324 54#include <sys/sysctl.h>
4883dbe9 55#include <sys/ktr.h>
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56#include <sys/kthread.h>
57#include <machine/cpu.h>
58#include <sys/lock.h>
59#include <sys/caps.h>
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60#include <sys/spinlock.h>
61
62#include <sys/thread2.h>
63#include <sys/spinlock2.h>
3b998fa9 64#include <sys/mplock2.h>
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65
66#include <vm/vm.h>
67#include <vm/vm_param.h>
68#include <vm/vm_kern.h>
69#include <vm/vm_object.h>
70#include <vm/vm_page.h>
71#include <vm/vm_map.h>
72#include <vm/vm_pager.h>
73#include <vm/vm_extern.h>
74#include <vm/vm_zone.h>
75
76#include <machine/stdarg.h>
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77#include <machine/smp.h>
78
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79#ifndef LWKT_NUM_POOL_TOKENS
80#define LWKT_NUM_POOL_TOKENS 1024 /* power of 2 */
81#endif
82#define LWKT_MASK_POOL_TOKENS (LWKT_NUM_POOL_TOKENS - 1)
83
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84static lwkt_token pool_tokens[LWKT_NUM_POOL_TOKENS];
85
f917e9bc 86#define TOKEN_STRING "REF=%p TOK=%p TD=%p"
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87#define CONTENDED_STRING "REF=%p TOK=%p TD=%p (contention started)"
88#define UNCONTENDED_STRING "REF=%p TOK=%p TD=%p (contention stopped)"
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89#if !defined(KTR_TOKENS)
90#define KTR_TOKENS KTR_ALL
91#endif
790e4db7 92
4883dbe9 93KTR_INFO_MASTER(tokens);
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94KTR_INFO(KTR_TOKENS, tokens, fail, 0, TOKEN_STRING, sizeof(void *) * 3);
95KTR_INFO(KTR_TOKENS, tokens, succ, 1, TOKEN_STRING, sizeof(void *) * 3);
7cd8d145 96#if 0
c6fbe95a 97KTR_INFO(KTR_TOKENS, tokens, release, 2, TOKEN_STRING, sizeof(void *) * 3);
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98KTR_INFO(KTR_TOKENS, tokens, remote, 3, TOKEN_STRING, sizeof(void *) * 3);
99KTR_INFO(KTR_TOKENS, tokens, reqremote, 4, TOKEN_STRING, sizeof(void *) * 3);
100KTR_INFO(KTR_TOKENS, tokens, reqfail, 5, TOKEN_STRING, sizeof(void *) * 3);
101KTR_INFO(KTR_TOKENS, tokens, drain, 6, TOKEN_STRING, sizeof(void *) * 3);
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102KTR_INFO(KTR_TOKENS, tokens, contention_start, 7, CONTENDED_STRING, sizeof(void *) * 3);
103KTR_INFO(KTR_TOKENS, tokens, contention_stop, 7, UNCONTENDED_STRING, sizeof(void *) * 3);
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104#endif
105
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106#define logtoken(name, ref) \
107 KTR_LOG(tokens_ ## name, ref, ref->tr_tok, curthread)
4883dbe9 108
c31b1324 109/*
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110 * Global tokens. These replace the MP lock for major subsystem locking.
111 * These tokens are initially used to lockup both global and individual
112 * operations.
113 *
114 * Once individual structures get their own locks these tokens are used
115 * only to protect global lists & other variables and to interlock
116 * allocations and teardowns and such.
117 *
118 * The UP initializer causes token acquisition to also acquire the MP lock
119 * for maximum compatibility. The feature may be enabled and disabled at
120 * any time, the MP state is copied to the tokref when the token is acquired
121 * and will not race against sysctl changes.
122 */
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123struct lwkt_token pmap_token = LWKT_TOKEN_UP_INITIALIZER(pmap_token);
124struct lwkt_token dev_token = LWKT_TOKEN_UP_INITIALIZER(dev_token);
125struct lwkt_token vm_token = LWKT_TOKEN_UP_INITIALIZER(vm_token);
126struct lwkt_token vmspace_token = LWKT_TOKEN_UP_INITIALIZER(vmspace_token);
127struct lwkt_token kvm_token = LWKT_TOKEN_UP_INITIALIZER(kvm_token);
128struct lwkt_token proc_token = LWKT_TOKEN_UP_INITIALIZER(proc_token);
129struct lwkt_token tty_token = LWKT_TOKEN_UP_INITIALIZER(tty_token);
130struct lwkt_token vnode_token = LWKT_TOKEN_UP_INITIALIZER(vnode_token);
2de4f77e 131struct lwkt_token vmobj_token = LWKT_TOKEN_UP_INITIALIZER(vmobj_token);
c9aa7a82 132
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133SYSCTL_INT(_lwkt, OID_AUTO, pmap_mpsafe, CTLFLAG_RW,
134 &pmap_token.t_flags, 0, "Require MP lock for pmap_token");
135SYSCTL_INT(_lwkt, OID_AUTO, dev_mpsafe, CTLFLAG_RW,
136 &dev_token.t_flags, 0, "Require MP lock for dev_token");
137SYSCTL_INT(_lwkt, OID_AUTO, vm_mpsafe, CTLFLAG_RW,
138 &vm_token.t_flags, 0, "Require MP lock for vm_token");
139SYSCTL_INT(_lwkt, OID_AUTO, vmspace_mpsafe, CTLFLAG_RW,
140 &vmspace_token.t_flags, 0, "Require MP lock for vmspace_token");
141SYSCTL_INT(_lwkt, OID_AUTO, kvm_mpsafe, CTLFLAG_RW,
142 &kvm_token.t_flags, 0, "Require MP lock for kvm_token");
143SYSCTL_INT(_lwkt, OID_AUTO, proc_mpsafe, CTLFLAG_RW,
144 &proc_token.t_flags, 0, "Require MP lock for proc_token");
145SYSCTL_INT(_lwkt, OID_AUTO, tty_mpsafe, CTLFLAG_RW,
146 &tty_token.t_flags, 0, "Require MP lock for tty_token");
147SYSCTL_INT(_lwkt, OID_AUTO, vnode_mpsafe, CTLFLAG_RW,
148 &vnode_token.t_flags, 0, "Require MP lock for vnode_token");
149SYSCTL_INT(_lwkt, OID_AUTO, vmobj_mpsafe, CTLFLAG_RW,
150 &vmobj_token.t_flags, 0, "Require MP lock for vmobj_token");
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151
152/*
153 * The collision count is bumped every time the LWKT scheduler fails
154 * to acquire needed tokens in addition to a normal lwkt_gettoken()
155 * stall.
156 */
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157SYSCTL_LONG(_lwkt, OID_AUTO, pmap_collisions, CTLFLAG_RW,
158 &pmap_token.t_collisions, 0, "Collision counter of pmap_token");
159SYSCTL_LONG(_lwkt, OID_AUTO, dev_collisions, CTLFLAG_RW,
160 &dev_token.t_collisions, 0, "Collision counter of dev_token");
161SYSCTL_LONG(_lwkt, OID_AUTO, vm_collisions, CTLFLAG_RW,
162 &vm_token.t_collisions, 0, "Collision counter of vm_token");
163SYSCTL_LONG(_lwkt, OID_AUTO, vmspace_collisions, CTLFLAG_RW,
164 &vmspace_token.t_collisions, 0, "Collision counter of vmspace_token");
165SYSCTL_LONG(_lwkt, OID_AUTO, kvm_collisions, CTLFLAG_RW,
166 &kvm_token.t_collisions, 0, "Collision counter of kvm_token");
167SYSCTL_LONG(_lwkt, OID_AUTO, proc_collisions, CTLFLAG_RW,
168 &proc_token.t_collisions, 0, "Collision counter of proc_token");
169SYSCTL_LONG(_lwkt, OID_AUTO, tty_collisions, CTLFLAG_RW,
170 &tty_token.t_collisions, 0, "Collision counter of tty_token");
171SYSCTL_LONG(_lwkt, OID_AUTO, vnode_collisions, CTLFLAG_RW,
172 &vnode_token.t_collisions, 0, "Collision counter of vnode_token");
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173
174/*
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175 * Return a pool token given an address
176 */
177static __inline
178lwkt_token_t
179_lwkt_token_pool_lookup(void *ptr)
180{
181 int i;
182
183 i = ((int)(intptr_t)ptr >> 2) ^ ((int)(intptr_t)ptr >> 12);
184 return(&pool_tokens[i & LWKT_MASK_POOL_TOKENS]);
185}
186
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187/*
188 * Initialize a tokref_t prior to making it visible in the thread's
189 * token array.
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190 *
191 * As an optimization we set the MPSAFE flag if the thread is already
192 * holding the MP lock. This bypasses unncessary calls to get_mplock() and
193 * rel_mplock() on tokens which are not normally MPSAFE when the thread
194 * is already holding the MP lock.
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195 *
196 * WARNING: The inherited td_xpcount does not count here because a switch
197 * could schedule the preempted thread and blow away the inherited
198 * mplock.
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199 */
200static __inline
201void
202_lwkt_tokref_init(lwkt_tokref_t ref, lwkt_token_t tok, thread_t td)
203{
204 ref->tr_tok = tok;
205 ref->tr_owner = td;
206 ref->tr_flags = tok->t_flags;
d7ec0cb4 207#ifdef SMP
c843cbf7 208 if (td->td_mpcount)
d7ec0cb4 209#endif
c843cbf7 210 ref->tr_flags |= LWKT_TOKEN_MPSAFE;
3b998fa9 211}
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212
213/*
9d265729 214 * Obtain all the tokens required by the specified thread on the current
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215 * cpu, return 0 on failure and non-zero on success. If a failure occurs
216 * any partially acquired tokens will be released prior to return.
dd55d707 217 *
7eb611ef 218 * lwkt_getalltokens is called by the LWKT scheduler to acquire all
24c80b2b 219 * tokens that the thread had acquired prior to going to sleep.
7eb611ef 220 *
3b998fa9 221 * The scheduler is responsible for maintaining the MP lock count, so
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222 * we don't need to deal with tr_flags here. We also do not do any
223 * logging here. The logging done by lwkt_gettoken() is plenty good
224 * enough to get a feel for it.
3b998fa9 225 *
7eb611ef 226 * Called from a critical section.
c31b1324 227 */
41a01a4d 228int
b37f18d6 229lwkt_getalltokens(thread_t td, const char **msgp, const void **addrp)
41a01a4d 230{
3b998fa9 231 lwkt_tokref_t scan;
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232 lwkt_tokref_t ref;
233 lwkt_token_t tok;
234
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235 /*
236 * Acquire tokens in forward order, assign or validate tok->t_ref.
237 */
238 for (scan = &td->td_toks_base; scan < td->td_toks_stop; ++scan) {
239 tok = scan->tr_tok;
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240 for (;;) {
241 /*
242 * Try to acquire the token if we do not already have
243 * it.
244 *
245 * NOTE: If atomic_cmpset_ptr() fails we have to
246 * loop and try again. It just means we
247 * lost a cpu race.
248 */
249 ref = tok->t_ref;
c6fbe95a 250 if (ref == NULL) {
3b998fa9 251 if (atomic_cmpset_ptr(&tok->t_ref, NULL, scan))
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252 break;
253 continue;
254 }
255
256 /*
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257 * Test if ref is already recursively held by this
258 * thread. We cannot safely dereference tok->t_ref
259 * (it might belong to another thread and is thus
260 * unstable), but we don't have to. We can simply
261 * range-check it.
c6fbe95a 262 */
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263 if (ref >= &td->td_toks_base && ref < td->td_toks_stop)
264 break;
265
266 /*
267 * Otherwise we failed to acquire all the tokens.
268 * Undo and return.
269 */
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270 *msgp = tok->t_desc;
271 *addrp = scan->tr_stallpc;
c9aa7a82 272 atomic_add_long(&tok->t_collisions, 1);
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273 lwkt_relalltokens(td);
274 return(FALSE);
38717797 275 }
41a01a4d 276 }
c6fbe95a 277 return (TRUE);
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278}
279
41a01a4d 280/*
9d265729 281 * Release all tokens owned by the specified thread on the current cpu.
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282 *
283 * This code is really simple. Even in cases where we own all the tokens
284 * note that t_ref may not match the scan for recursively held tokens,
285 * or for the case where a lwkt_getalltokens() failed.
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286 *
287 * The scheduler is responsible for maintaining the MP lock count, so
288 * we don't need to deal with tr_flags here.
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289 *
290 * Called from a critical section.
41a01a4d 291 */
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292void
293lwkt_relalltokens(thread_t td)
41a01a4d 294{
3b998fa9 295 lwkt_tokref_t scan;
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296 lwkt_token_t tok;
297
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298 for (scan = &td->td_toks_base; scan < td->td_toks_stop; ++scan) {
299 tok = scan->tr_tok;
300 if (tok->t_ref == scan)
c6fbe95a 301 tok->t_ref = NULL;
41a01a4d 302 }
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303}
304
41a01a4d 305/*
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306 * Token acquisition helper function. The caller must have already
307 * made nref visible by adjusting td_toks_stop and will be responsible
308 * for the disposition of nref on either success or failure.
dd55d707 309 *
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310 * When acquiring tokens recursively we want tok->t_ref to point to
311 * the outer (first) acquisition so it gets cleared only on the last
312 * release.
41a01a4d 313 */
41a01a4d 314static __inline
7eb611ef 315int
4a28fe22 316_lwkt_trytokref2(lwkt_tokref_t nref, thread_t td, int blocking)
41a01a4d 317{
c6fbe95a 318 lwkt_token_t tok;
3b998fa9 319 lwkt_tokref_t ref;
c6fbe95a 320
7eb611ef 321 /*
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322 * Make sure the compiler does not reorder prior instructions
323 * beyond this demark.
7eb611ef 324 */
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325 cpu_ccfence();
326
7eb611ef 327 /*
c6fbe95a 328 * Attempt to gain ownership
7eb611ef 329 */
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330 tok = nref->tr_tok;
331 for (;;) {
332 /*
333 * Try to acquire the token if we do not already have
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334 * it. This is not allowed if we are in a hard code
335 * section (because it 'might' have blocked).
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336 */
337 ref = tok->t_ref;
c6fbe95a 338 if (ref == NULL) {
4a28fe22 339 KASSERT((blocking == 0 ||
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340 td->td_gd->gd_intr_nesting_level == 0 ||
341 panic_cpu_gd == mycpu),
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342 ("Attempt to acquire token %p not already "
343 "held in hard code section", tok));
5fddbda2 344
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345 /*
346 * NOTE: If atomic_cmpset_ptr() fails we have to
347 * loop and try again. It just means we
348 * lost a cpu race.
349 */
350 if (atomic_cmpset_ptr(&tok->t_ref, NULL, nref))
351 return (TRUE);
352 continue;
353 }
354
355 /*
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356 * Test if ref is already recursively held by this
357 * thread. We cannot safely dereference tok->t_ref
358 * (it might belong to another thread and is thus
359 * unstable), but we don't have to. We can simply
360 * range-check it.
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361 *
362 * It is ok to acquire a token that is already held
363 * by the current thread when in a hard code section.
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364 */
365 if (ref >= &td->td_toks_base && ref < td->td_toks_stop)
366 return(TRUE);
367
368 /*
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369 * Otherwise we failed, and it is not ok to attempt to
370 * acquire a token in a hard code section.
c6fbe95a 371 */
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372 KASSERT((blocking == 0 ||
373 td->td_gd->gd_intr_nesting_level == 0),
374 ("Attempt to acquire token %p not already "
375 "held in hard code section", tok));
376
c6fbe95a 377 return(FALSE);
dd55d707 378 }
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379}
380
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381/*
382 * Acquire a serializing token. This routine does not block.
383 */
41a01a4d 384static __inline
c31b1324 385int
c6fbe95a 386_lwkt_trytokref(lwkt_tokref_t ref, thread_t td)
c31b1324 387{
3b998fa9 388 if ((ref->tr_flags & LWKT_TOKEN_MPSAFE) == 0) {
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389 if (try_mplock() == 0) {
390 --td->td_toks_stop;
3b998fa9 391 return (FALSE);
3933a3ab 392 }
3b998fa9 393 }
4a28fe22 394 if (_lwkt_trytokref2(ref, td, 0) == FALSE) {
c6fbe95a 395 /*
3b998fa9 396 * Cleanup, deactivate the failed token.
c6fbe95a 397 */
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398 if ((ref->tr_flags & LWKT_TOKEN_MPSAFE) == 0)
399 rel_mplock();
3933a3ab 400 --td->td_toks_stop;
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401 return (FALSE);
402 }
403 return (TRUE);
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404}
405
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406/*
407 * Acquire a serializing token. This routine can block.
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408 */
409static __inline
410void
b37f18d6 411_lwkt_gettokref(lwkt_tokref_t ref, thread_t td, const void **stkframe)
7eb611ef 412{
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413 if ((ref->tr_flags & LWKT_TOKEN_MPSAFE) == 0)
414 get_mplock();
4a28fe22 415 if (_lwkt_trytokref2(ref, td, 1) == FALSE) {
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416 /*
417 * Give up running if we can't acquire the token right now.
c6fbe95a 418 *
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419 * Since the tokref is already active the scheduler now
420 * takes care of acquisition, so we need only call
f9235b6d 421 * lwkt_switch().
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422 *
423 * Since we failed this was not a recursive token so upon
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424 * return tr_tok->t_ref should be assigned to this specific
425 * ref.
426 */
b37f18d6 427 ref->tr_stallpc = stkframe[-1];
c9aa7a82 428 atomic_add_long(&ref->tr_tok->t_collisions, 1);
c6fbe95a 429 logtoken(fail, ref);
f9235b6d 430 lwkt_switch();
c6fbe95a 431 logtoken(succ, ref);
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432 KKASSERT(ref->tr_tok->t_ref == ref);
433 }
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434}
435
41a01a4d 436void
3b998fa9 437lwkt_gettoken(lwkt_token_t tok)
c31b1324 438{
c6fbe95a 439 thread_t td = curthread;
3b998fa9 440 lwkt_tokref_t ref;
c6fbe95a 441
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442 ref = td->td_toks_stop;
443 KKASSERT(ref < &td->td_toks_end);
3b998fa9 444 ++td->td_toks_stop;
b528f10f 445 cpu_ccfence();
3933a3ab 446 _lwkt_tokref_init(ref, tok, td);
b37f18d6 447 _lwkt_gettokref(ref, td, (const void **)&tok);
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448}
449
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450void
451lwkt_gettoken_hard(lwkt_token_t tok)
452{
453 thread_t td = curthread;
454 lwkt_tokref_t ref;
455
456 ref = td->td_toks_stop;
457 KKASSERT(ref < &td->td_toks_end);
4a28fe22 458 ++td->td_toks_stop;
b528f10f 459 cpu_ccfence();
3933a3ab 460 _lwkt_tokref_init(ref, tok, td);
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461 _lwkt_gettokref(ref, td, (const void **)&tok);
462 crit_enter_hard_gd(td->td_gd);
463}
464
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465lwkt_token_t
466lwkt_getpooltoken(void *ptr)
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467{
468 thread_t td = curthread;
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469 lwkt_token_t tok;
470 lwkt_tokref_t ref;
c6fbe95a 471
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472 ref = td->td_toks_stop;
473 KKASSERT(ref < &td->td_toks_end);
3933a3ab 474 ++td->td_toks_stop;
b528f10f 475 cpu_ccfence();
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476 tok = _lwkt_token_pool_lookup(ptr);
477 _lwkt_tokref_init(ref, tok, td);
b37f18d6 478 _lwkt_gettokref(ref, td, (const void **)&ptr);
3b998fa9 479 return(tok);
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480}
481
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482/*
483 * Attempt to acquire a token, return TRUE on success, FALSE on failure.
484 */
c31b1324 485int
3b998fa9 486lwkt_trytoken(lwkt_token_t tok)
c31b1324 487{
c6fbe95a 488 thread_t td = curthread;
3b998fa9 489 lwkt_tokref_t ref;
c6fbe95a 490
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491 ref = td->td_toks_stop;
492 KKASSERT(ref < &td->td_toks_end);
3b998fa9 493 ++td->td_toks_stop;
b528f10f 494 cpu_ccfence();
3933a3ab 495 _lwkt_tokref_init(ref, tok, td);
c6fbe95a 496 return(_lwkt_trytokref(ref, td));
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497}
498
c31b1324 499/*
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500 * Release a serializing token.
501 *
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502 * WARNING! All tokens must be released in reverse order. This will be
503 * asserted.
c31b1324 504 */
41a01a4d 505void
3b998fa9 506lwkt_reltoken(lwkt_token_t tok)
c31b1324 507{
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508 thread_t td = curthread;
509 lwkt_tokref_t ref;
c6fbe95a 510
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511 /*
512 * Remove ref from thread token list and assert that it matches
513 * the token passed in. Tokens must be released in reverse order.
514 */
515 ref = td->td_toks_stop - 1;
516 KKASSERT(ref >= &td->td_toks_base && ref->tr_tok == tok);
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517
518 /*
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519 * Only clear the token if it matches ref. If ref was a recursively
520 * acquired token it may not match.
521 *
3b998fa9 522 * If the token was not MPSAFE release the MP lock.
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523 *
524 * NOTE: We have to do this before adjust td_toks_stop, otherwise
525 * a fast interrupt can come along and reuse our ref while
526 * tok is still attached to it.
3b998fa9 527 */
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528 if (tok->t_ref == ref)
529 tok->t_ref = NULL;
530 cpu_ccfence();
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531 if ((ref->tr_flags & LWKT_TOKEN_MPSAFE) == 0)
532 rel_mplock();
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533
534 /*
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535 * Finally adjust td_toks_stop, be very sure that the compiler
536 * does not reorder the clearing of tok->t_ref with the
537 * decrementing of td->td_toks_stop.
c6fbe95a 538 */
c6fbe95a 539 cpu_ccfence();
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540 td->td_toks_stop = ref;
541 KKASSERT(tok->t_ref != ref);
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542}
543
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544void
545lwkt_reltoken_hard(lwkt_token_t tok)
546{
547 lwkt_reltoken(tok);
548 crit_exit_hard();
549}
550
41a01a4d 551/*
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552 * It is faster for users of lwkt_getpooltoken() to use the returned
553 * token and just call lwkt_reltoken(), but for convenience we provide
554 * this function which looks the token up based on the ident.
555 */
556void
557lwkt_relpooltoken(void *ptr)
558{
559 lwkt_token_t tok = _lwkt_token_pool_lookup(ptr);
560 lwkt_reltoken(tok);
561}
562
563
564/*
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565 * Pool tokens are used to provide a type-stable serializing token
566 * pointer that does not race against disappearing data structures.
567 *
568 * This routine is called in early boot just after we setup the BSP's
569 * globaldata structure.
570 */
571void
572lwkt_token_pool_init(void)
573{
c6fbe95a 574 int i;
41a01a4d 575
c6fbe95a 576 for (i = 0; i < LWKT_NUM_POOL_TOKENS; ++i)
b37f18d6 577 lwkt_token_init(&pool_tokens[i], 1, "pool");
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578}
579
580lwkt_token_t
c6fbe95a 581lwkt_token_pool_lookup(void *ptr)
41a01a4d 582{
c6fbe95a 583 return (_lwkt_token_pool_lookup(ptr));
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584}
585
41a01a4d 586/*
544c38e8
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587 * Initialize a token. If mpsafe is 0, the MP lock is acquired before
588 * acquiring the token and released after releasing the token.
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589 */
590void
b37f18d6 591lwkt_token_init(lwkt_token_t tok, int mpsafe, const char *desc)
41a01a4d 592{
c6fbe95a 593 tok->t_ref = NULL;
3b998fa9 594 tok->t_flags = mpsafe ? LWKT_TOKEN_MPSAFE : 0;
73d8e728 595 tok->t_collisions = 0;
c5724852 596 tok->t_desc = desc;
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597}
598
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599void
600lwkt_token_uninit(lwkt_token_t tok)
601{
c6fbe95a 602 /* empty */
41a01a4d 603}
7eb611ef 604
c6fbe95a 605#if 0
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606int
607lwkt_token_is_stale(lwkt_tokref_t ref)
608{
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609 lwkt_token_t tok = ref->tr_tok;
610
611 KKASSERT(tok->t_owner == curthread && ref->tr_state == 1 &&
612 tok->t_count > 0);
613
614 /* Token is not stale */
615 if (tok->t_lastowner == tok->t_owner)
616 return (FALSE);
617
618 /*
619 * The token is stale. Reset to not stale so that the next call to
620 * lwkt_token_is_stale will return "not stale" unless the token
621 * was acquired in-between by another thread.
622 */
623 tok->t_lastowner = tok->t_owner;
624 return (TRUE);
7eb611ef 625}
c6fbe95a 626#endif