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fa8d436c | 1 | /* Malloc implementation for multiple threads without lock contention. |
bfff8b1b | 2 | Copyright (C) 2001-2017 Free Software Foundation, Inc. |
fa8d436c UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Wolfram Gloger <wg@malloc.de>, 2001. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
cc7375ce RM |
7 | modify it under the terms of the GNU Lesser General Public License as |
8 | published by the Free Software Foundation; either version 2.1 of the | |
fa8d436c UD |
9 | License, or (at your option) any later version. |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
cc7375ce | 14 | Lesser General Public License for more details. |
fa8d436c | 15 | |
cc7375ce | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
17 | License along with the GNU C Library; see the file COPYING.LIB. If |
18 | not, see <http://www.gnu.org/licenses/>. */ | |
fa8d436c | 19 | |
a28b6b0a RM |
20 | #include <stdbool.h> |
21 | ||
67e58f39 SP |
22 | #if HAVE_TUNABLES |
23 | # define TUNABLE_NAMESPACE malloc | |
24 | #endif | |
25 | #include <elf/dl-tunables.h> | |
26 | ||
fa8d436c UD |
27 | /* Compile-time constants. */ |
28 | ||
6c8dbf00 | 29 | #define HEAP_MIN_SIZE (32 * 1024) |
fa8d436c | 30 | #ifndef HEAP_MAX_SIZE |
e404fb16 | 31 | # ifdef DEFAULT_MMAP_THRESHOLD_MAX |
bd2c2341 | 32 | # define HEAP_MAX_SIZE (2 * DEFAULT_MMAP_THRESHOLD_MAX) |
e404fb16 | 33 | # else |
6c8dbf00 | 34 | # define HEAP_MAX_SIZE (1024 * 1024) /* must be a power of two */ |
e404fb16 | 35 | # endif |
fa8d436c UD |
36 | #endif |
37 | ||
38 | /* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps | |
39 | that are dynamically created for multi-threaded programs. The | |
40 | maximum size must be a power of two, for fast determination of | |
41 | which heap belongs to a chunk. It should be much larger than the | |
42 | mmap threshold, so that requests with a size just below that | |
43 | threshold can be fulfilled without creating too many heaps. */ | |
44 | ||
fa8d436c UD |
45 | /***************************************************************************/ |
46 | ||
47 | #define top(ar_ptr) ((ar_ptr)->top) | |
48 | ||
49 | /* A heap is a single contiguous memory region holding (coalesceable) | |
50 | malloc_chunks. It is allocated with mmap() and always starts at an | |
22a89187 | 51 | address aligned to HEAP_MAX_SIZE. */ |
fa8d436c | 52 | |
6c8dbf00 OB |
53 | typedef struct _heap_info |
54 | { | |
fa8d436c UD |
55 | mstate ar_ptr; /* Arena for this heap. */ |
56 | struct _heap_info *prev; /* Previous heap. */ | |
57 | size_t size; /* Current size in bytes. */ | |
6c8dbf00 OB |
58 | size_t mprotect_size; /* Size in bytes that has been mprotected |
59 | PROT_READ|PROT_WRITE. */ | |
7d013a64 RM |
60 | /* Make sure the following data is properly aligned, particularly |
61 | that sizeof (heap_info) + 2 * SIZE_SZ is a multiple of | |
c7fd3362 JJ |
62 | MALLOC_ALIGNMENT. */ |
63 | char pad[-6 * SIZE_SZ & MALLOC_ALIGN_MASK]; | |
fa8d436c UD |
64 | } heap_info; |
65 | ||
7d013a64 RM |
66 | /* Get a compile-time error if the heap_info padding is not correct |
67 | to make alignment work as expected in sYSMALLOc. */ | |
68 | extern int sanity_check_heap_info_alignment[(sizeof (heap_info) | |
6c8dbf00 OB |
69 | + 2 * SIZE_SZ) % MALLOC_ALIGNMENT |
70 | ? -1 : 1]; | |
7d013a64 | 71 | |
6782806d FW |
72 | /* Thread specific data. */ |
73 | ||
74 | static __thread mstate thread_arena attribute_tls_model_ie; | |
75 | ||
90c400bd FW |
76 | /* Arena free list. free_list_lock synchronizes access to the |
77 | free_list variable below, and the next_free and attached_threads | |
78 | members of struct malloc_state objects. No other locks must be | |
79 | acquired after free_list_lock has been acquired. */ | |
fa8d436c | 80 | |
cbb47fa1 | 81 | __libc_lock_define_initialized (static, free_list_lock); |
02d46fc4 | 82 | static size_t narenas = 1; |
425ce2ed | 83 | static mstate free_list; |
fa8d436c | 84 | |
90c400bd FW |
85 | /* list_lock prevents concurrent writes to the next member of struct |
86 | malloc_state objects. | |
87 | ||
88 | Read access to the next member is supposed to synchronize with the | |
89 | atomic_write_barrier and the write to the next member in | |
90 | _int_new_arena. This suffers from data races; see the FIXME | |
91 | comments in _int_new_arena and reused_arena. | |
92 | ||
7962541a FW |
93 | list_lock also prevents concurrent forks. At the time list_lock is |
94 | acquired, no arena lock must have been acquired, but it is | |
95 | permitted to acquire arena locks subsequently, while list_lock is | |
96 | acquired. */ | |
cbb47fa1 | 97 | __libc_lock_define_initialized (static, list_lock); |
90c400bd | 98 | |
2a652f5a RM |
99 | /* Already initialized? */ |
100 | int __malloc_initialized = -1; | |
101 | ||
fa8d436c UD |
102 | /**************************************************************************/ |
103 | ||
fa8d436c UD |
104 | |
105 | /* arena_get() acquires an arena and locks the corresponding mutex. | |
106 | First, try the one last locked successfully by this thread. (This | |
107 | is the common case and handled with a macro for speed.) Then, loop | |
108 | once over the circularly linked list of arenas. If no arena is | |
109 | readily available, create a new one. In this latter case, `size' | |
110 | is just a hint as to how much memory will be required immediately | |
111 | in the new arena. */ | |
112 | ||
113 | #define arena_get(ptr, size) do { \ | |
6782806d | 114 | ptr = thread_arena; \ |
6c8dbf00 OB |
115 | arena_lock (ptr, size); \ |
116 | } while (0) | |
425ce2ed | 117 | |
6c8dbf00 | 118 | #define arena_lock(ptr, size) do { \ |
a9da0bb2 | 119 | if (ptr) \ |
cbb47fa1 | 120 | __libc_lock_lock (ptr->mutex); \ |
6c8dbf00 | 121 | else \ |
92a9b22d | 122 | ptr = arena_get2 ((size), NULL); \ |
6c8dbf00 | 123 | } while (0) |
fa8d436c UD |
124 | |
125 | /* find the heap and corresponding arena for a given ptr */ | |
126 | ||
127 | #define heap_for_ptr(ptr) \ | |
6c8dbf00 | 128 | ((heap_info *) ((unsigned long) (ptr) & ~(HEAP_MAX_SIZE - 1))) |
fa8d436c | 129 | #define arena_for_chunk(ptr) \ |
e9c4fe93 | 130 | (chunk_main_arena (ptr) ? &main_arena : heap_for_ptr (ptr)->ar_ptr) |
fa8d436c | 131 | |
fa8d436c UD |
132 | |
133 | /**************************************************************************/ | |
134 | ||
fa8d436c UD |
135 | /* atfork support. */ |
136 | ||
29d79486 FW |
137 | /* The following three functions are called around fork from a |
138 | multi-threaded process. We do not use the general fork handler | |
139 | mechanism to make sure that our handlers are the last ones being | |
140 | called, so that other fork handlers can use the malloc | |
141 | subsystem. */ | |
fa8d436c | 142 | |
29d79486 FW |
143 | void |
144 | __malloc_fork_lock_parent (void) | |
fa8d436c | 145 | { |
6c8dbf00 | 146 | if (__malloc_initialized < 1) |
2a652f5a | 147 | return; |
6c8dbf00 | 148 | |
90c400bd | 149 | /* We do not acquire free_list_lock here because we completely |
29d79486 | 150 | reconstruct free_list in __malloc_fork_unlock_child. */ |
90c400bd | 151 | |
4bf5f222 | 152 | __libc_lock_lock (list_lock); |
7dac9f3d | 153 | |
8a727af9 | 154 | for (mstate ar_ptr = &main_arena;; ) |
6c8dbf00 | 155 | { |
4bf5f222 | 156 | __libc_lock_lock (ar_ptr->mutex); |
6c8dbf00 OB |
157 | ar_ptr = ar_ptr->next; |
158 | if (ar_ptr == &main_arena) | |
159 | break; | |
7dac9f3d | 160 | } |
fa8d436c UD |
161 | } |
162 | ||
29d79486 FW |
163 | void |
164 | __malloc_fork_unlock_parent (void) | |
fa8d436c | 165 | { |
6c8dbf00 | 166 | if (__malloc_initialized < 1) |
2a652f5a | 167 | return; |
6c8dbf00 | 168 | |
8a727af9 | 169 | for (mstate ar_ptr = &main_arena;; ) |
6c8dbf00 | 170 | { |
4bf5f222 | 171 | __libc_lock_unlock (ar_ptr->mutex); |
6c8dbf00 OB |
172 | ar_ptr = ar_ptr->next; |
173 | if (ar_ptr == &main_arena) | |
174 | break; | |
175 | } | |
4bf5f222 | 176 | __libc_lock_unlock (list_lock); |
fa8d436c UD |
177 | } |
178 | ||
29d79486 FW |
179 | void |
180 | __malloc_fork_unlock_child (void) | |
fa8d436c | 181 | { |
6c8dbf00 | 182 | if (__malloc_initialized < 1) |
2a652f5a | 183 | return; |
6c8dbf00 | 184 | |
8a727af9 | 185 | /* Push all arenas to the free list, except thread_arena, which is |
a62719ba | 186 | attached to the current thread. */ |
4bf5f222 | 187 | __libc_lock_init (free_list_lock); |
8a727af9 FW |
188 | if (thread_arena != NULL) |
189 | thread_arena->attached_threads = 1; | |
425ce2ed | 190 | free_list = NULL; |
8a727af9 | 191 | for (mstate ar_ptr = &main_arena;; ) |
6c8dbf00 | 192 | { |
4bf5f222 | 193 | __libc_lock_init (ar_ptr->mutex); |
8a727af9 | 194 | if (ar_ptr != thread_arena) |
6c8dbf00 | 195 | { |
a62719ba FW |
196 | /* This arena is no longer attached to any thread. */ |
197 | ar_ptr->attached_threads = 0; | |
6c8dbf00 OB |
198 | ar_ptr->next_free = free_list; |
199 | free_list = ar_ptr; | |
200 | } | |
201 | ar_ptr = ar_ptr->next; | |
202 | if (ar_ptr == &main_arena) | |
203 | break; | |
425ce2ed | 204 | } |
90c400bd | 205 | |
4bf5f222 | 206 | __libc_lock_init (list_lock); |
fa8d436c UD |
207 | } |
208 | ||
67e58f39 SP |
209 | #if HAVE_TUNABLES |
210 | static inline int do_set_mallopt_check (int32_t value); | |
211 | void | |
44330b6d | 212 | TUNABLE_CALLBACK (set_mallopt_check) (tunable_val_t *valp) |
67e58f39 | 213 | { |
8cbc826c | 214 | int32_t value = (int32_t) valp->numval; |
ac3ed168 | 215 | if (value != 0) |
67e58f39 SP |
216 | __malloc_check_init (); |
217 | } | |
218 | ||
44330b6d | 219 | # define TUNABLE_CALLBACK_FNDECL(__name, __type) \ |
67e58f39 SP |
220 | static inline int do_ ## __name (__type value); \ |
221 | void \ | |
44330b6d | 222 | TUNABLE_CALLBACK (__name) (tunable_val_t *valp) \ |
67e58f39 | 223 | { \ |
8cbc826c | 224 | __type value = (__type) (valp)->numval; \ |
67e58f39 SP |
225 | do_ ## __name (value); \ |
226 | } | |
227 | ||
44330b6d SP |
228 | TUNABLE_CALLBACK_FNDECL (set_mmap_threshold, size_t) |
229 | TUNABLE_CALLBACK_FNDECL (set_mmaps_max, int32_t) | |
230 | TUNABLE_CALLBACK_FNDECL (set_top_pad, size_t) | |
231 | TUNABLE_CALLBACK_FNDECL (set_perturb_byte, int32_t) | |
232 | TUNABLE_CALLBACK_FNDECL (set_trim_threshold, size_t) | |
233 | TUNABLE_CALLBACK_FNDECL (set_arena_max, size_t) | |
234 | TUNABLE_CALLBACK_FNDECL (set_arena_test, size_t) | |
d5c3fafc DD |
235 | #if USE_TCACHE |
236 | TUNABLE_CALLBACK_FNDECL (set_tcache_max, size_t) | |
237 | TUNABLE_CALLBACK_FNDECL (set_tcache_count, size_t) | |
238 | TUNABLE_CALLBACK_FNDECL (set_tcache_unsorted_limit, size_t) | |
239 | #endif | |
67e58f39 | 240 | #else |
fa8d436c | 241 | /* Initialization routine. */ |
fa8d436c UD |
242 | #include <string.h> |
243 | extern char **_environ; | |
244 | ||
245 | static char * | |
fa8d436c UD |
246 | next_env_entry (char ***position) |
247 | { | |
248 | char **current = *position; | |
249 | char *result = NULL; | |
250 | ||
251 | while (*current != NULL) | |
252 | { | |
253 | if (__builtin_expect ((*current)[0] == 'M', 0) | |
6c8dbf00 OB |
254 | && (*current)[1] == 'A' |
255 | && (*current)[2] == 'L' | |
256 | && (*current)[3] == 'L' | |
257 | && (*current)[4] == 'O' | |
258 | && (*current)[5] == 'C' | |
259 | && (*current)[6] == '_') | |
260 | { | |
261 | result = &(*current)[7]; | |
fa8d436c | 262 | |
6c8dbf00 OB |
263 | /* Save current position for next visit. */ |
264 | *position = ++current; | |
fa8d436c | 265 | |
6c8dbf00 OB |
266 | break; |
267 | } | |
fa8d436c UD |
268 | |
269 | ++current; | |
270 | } | |
271 | ||
272 | return result; | |
273 | } | |
67e58f39 | 274 | #endif |
fa8d436c | 275 | |
c0f62c56 | 276 | |
22a89187 | 277 | #ifdef SHARED |
c0f62c56 UD |
278 | static void * |
279 | __failing_morecore (ptrdiff_t d) | |
280 | { | |
281 | return (void *) MORECORE_FAILURE; | |
282 | } | |
5f21997b UD |
283 | |
284 | extern struct dl_open_hook *_dl_open_hook; | |
285 | libc_hidden_proto (_dl_open_hook); | |
fde89ad0 RM |
286 | #endif |
287 | ||
fa8d436c | 288 | static void |
06d6611a | 289 | ptmalloc_init (void) |
fa8d436c | 290 | { |
6c8dbf00 OB |
291 | if (__malloc_initialized >= 0) |
292 | return; | |
293 | ||
fa8d436c UD |
294 | __malloc_initialized = 0; |
295 | ||
22a89187 | 296 | #ifdef SHARED |
5f21997b UD |
297 | /* In case this libc copy is in a non-default namespace, never use brk. |
298 | Likewise if dlopened from statically linked program. */ | |
c0f62c56 UD |
299 | Dl_info di; |
300 | struct link_map *l; | |
5f21997b UD |
301 | |
302 | if (_dl_open_hook != NULL | |
303 | || (_dl_addr (ptmalloc_init, &di, &l, NULL) != 0 | |
6c8dbf00 | 304 | && l->l_ns != LM_ID_BASE)) |
c0f62c56 UD |
305 | __morecore = __failing_morecore; |
306 | #endif | |
307 | ||
6782806d | 308 | thread_arena = &main_arena; |
67e58f39 | 309 | |
3381be5c | 310 | malloc_init_state (&main_arena); |
67e58f39 | 311 | |
3381be5c | 312 | #if HAVE_TUNABLES |
44330b6d SP |
313 | TUNABLE_GET (check, int32_t, TUNABLE_CALLBACK (set_mallopt_check)); |
314 | TUNABLE_GET (top_pad, size_t, TUNABLE_CALLBACK (set_top_pad)); | |
315 | TUNABLE_GET (perturb, int32_t, TUNABLE_CALLBACK (set_perturb_byte)); | |
316 | TUNABLE_GET (mmap_threshold, size_t, TUNABLE_CALLBACK (set_mmap_threshold)); | |
317 | TUNABLE_GET (trim_threshold, size_t, TUNABLE_CALLBACK (set_trim_threshold)); | |
318 | TUNABLE_GET (mmap_max, int32_t, TUNABLE_CALLBACK (set_mmaps_max)); | |
319 | TUNABLE_GET (arena_max, size_t, TUNABLE_CALLBACK (set_arena_max)); | |
320 | TUNABLE_GET (arena_test, size_t, TUNABLE_CALLBACK (set_arena_test)); | |
3381be5c | 321 | # if USE_TCACHE |
d5c3fafc DD |
322 | TUNABLE_GET (tcache_max, size_t, TUNABLE_CALLBACK (set_tcache_max)); |
323 | TUNABLE_GET (tcache_count, size_t, TUNABLE_CALLBACK (set_tcache_count)); | |
324 | TUNABLE_GET (tcache_unsorted_limit, size_t, | |
325 | TUNABLE_CALLBACK (set_tcache_unsorted_limit)); | |
3381be5c | 326 | # endif |
67e58f39 | 327 | #else |
02d46fc4 | 328 | const char *s = NULL; |
a1ffb40e | 329 | if (__glibc_likely (_environ != NULL)) |
08e49216 RM |
330 | { |
331 | char **runp = _environ; | |
332 | char *envline; | |
333 | ||
334 | while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL, | |
6c8dbf00 OB |
335 | 0)) |
336 | { | |
337 | size_t len = strcspn (envline, "="); | |
338 | ||
339 | if (envline[len] != '=') | |
340 | /* This is a "MALLOC_" variable at the end of the string | |
341 | without a '=' character. Ignore it since otherwise we | |
342 | will access invalid memory below. */ | |
343 | continue; | |
344 | ||
345 | switch (len) | |
346 | { | |
347 | case 6: | |
348 | if (memcmp (envline, "CHECK_", 6) == 0) | |
349 | s = &envline[7]; | |
350 | break; | |
351 | case 8: | |
352 | if (!__builtin_expect (__libc_enable_secure, 0)) | |
353 | { | |
354 | if (memcmp (envline, "TOP_PAD_", 8) == 0) | |
355 | __libc_mallopt (M_TOP_PAD, atoi (&envline[9])); | |
356 | else if (memcmp (envline, "PERTURB_", 8) == 0) | |
357 | __libc_mallopt (M_PERTURB, atoi (&envline[9])); | |
358 | } | |
359 | break; | |
360 | case 9: | |
361 | if (!__builtin_expect (__libc_enable_secure, 0)) | |
362 | { | |
363 | if (memcmp (envline, "MMAP_MAX_", 9) == 0) | |
364 | __libc_mallopt (M_MMAP_MAX, atoi (&envline[10])); | |
365 | else if (memcmp (envline, "ARENA_MAX", 9) == 0) | |
366 | __libc_mallopt (M_ARENA_MAX, atoi (&envline[10])); | |
367 | } | |
368 | break; | |
369 | case 10: | |
370 | if (!__builtin_expect (__libc_enable_secure, 0)) | |
371 | { | |
372 | if (memcmp (envline, "ARENA_TEST", 10) == 0) | |
373 | __libc_mallopt (M_ARENA_TEST, atoi (&envline[11])); | |
374 | } | |
375 | break; | |
376 | case 15: | |
377 | if (!__builtin_expect (__libc_enable_secure, 0)) | |
378 | { | |
379 | if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0) | |
380 | __libc_mallopt (M_TRIM_THRESHOLD, atoi (&envline[16])); | |
381 | else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0) | |
382 | __libc_mallopt (M_MMAP_THRESHOLD, atoi (&envline[16])); | |
383 | } | |
384 | break; | |
385 | default: | |
386 | break; | |
387 | } | |
388 | } | |
389 | } | |
ac3ed168 FW |
390 | if (s && s[0] != '\0' && s[0] != '0') |
391 | __malloc_check_init (); | |
67e58f39 SP |
392 | #endif |
393 | ||
2ba3cfa1 | 394 | #if HAVE_MALLOC_INIT_HOOK |
92e1ab0e | 395 | void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook); |
df77455c UD |
396 | if (hook != NULL) |
397 | (*hook)(); | |
2ba3cfa1 | 398 | #endif |
fa8d436c UD |
399 | __malloc_initialized = 1; |
400 | } | |
401 | ||
fa8d436c UD |
402 | /* Managing heaps and arenas (for concurrent threads) */ |
403 | ||
fa8d436c UD |
404 | #if MALLOC_DEBUG > 1 |
405 | ||
406 | /* Print the complete contents of a single heap to stderr. */ | |
407 | ||
408 | static void | |
6c8dbf00 | 409 | dump_heap (heap_info *heap) |
fa8d436c UD |
410 | { |
411 | char *ptr; | |
412 | mchunkptr p; | |
413 | ||
6c8dbf00 OB |
414 | fprintf (stderr, "Heap %p, size %10lx:\n", heap, (long) heap->size); |
415 | ptr = (heap->ar_ptr != (mstate) (heap + 1)) ? | |
416 | (char *) (heap + 1) : (char *) (heap + 1) + sizeof (struct malloc_state); | |
417 | p = (mchunkptr) (((unsigned long) ptr + MALLOC_ALIGN_MASK) & | |
418 | ~MALLOC_ALIGN_MASK); | |
419 | for (;; ) | |
420 | { | |
421 | fprintf (stderr, "chunk %p size %10lx", p, (long) p->size); | |
422 | if (p == top (heap->ar_ptr)) | |
423 | { | |
424 | fprintf (stderr, " (top)\n"); | |
425 | break; | |
426 | } | |
427 | else if (p->size == (0 | PREV_INUSE)) | |
428 | { | |
429 | fprintf (stderr, " (fence)\n"); | |
430 | break; | |
431 | } | |
432 | fprintf (stderr, "\n"); | |
433 | p = next_chunk (p); | |
fa8d436c | 434 | } |
fa8d436c | 435 | } |
fa8d436c UD |
436 | #endif /* MALLOC_DEBUG > 1 */ |
437 | ||
26d550d3 UD |
438 | /* If consecutive mmap (0, HEAP_MAX_SIZE << 1, ...) calls return decreasing |
439 | addresses as opposed to increasing, new_heap would badly fragment the | |
440 | address space. In that case remember the second HEAP_MAX_SIZE part | |
441 | aligned to HEAP_MAX_SIZE from last mmap (0, HEAP_MAX_SIZE << 1, ...) | |
442 | call (if it is already aligned) and try to reuse it next time. We need | |
443 | no locking for it, as kernel ensures the atomicity for us - worst case | |
444 | we'll call mmap (addr, HEAP_MAX_SIZE, ...) for some value of addr in | |
445 | multiple threads, but only one will succeed. */ | |
446 | static char *aligned_heap_area; | |
447 | ||
fa8d436c UD |
448 | /* Create a new heap. size is automatically rounded up to a multiple |
449 | of the page size. */ | |
450 | ||
451 | static heap_info * | |
6c8dbf00 | 452 | new_heap (size_t size, size_t top_pad) |
fa8d436c | 453 | { |
8a35c3fe | 454 | size_t pagesize = GLRO (dl_pagesize); |
fa8d436c UD |
455 | char *p1, *p2; |
456 | unsigned long ul; | |
457 | heap_info *h; | |
458 | ||
6c8dbf00 | 459 | if (size + top_pad < HEAP_MIN_SIZE) |
fa8d436c | 460 | size = HEAP_MIN_SIZE; |
6c8dbf00 | 461 | else if (size + top_pad <= HEAP_MAX_SIZE) |
fa8d436c | 462 | size += top_pad; |
6c8dbf00 | 463 | else if (size > HEAP_MAX_SIZE) |
fa8d436c UD |
464 | return 0; |
465 | else | |
466 | size = HEAP_MAX_SIZE; | |
8a35c3fe | 467 | size = ALIGN_UP (size, pagesize); |
fa8d436c UD |
468 | |
469 | /* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed. | |
470 | No swap space needs to be reserved for the following large | |
471 | mapping (on Linux, this is the case for all non-writable mappings | |
472 | anyway). */ | |
26d550d3 | 473 | p2 = MAP_FAILED; |
6c8dbf00 OB |
474 | if (aligned_heap_area) |
475 | { | |
476 | p2 = (char *) MMAP (aligned_heap_area, HEAP_MAX_SIZE, PROT_NONE, | |
477 | MAP_NORESERVE); | |
478 | aligned_heap_area = NULL; | |
479 | if (p2 != MAP_FAILED && ((unsigned long) p2 & (HEAP_MAX_SIZE - 1))) | |
480 | { | |
481 | __munmap (p2, HEAP_MAX_SIZE); | |
482 | p2 = MAP_FAILED; | |
483 | } | |
26d550d3 | 484 | } |
6c8dbf00 OB |
485 | if (p2 == MAP_FAILED) |
486 | { | |
487 | p1 = (char *) MMAP (0, HEAP_MAX_SIZE << 1, PROT_NONE, MAP_NORESERVE); | |
488 | if (p1 != MAP_FAILED) | |
489 | { | |
490 | p2 = (char *) (((unsigned long) p1 + (HEAP_MAX_SIZE - 1)) | |
491 | & ~(HEAP_MAX_SIZE - 1)); | |
492 | ul = p2 - p1; | |
493 | if (ul) | |
494 | __munmap (p1, ul); | |
495 | else | |
496 | aligned_heap_area = p2 + HEAP_MAX_SIZE; | |
497 | __munmap (p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul); | |
498 | } | |
26d550d3 | 499 | else |
6c8dbf00 OB |
500 | { |
501 | /* Try to take the chance that an allocation of only HEAP_MAX_SIZE | |
502 | is already aligned. */ | |
503 | p2 = (char *) MMAP (0, HEAP_MAX_SIZE, PROT_NONE, MAP_NORESERVE); | |
504 | if (p2 == MAP_FAILED) | |
505 | return 0; | |
506 | ||
507 | if ((unsigned long) p2 & (HEAP_MAX_SIZE - 1)) | |
508 | { | |
509 | __munmap (p2, HEAP_MAX_SIZE); | |
510 | return 0; | |
511 | } | |
512 | } | |
fa8d436c | 513 | } |
6c8dbf00 OB |
514 | if (__mprotect (p2, size, PROT_READ | PROT_WRITE) != 0) |
515 | { | |
516 | __munmap (p2, HEAP_MAX_SIZE); | |
517 | return 0; | |
518 | } | |
519 | h = (heap_info *) p2; | |
fa8d436c | 520 | h->size = size; |
c7fd3362 | 521 | h->mprotect_size = size; |
322dea08 | 522 | LIBC_PROBE (memory_heap_new, 2, h, h->size); |
fa8d436c UD |
523 | return h; |
524 | } | |
525 | ||
cbf5760e UD |
526 | /* Grow a heap. size is automatically rounded up to a |
527 | multiple of the page size. */ | |
fa8d436c UD |
528 | |
529 | static int | |
6c8dbf00 | 530 | grow_heap (heap_info *h, long diff) |
fa8d436c | 531 | { |
8a35c3fe | 532 | size_t pagesize = GLRO (dl_pagesize); |
fa8d436c UD |
533 | long new_size; |
534 | ||
8a35c3fe | 535 | diff = ALIGN_UP (diff, pagesize); |
6c8dbf00 OB |
536 | new_size = (long) h->size + diff; |
537 | if ((unsigned long) new_size > (unsigned long) HEAP_MAX_SIZE) | |
cbf5760e | 538 | return -1; |
6c8dbf00 OB |
539 | |
540 | if ((unsigned long) new_size > h->mprotect_size) | |
541 | { | |
542 | if (__mprotect ((char *) h + h->mprotect_size, | |
543 | (unsigned long) new_size - h->mprotect_size, | |
544 | PROT_READ | PROT_WRITE) != 0) | |
545 | return -2; | |
546 | ||
547 | h->mprotect_size = new_size; | |
548 | } | |
cbf5760e UD |
549 | |
550 | h->size = new_size; | |
322dea08 | 551 | LIBC_PROBE (memory_heap_more, 2, h, h->size); |
cbf5760e UD |
552 | return 0; |
553 | } | |
554 | ||
555 | /* Shrink a heap. */ | |
556 | ||
557 | static int | |
6c8dbf00 | 558 | shrink_heap (heap_info *h, long diff) |
cbf5760e UD |
559 | { |
560 | long new_size; | |
561 | ||
6c8dbf00 OB |
562 | new_size = (long) h->size - diff; |
563 | if (new_size < (long) sizeof (*h)) | |
cbf5760e | 564 | return -1; |
6c8dbf00 | 565 | |
9fab36eb SP |
566 | /* Try to re-map the extra heap space freshly to save memory, and make it |
567 | inaccessible. See malloc-sysdep.h to know when this is true. */ | |
a1ffb40e | 568 | if (__glibc_unlikely (check_may_shrink_heap ())) |
cbf5760e | 569 | { |
6c8dbf00 OB |
570 | if ((char *) MMAP ((char *) h + new_size, diff, PROT_NONE, |
571 | MAP_FIXED) == (char *) MAP_FAILED) | |
572 | return -2; | |
573 | ||
cbf5760e UD |
574 | h->mprotect_size = new_size; |
575 | } | |
cbf5760e | 576 | else |
6c8dbf00 | 577 | __madvise ((char *) h + new_size, diff, MADV_DONTNEED); |
cbf5760e UD |
578 | /*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/ |
579 | ||
fa8d436c | 580 | h->size = new_size; |
322dea08 | 581 | LIBC_PROBE (memory_heap_less, 2, h, h->size); |
fa8d436c UD |
582 | return 0; |
583 | } | |
584 | ||
585 | /* Delete a heap. */ | |
586 | ||
26d550d3 | 587 | #define delete_heap(heap) \ |
6c8dbf00 OB |
588 | do { \ |
589 | if ((char *) (heap) + HEAP_MAX_SIZE == aligned_heap_area) \ | |
590 | aligned_heap_area = NULL; \ | |
591 | __munmap ((char *) (heap), HEAP_MAX_SIZE); \ | |
592 | } while (0) | |
fa8d436c UD |
593 | |
594 | static int | |
6c8dbf00 | 595 | heap_trim (heap_info *heap, size_t pad) |
fa8d436c UD |
596 | { |
597 | mstate ar_ptr = heap->ar_ptr; | |
6c8dbf00 OB |
598 | unsigned long pagesz = GLRO (dl_pagesize); |
599 | mchunkptr top_chunk = top (ar_ptr), p, bck, fwd; | |
fa8d436c | 600 | heap_info *prev_heap; |
c26efef9 | 601 | long new_size, top_size, top_area, extra, prev_size, misalign; |
fa8d436c UD |
602 | |
603 | /* Can this heap go away completely? */ | |
6c8dbf00 OB |
604 | while (top_chunk == chunk_at_offset (heap, sizeof (*heap))) |
605 | { | |
606 | prev_heap = heap->prev; | |
607 | prev_size = prev_heap->size - (MINSIZE - 2 * SIZE_SZ); | |
608 | p = chunk_at_offset (prev_heap, prev_size); | |
609 | /* fencepost must be properly aligned. */ | |
610 | misalign = ((long) p) & MALLOC_ALIGN_MASK; | |
611 | p = chunk_at_offset (prev_heap, prev_size - misalign); | |
e9c4fe93 | 612 | assert (chunksize_nomask (p) == (0 | PREV_INUSE)); /* must be fencepost */ |
6c8dbf00 OB |
613 | p = prev_chunk (p); |
614 | new_size = chunksize (p) + (MINSIZE - 2 * SIZE_SZ) + misalign; | |
615 | assert (new_size > 0 && new_size < (long) (2 * MINSIZE)); | |
616 | if (!prev_inuse (p)) | |
e9c4fe93 | 617 | new_size += prev_size (p); |
6c8dbf00 OB |
618 | assert (new_size > 0 && new_size < HEAP_MAX_SIZE); |
619 | if (new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz) | |
620 | break; | |
621 | ar_ptr->system_mem -= heap->size; | |
6c8dbf00 OB |
622 | LIBC_PROBE (memory_heap_free, 2, heap, heap->size); |
623 | delete_heap (heap); | |
624 | heap = prev_heap; | |
625 | if (!prev_inuse (p)) /* consolidate backward */ | |
626 | { | |
627 | p = prev_chunk (p); | |
fff94fa2 | 628 | unlink (ar_ptr, p, bck, fwd); |
6c8dbf00 OB |
629 | } |
630 | assert (((unsigned long) ((char *) p + new_size) & (pagesz - 1)) == 0); | |
631 | assert (((char *) p + new_size) == ((char *) heap + heap->size)); | |
632 | top (ar_ptr) = top_chunk = p; | |
633 | set_head (top_chunk, new_size | PREV_INUSE); | |
634 | /*check_chunk(ar_ptr, top_chunk);*/ | |
fa8d436c | 635 | } |
c26efef9 MG |
636 | |
637 | /* Uses similar logic for per-thread arenas as the main arena with systrim | |
e4bc326d CD |
638 | and _int_free by preserving the top pad and rounding down to the nearest |
639 | page. */ | |
6c8dbf00 | 640 | top_size = chunksize (top_chunk); |
e4bc326d CD |
641 | if ((unsigned long)(top_size) < |
642 | (unsigned long)(mp_.trim_threshold)) | |
643 | return 0; | |
644 | ||
c26efef9 | 645 | top_area = top_size - MINSIZE - 1; |
f8ef472c | 646 | if (top_area < 0 || (size_t) top_area <= pad) |
c26efef9 MG |
647 | return 0; |
648 | ||
e4bc326d | 649 | /* Release in pagesize units and round down to the nearest page. */ |
c26efef9 | 650 | extra = ALIGN_DOWN(top_area - pad, pagesz); |
e4bc326d | 651 | if (extra == 0) |
fa8d436c | 652 | return 0; |
6c8dbf00 | 653 | |
fa8d436c | 654 | /* Try to shrink. */ |
6c8dbf00 | 655 | if (shrink_heap (heap, extra) != 0) |
fa8d436c | 656 | return 0; |
6c8dbf00 | 657 | |
fa8d436c | 658 | ar_ptr->system_mem -= extra; |
fa8d436c UD |
659 | |
660 | /* Success. Adjust top accordingly. */ | |
6c8dbf00 | 661 | set_head (top_chunk, (top_size - extra) | PREV_INUSE); |
fa8d436c UD |
662 | /*check_chunk(ar_ptr, top_chunk);*/ |
663 | return 1; | |
664 | } | |
665 | ||
04ec80e4 UD |
666 | /* Create a new arena with initial size "size". */ |
667 | ||
a62719ba | 668 | /* If REPLACED_ARENA is not NULL, detach it from this thread. Must be |
90c400bd | 669 | called while free_list_lock is held. */ |
a62719ba FW |
670 | static void |
671 | detach_arena (mstate replaced_arena) | |
672 | { | |
673 | if (replaced_arena != NULL) | |
674 | { | |
675 | assert (replaced_arena->attached_threads > 0); | |
676 | /* The current implementation only detaches from main_arena in | |
677 | case of allocation failure. This means that it is likely not | |
678 | beneficial to put the arena on free_list even if the | |
679 | reference count reaches zero. */ | |
680 | --replaced_arena->attached_threads; | |
681 | } | |
682 | } | |
683 | ||
04ec80e4 | 684 | static mstate |
6c8dbf00 | 685 | _int_new_arena (size_t size) |
04ec80e4 UD |
686 | { |
687 | mstate a; | |
688 | heap_info *h; | |
689 | char *ptr; | |
690 | unsigned long misalign; | |
691 | ||
6c8dbf00 OB |
692 | h = new_heap (size + (sizeof (*h) + sizeof (*a) + MALLOC_ALIGNMENT), |
693 | mp_.top_pad); | |
694 | if (!h) | |
695 | { | |
696 | /* Maybe size is too large to fit in a single heap. So, just try | |
697 | to create a minimally-sized arena and let _int_malloc() attempt | |
698 | to deal with the large request via mmap_chunk(). */ | |
699 | h = new_heap (sizeof (*h) + sizeof (*a) + MALLOC_ALIGNMENT, mp_.top_pad); | |
700 | if (!h) | |
701 | return 0; | |
702 | } | |
703 | a = h->ar_ptr = (mstate) (h + 1); | |
704 | malloc_init_state (a); | |
a62719ba | 705 | a->attached_threads = 1; |
04ec80e4 UD |
706 | /*a->next = NULL;*/ |
707 | a->system_mem = a->max_system_mem = h->size; | |
04ec80e4 UD |
708 | |
709 | /* Set up the top chunk, with proper alignment. */ | |
6c8dbf00 OB |
710 | ptr = (char *) (a + 1); |
711 | misalign = (unsigned long) chunk2mem (ptr) & MALLOC_ALIGN_MASK; | |
04ec80e4 UD |
712 | if (misalign > 0) |
713 | ptr += MALLOC_ALIGNMENT - misalign; | |
6c8dbf00 OB |
714 | top (a) = (mchunkptr) ptr; |
715 | set_head (top (a), (((char *) h + h->size) - ptr) | PREV_INUSE); | |
04ec80e4 | 716 | |
3ea5be54 | 717 | LIBC_PROBE (memory_arena_new, 2, a, size); |
a62719ba | 718 | mstate replaced_arena = thread_arena; |
6782806d | 719 | thread_arena = a; |
4bf5f222 | 720 | __libc_lock_init (a->mutex); |
425ce2ed | 721 | |
4bf5f222 | 722 | __libc_lock_lock (list_lock); |
425ce2ed UD |
723 | |
724 | /* Add the new arena to the global list. */ | |
725 | a->next = main_arena.next; | |
90c400bd FW |
726 | /* FIXME: The barrier is an attempt to synchronize with read access |
727 | in reused_arena, which does not acquire list_lock while | |
728 | traversing the list. */ | |
425ce2ed UD |
729 | atomic_write_barrier (); |
730 | main_arena.next = a; | |
731 | ||
4bf5f222 | 732 | __libc_lock_unlock (list_lock); |
425ce2ed | 733 | |
4bf5f222 | 734 | __libc_lock_lock (free_list_lock); |
90c400bd | 735 | detach_arena (replaced_arena); |
4bf5f222 | 736 | __libc_lock_unlock (free_list_lock); |
90c400bd FW |
737 | |
738 | /* Lock this arena. NB: Another thread may have been attached to | |
739 | this arena because the arena is now accessible from the | |
740 | main_arena.next list and could have been picked by reused_arena. | |
741 | This can only happen for the last arena created (before the arena | |
742 | limit is reached). At this point, some arena has to be attached | |
743 | to two threads. We could acquire the arena lock before list_lock | |
744 | to make it less likely that reused_arena picks this new arena, | |
29d79486 FW |
745 | but this could result in a deadlock with |
746 | __malloc_fork_lock_parent. */ | |
90c400bd | 747 | |
4bf5f222 | 748 | __libc_lock_lock (a->mutex); |
90c400bd | 749 | |
04ec80e4 UD |
750 | return a; |
751 | } | |
752 | ||
425ce2ed | 753 | |
f88aab5d | 754 | /* Remove an arena from free_list. */ |
425ce2ed UD |
755 | static mstate |
756 | get_free_list (void) | |
757 | { | |
a62719ba | 758 | mstate replaced_arena = thread_arena; |
425ce2ed UD |
759 | mstate result = free_list; |
760 | if (result != NULL) | |
761 | { | |
4bf5f222 | 762 | __libc_lock_lock (free_list_lock); |
425ce2ed UD |
763 | result = free_list; |
764 | if (result != NULL) | |
a62719ba FW |
765 | { |
766 | free_list = result->next_free; | |
767 | ||
3da825ce | 768 | /* The arena will be attached to this thread. */ |
f88aab5d FW |
769 | assert (result->attached_threads == 0); |
770 | result->attached_threads = 1; | |
a62719ba FW |
771 | |
772 | detach_arena (replaced_arena); | |
773 | } | |
4bf5f222 | 774 | __libc_lock_unlock (free_list_lock); |
425ce2ed UD |
775 | |
776 | if (result != NULL) | |
6c8dbf00 OB |
777 | { |
778 | LIBC_PROBE (memory_arena_reuse_free_list, 1, result); | |
4bf5f222 | 779 | __libc_lock_lock (result->mutex); |
6782806d | 780 | thread_arena = result; |
6c8dbf00 | 781 | } |
425ce2ed UD |
782 | } |
783 | ||
784 | return result; | |
785 | } | |
786 | ||
f88aab5d FW |
787 | /* Remove the arena from the free list (if it is present). |
788 | free_list_lock must have been acquired by the caller. */ | |
789 | static void | |
790 | remove_from_free_list (mstate arena) | |
791 | { | |
792 | mstate *previous = &free_list; | |
793 | for (mstate p = free_list; p != NULL; p = p->next_free) | |
794 | { | |
795 | assert (p->attached_threads == 0); | |
796 | if (p == arena) | |
797 | { | |
798 | /* Remove the requested arena from the list. */ | |
799 | *previous = p->next_free; | |
800 | break; | |
801 | } | |
802 | else | |
803 | previous = &p->next_free; | |
804 | } | |
805 | } | |
806 | ||
77480c6b | 807 | /* Lock and return an arena that can be reused for memory allocation. |
bf51f568 JL |
808 | Avoid AVOID_ARENA as we have already failed to allocate memory in |
809 | it and it is currently locked. */ | |
425ce2ed | 810 | static mstate |
bf51f568 | 811 | reused_arena (mstate avoid_arena) |
425ce2ed | 812 | { |
425ce2ed | 813 | mstate result; |
90c400bd | 814 | /* FIXME: Access to next_to_use suffers from data races. */ |
425ce2ed UD |
815 | static mstate next_to_use; |
816 | if (next_to_use == NULL) | |
817 | next_to_use = &main_arena; | |
818 | ||
3da825ce FW |
819 | /* Iterate over all arenas (including those linked from |
820 | free_list). */ | |
425ce2ed UD |
821 | result = next_to_use; |
822 | do | |
823 | { | |
a9da0bb2 | 824 | if (!__libc_lock_trylock (result->mutex)) |
6c8dbf00 | 825 | goto out; |
425ce2ed | 826 | |
90c400bd | 827 | /* FIXME: This is a data race, see _int_new_arena. */ |
425ce2ed UD |
828 | result = result->next; |
829 | } | |
830 | while (result != next_to_use); | |
831 | ||
bf51f568 JL |
832 | /* Avoid AVOID_ARENA as we have already failed to allocate memory |
833 | in that arena and it is currently locked. */ | |
834 | if (result == avoid_arena) | |
835 | result = result->next; | |
836 | ||
fff94fa2 | 837 | /* No arena available without contention. Wait for the next in line. */ |
6999d38c | 838 | LIBC_PROBE (memory_arena_reuse_wait, 3, &result->mutex, result, avoid_arena); |
4bf5f222 | 839 | __libc_lock_lock (result->mutex); |
425ce2ed | 840 | |
6c8dbf00 | 841 | out: |
f88aab5d | 842 | /* Attach the arena to the current thread. */ |
a62719ba | 843 | { |
90c400bd | 844 | /* Update the arena thread attachment counters. */ |
a62719ba | 845 | mstate replaced_arena = thread_arena; |
4bf5f222 | 846 | __libc_lock_lock (free_list_lock); |
a62719ba | 847 | detach_arena (replaced_arena); |
f88aab5d FW |
848 | |
849 | /* We may have picked up an arena on the free list. We need to | |
850 | preserve the invariant that no arena on the free list has a | |
851 | positive attached_threads counter (otherwise, | |
852 | arena_thread_freeres cannot use the counter to determine if the | |
853 | arena needs to be put on the free list). We unconditionally | |
854 | remove the selected arena from the free list. The caller of | |
855 | reused_arena checked the free list and observed it to be empty, | |
856 | so the list is very short. */ | |
857 | remove_from_free_list (result); | |
858 | ||
a62719ba | 859 | ++result->attached_threads; |
f88aab5d | 860 | |
4bf5f222 | 861 | __libc_lock_unlock (free_list_lock); |
a62719ba FW |
862 | } |
863 | ||
6999d38c | 864 | LIBC_PROBE (memory_arena_reuse, 2, result, avoid_arena); |
6782806d | 865 | thread_arena = result; |
425ce2ed UD |
866 | next_to_use = result->next; |
867 | ||
868 | return result; | |
869 | } | |
425ce2ed | 870 | |
fa8d436c | 871 | static mstate |
92a9b22d | 872 | arena_get2 (size_t size, mstate avoid_arena) |
fa8d436c UD |
873 | { |
874 | mstate a; | |
fa8d436c | 875 | |
77cdc054 AS |
876 | static size_t narenas_limit; |
877 | ||
878 | a = get_free_list (); | |
879 | if (a == NULL) | |
880 | { | |
881 | /* Nothing immediately available, so generate a new arena. */ | |
882 | if (narenas_limit == 0) | |
6c8dbf00 OB |
883 | { |
884 | if (mp_.arena_max != 0) | |
885 | narenas_limit = mp_.arena_max; | |
886 | else if (narenas > mp_.arena_test) | |
887 | { | |
888 | int n = __get_nprocs (); | |
889 | ||
890 | if (n >= 1) | |
891 | narenas_limit = NARENAS_FROM_NCORES (n); | |
892 | else | |
893 | /* We have no information about the system. Assume two | |
894 | cores. */ | |
895 | narenas_limit = NARENAS_FROM_NCORES (2); | |
896 | } | |
897 | } | |
77cdc054 AS |
898 | repeat:; |
899 | size_t n = narenas; | |
41b81892 | 900 | /* NB: the following depends on the fact that (size_t)0 - 1 is a |
6c8dbf00 OB |
901 | very large number and that the underflow is OK. If arena_max |
902 | is set the value of arena_test is irrelevant. If arena_test | |
903 | is set but narenas is not yet larger or equal to arena_test | |
904 | narenas_limit is 0. There is no possibility for narenas to | |
905 | be too big for the test to always fail since there is not | |
906 | enough address space to create that many arenas. */ | |
a1ffb40e | 907 | if (__glibc_unlikely (n <= narenas_limit - 1)) |
6c8dbf00 OB |
908 | { |
909 | if (catomic_compare_and_exchange_bool_acq (&narenas, n + 1, n)) | |
910 | goto repeat; | |
911 | a = _int_new_arena (size); | |
a1ffb40e | 912 | if (__glibc_unlikely (a == NULL)) |
6c8dbf00 OB |
913 | catomic_decrement (&narenas); |
914 | } | |
a5fb313c | 915 | else |
6c8dbf00 | 916 | a = reused_arena (avoid_arena); |
77cdc054 | 917 | } |
fa8d436c UD |
918 | return a; |
919 | } | |
920 | ||
c78ab094 SP |
921 | /* If we don't have the main arena, then maybe the failure is due to running |
922 | out of mmapped areas, so we can try allocating on the main arena. | |
923 | Otherwise, it is likely that sbrk() has failed and there is still a chance | |
924 | to mmap(), so try one of the other arenas. */ | |
925 | static mstate | |
926 | arena_get_retry (mstate ar_ptr, size_t bytes) | |
927 | { | |
655673f3 | 928 | LIBC_PROBE (memory_arena_retry, 2, bytes, ar_ptr); |
6c8dbf00 OB |
929 | if (ar_ptr != &main_arena) |
930 | { | |
4bf5f222 | 931 | __libc_lock_unlock (ar_ptr->mutex); |
6c8dbf00 | 932 | ar_ptr = &main_arena; |
4bf5f222 | 933 | __libc_lock_lock (ar_ptr->mutex); |
6c8dbf00 OB |
934 | } |
935 | else | |
936 | { | |
4bf5f222 | 937 | __libc_lock_unlock (ar_ptr->mutex); |
92a9b22d | 938 | ar_ptr = arena_get2 (bytes, ar_ptr); |
6c8dbf00 | 939 | } |
c78ab094 SP |
940 | |
941 | return ar_ptr; | |
942 | } | |
943 | ||
425ce2ed UD |
944 | static void __attribute__ ((section ("__libc_thread_freeres_fn"))) |
945 | arena_thread_freeres (void) | |
946 | { | |
6782806d FW |
947 | mstate a = thread_arena; |
948 | thread_arena = NULL; | |
425ce2ed UD |
949 | |
950 | if (a != NULL) | |
951 | { | |
4bf5f222 | 952 | __libc_lock_lock (free_list_lock); |
a62719ba FW |
953 | /* If this was the last attached thread for this arena, put the |
954 | arena on the free list. */ | |
955 | assert (a->attached_threads > 0); | |
956 | if (--a->attached_threads == 0) | |
957 | { | |
958 | a->next_free = free_list; | |
959 | free_list = a; | |
960 | } | |
4bf5f222 | 961 | __libc_lock_unlock (free_list_lock); |
425ce2ed UD |
962 | } |
963 | } | |
964 | text_set_element (__libc_thread_subfreeres, arena_thread_freeres); | |
425ce2ed | 965 | |
fa8d436c UD |
966 | /* |
967 | * Local variables: | |
968 | * c-basic-offset: 2 | |
969 | * End: | |
970 | */ |