1 /* Malloc implementation for multiple threads without lock contention.
2 Copyright (C) 2001,2002,2003,2004,2005,2006,2007,2009,2010,2011,2012
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5 Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation; either version 2.1 of the
10 License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; see the file COPYING.LIB. If not,
19 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 /* Compile-time constants. */
26 #define HEAP_MIN_SIZE (32*1024)
28 # ifdef DEFAULT_MMAP_THRESHOLD_MAX
29 # define HEAP_MAX_SIZE (2 * DEFAULT_MMAP_THRESHOLD_MAX)
31 # define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */
35 /* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps
36 that are dynamically created for multi-threaded programs. The
37 maximum size must be a power of two, for fast determination of
38 which heap belongs to a chunk. It should be much larger than the
39 mmap threshold, so that requests with a size just below that
40 threshold can be fulfilled without creating too many heaps. */
44 #define THREAD_STATS 0
47 /* If THREAD_STATS is non-zero, some statistics on mutex locking are
50 /***************************************************************************/
52 #define top(ar_ptr) ((ar_ptr)->top)
54 /* A heap is a single contiguous memory region holding (coalesceable)
55 malloc_chunks. It is allocated with mmap() and always starts at an
56 address aligned to HEAP_MAX_SIZE. */
58 typedef struct _heap_info {
59 mstate ar_ptr; /* Arena for this heap. */
60 struct _heap_info *prev; /* Previous heap. */
61 size_t size; /* Current size in bytes. */
62 size_t mprotect_size; /* Size in bytes that has been mprotected
63 PROT_READ|PROT_WRITE. */
64 /* Make sure the following data is properly aligned, particularly
65 that sizeof (heap_info) + 2 * SIZE_SZ is a multiple of
67 char pad[-6 * SIZE_SZ & MALLOC_ALIGN_MASK];
70 /* Get a compile-time error if the heap_info padding is not correct
71 to make alignment work as expected in sYSMALLOc. */
72 extern int sanity_check_heap_info_alignment[(sizeof (heap_info)
73 + 2 * SIZE_SZ) % MALLOC_ALIGNMENT
76 /* Thread specific data */
78 static tsd_key_t arena_key;
79 static mutex_t list_lock = MUTEX_INITIALIZER;
81 static size_t narenas = 1;
82 static mstate free_list;
86 static int stat_n_heaps;
87 #define THREAD_STAT(x) x
89 #define THREAD_STAT(x) do ; while(0)
92 /* Mapped memory in non-main arenas (reliable only for NO_THREADS). */
93 static unsigned long arena_mem;
95 /* Already initialized? */
96 int __malloc_initialized = -1;
98 /**************************************************************************/
101 /* arena_get() acquires an arena and locks the corresponding mutex.
102 First, try the one last locked successfully by this thread. (This
103 is the common case and handled with a macro for speed.) Then, loop
104 once over the circularly linked list of arenas. If no arena is
105 readily available, create a new one. In this latter case, `size'
106 is just a hint as to how much memory will be required immediately
109 #define arena_get(ptr, size) do { \
111 arena_lock(ptr, size); \
114 #define arena_lookup(ptr) do { \
116 ptr = (mstate)tsd_getspecific(arena_key, vptr); \
120 # define arena_lock(ptr, size) do { \
122 (void)mutex_lock(&ptr->mutex); \
124 ptr = arena_get2(ptr, (size)); \
127 # define arena_lock(ptr, size) do { \
128 if(ptr && !mutex_trylock(&ptr->mutex)) { \
129 THREAD_STAT(++(ptr->stat_lock_direct)); \
131 ptr = arena_get2(ptr, (size)); \
135 /* find the heap and corresponding arena for a given ptr */
137 #define heap_for_ptr(ptr) \
138 ((heap_info *)((unsigned long)(ptr) & ~(HEAP_MAX_SIZE-1)))
139 #define arena_for_chunk(ptr) \
140 (chunk_non_main_arena(ptr) ? heap_for_ptr(ptr)->ar_ptr : &main_arena)
143 /**************************************************************************/
145 /* atfork support. */
147 static __malloc_ptr_t (*save_malloc_hook) (size_t __size,
148 const __malloc_ptr_t);
149 static void (*save_free_hook) (__malloc_ptr_t __ptr,
150 const __malloc_ptr_t);
151 static void* save_arena;
157 /* Magic value for the thread-specific arena pointer when
158 malloc_atfork() is in use. */
160 #define ATFORK_ARENA_PTR ((void*)-1)
162 /* The following hooks are used while the `atfork' handling mechanism
166 malloc_atfork(size_t sz, const void *caller)
171 tsd_getspecific(arena_key, vptr);
172 if(vptr == ATFORK_ARENA_PTR) {
173 /* We are the only thread that may allocate at all. */
174 if(save_malloc_hook != malloc_check) {
175 return _int_malloc(&main_arena, sz);
179 victim = _int_malloc(&main_arena, sz+1);
180 return mem2mem_check(victim, sz);
183 /* Suspend the thread until the `atfork' handlers have completed.
184 By that time, the hooks will have been reset as well, so that
185 mALLOc() can be used again. */
186 (void)mutex_lock(&list_lock);
187 (void)mutex_unlock(&list_lock);
188 return public_mALLOc(sz);
193 free_atfork(void* mem, const void *caller)
197 mchunkptr p; /* chunk corresponding to mem */
199 if (mem == 0) /* free(0) has no effect */
202 p = mem2chunk(mem); /* do not bother to replicate free_check here */
204 if (chunk_is_mmapped(p)) /* release mmapped memory. */
210 ar_ptr = arena_for_chunk(p);
211 tsd_getspecific(arena_key, vptr);
212 _int_free(ar_ptr, p, vptr == ATFORK_ARENA_PTR);
216 /* Counter for number of times the list is locked by the same thread. */
217 static unsigned int atfork_recursive_cntr;
219 /* The following two functions are registered via thread_atfork() to
220 make sure that the mutexes remain in a consistent state in the
221 fork()ed version of a thread. Also adapt the malloc and free hooks
222 temporarily, because the `atfork' handler mechanism may use
223 malloc/free internally (e.g. in LinuxThreads). */
226 ptmalloc_lock_all (void)
230 if(__malloc_initialized < 1)
232 if (mutex_trylock(&list_lock))
235 tsd_getspecific(arena_key, my_arena);
236 if (my_arena == ATFORK_ARENA_PTR)
237 /* This is the same thread which already locks the global list.
238 Just bump the counter. */
241 /* This thread has to wait its turn. */
242 (void)mutex_lock(&list_lock);
244 for(ar_ptr = &main_arena;;) {
245 (void)mutex_lock(&ar_ptr->mutex);
246 ar_ptr = ar_ptr->next;
247 if(ar_ptr == &main_arena) break;
249 save_malloc_hook = __malloc_hook;
250 save_free_hook = __free_hook;
251 __malloc_hook = malloc_atfork;
252 __free_hook = free_atfork;
253 /* Only the current thread may perform malloc/free calls now. */
254 tsd_getspecific(arena_key, save_arena);
255 tsd_setspecific(arena_key, ATFORK_ARENA_PTR);
257 ++atfork_recursive_cntr;
261 ptmalloc_unlock_all (void)
265 if(__malloc_initialized < 1)
267 if (--atfork_recursive_cntr != 0)
269 tsd_setspecific(arena_key, save_arena);
270 __malloc_hook = save_malloc_hook;
271 __free_hook = save_free_hook;
272 for(ar_ptr = &main_arena;;) {
273 (void)mutex_unlock(&ar_ptr->mutex);
274 ar_ptr = ar_ptr->next;
275 if(ar_ptr == &main_arena) break;
277 (void)mutex_unlock(&list_lock);
282 /* In NPTL, unlocking a mutex in the child process after a
283 fork() is currently unsafe, whereas re-initializing it is safe and
284 does not leak resources. Therefore, a special atfork handler is
285 installed for the child. */
288 ptmalloc_unlock_all2 (void)
292 if(__malloc_initialized < 1)
294 tsd_setspecific(arena_key, save_arena);
295 __malloc_hook = save_malloc_hook;
296 __free_hook = save_free_hook;
300 for(ar_ptr = &main_arena;;) {
301 mutex_init(&ar_ptr->mutex);
303 if (ar_ptr != save_arena) {
304 ar_ptr->next_free = free_list;
308 ar_ptr = ar_ptr->next;
309 if(ar_ptr == &main_arena) break;
311 mutex_init(&list_lock);
312 atfork_recursive_cntr = 0;
317 #define ptmalloc_unlock_all2 ptmalloc_unlock_all
321 /* Initialization routine. */
323 extern char **_environ;
327 next_env_entry (char ***position)
329 char **current = *position;
332 while (*current != NULL)
334 if (__builtin_expect ((*current)[0] == 'M', 0)
335 && (*current)[1] == 'A'
336 && (*current)[2] == 'L'
337 && (*current)[3] == 'L'
338 && (*current)[4] == 'O'
339 && (*current)[5] == 'C'
340 && (*current)[6] == '_')
342 result = &(*current)[7];
344 /* Save current position for next visit. */
345 *position = ++current;
359 __failing_morecore (ptrdiff_t d)
361 return (void *) MORECORE_FAILURE;
364 extern struct dl_open_hook *_dl_open_hook;
365 libc_hidden_proto (_dl_open_hook);
371 if(__malloc_initialized >= 0) return;
372 __malloc_initialized = 0;
375 /* In case this libc copy is in a non-default namespace, never use brk.
376 Likewise if dlopened from statically linked program. */
380 if (_dl_open_hook != NULL
381 || (_dl_addr (ptmalloc_init, &di, &l, NULL) != 0
382 && l->l_ns != LM_ID_BASE))
383 __morecore = __failing_morecore;
386 tsd_key_create(&arena_key, NULL);
387 tsd_setspecific(arena_key, (void *)&main_arena);
388 thread_atfork(ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_unlock_all2);
389 const char *s = NULL;
390 if (__builtin_expect (_environ != NULL, 1))
392 char **runp = _environ;
395 while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL,
398 size_t len = strcspn (envline, "=");
400 if (envline[len] != '=')
401 /* This is a "MALLOC_" variable at the end of the string
402 without a '=' character. Ignore it since otherwise we
403 will access invalid memory below. */
409 if (memcmp (envline, "CHECK_", 6) == 0)
413 if (! __builtin_expect (__libc_enable_secure, 0))
415 if (memcmp (envline, "TOP_PAD_", 8) == 0)
416 mALLOPt(M_TOP_PAD, atoi(&envline[9]));
417 else if (memcmp (envline, "PERTURB_", 8) == 0)
418 mALLOPt(M_PERTURB, atoi(&envline[9]));
422 if (! __builtin_expect (__libc_enable_secure, 0))
424 if (memcmp (envline, "MMAP_MAX_", 9) == 0)
425 mALLOPt(M_MMAP_MAX, atoi(&envline[10]));
427 else if (memcmp (envline, "ARENA_MAX", 9) == 0)
428 mALLOPt(M_ARENA_MAX, atoi(&envline[10]));
434 if (! __builtin_expect (__libc_enable_secure, 0))
436 if (memcmp (envline, "ARENA_TEST", 10) == 0)
437 mALLOPt(M_ARENA_TEST, atoi(&envline[11]));
442 if (! __builtin_expect (__libc_enable_secure, 0))
444 if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0)
445 mALLOPt(M_TRIM_THRESHOLD, atoi(&envline[16]));
446 else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0)
447 mALLOPt(M_MMAP_THRESHOLD, atoi(&envline[16]));
456 mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
457 if (check_action != 0)
458 __malloc_check_init();
460 void (*hook) (void) = force_reg (__malloc_initialize_hook);
463 __malloc_initialized = 1;
466 /* There are platforms (e.g. Hurd) with a link-time hook mechanism. */
467 #ifdef thread_atfork_static
468 thread_atfork_static(ptmalloc_lock_all, ptmalloc_unlock_all, \
469 ptmalloc_unlock_all2)
474 /* Managing heaps and arenas (for concurrent threads) */
478 /* Print the complete contents of a single heap to stderr. */
481 dump_heap(heap_info *heap)
486 fprintf(stderr, "Heap %p, size %10lx:\n", heap, (long)heap->size);
487 ptr = (heap->ar_ptr != (mstate)(heap+1)) ?
488 (char*)(heap + 1) : (char*)(heap + 1) + sizeof(struct malloc_state);
489 p = (mchunkptr)(((unsigned long)ptr + MALLOC_ALIGN_MASK) &
492 fprintf(stderr, "chunk %p size %10lx", p, (long)p->size);
493 if(p == top(heap->ar_ptr)) {
494 fprintf(stderr, " (top)\n");
496 } else if(p->size == (0|PREV_INUSE)) {
497 fprintf(stderr, " (fence)\n");
500 fprintf(stderr, "\n");
505 #endif /* MALLOC_DEBUG > 1 */
507 /* If consecutive mmap (0, HEAP_MAX_SIZE << 1, ...) calls return decreasing
508 addresses as opposed to increasing, new_heap would badly fragment the
509 address space. In that case remember the second HEAP_MAX_SIZE part
510 aligned to HEAP_MAX_SIZE from last mmap (0, HEAP_MAX_SIZE << 1, ...)
511 call (if it is already aligned) and try to reuse it next time. We need
512 no locking for it, as kernel ensures the atomicity for us - worst case
513 we'll call mmap (addr, HEAP_MAX_SIZE, ...) for some value of addr in
514 multiple threads, but only one will succeed. */
515 static char *aligned_heap_area;
517 /* Create a new heap. size is automatically rounded up to a multiple
522 new_heap(size_t size, size_t top_pad)
524 size_t page_mask = GLRO(dl_pagesize) - 1;
529 if(size+top_pad < HEAP_MIN_SIZE)
530 size = HEAP_MIN_SIZE;
531 else if(size+top_pad <= HEAP_MAX_SIZE)
533 else if(size > HEAP_MAX_SIZE)
536 size = HEAP_MAX_SIZE;
537 size = (size + page_mask) & ~page_mask;
539 /* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed.
540 No swap space needs to be reserved for the following large
541 mapping (on Linux, this is the case for all non-writable mappings
544 if(aligned_heap_area) {
545 p2 = (char *)MMAP(aligned_heap_area, HEAP_MAX_SIZE, PROT_NONE,
546 MAP_PRIVATE|MAP_NORESERVE);
547 aligned_heap_area = NULL;
548 if (p2 != MAP_FAILED && ((unsigned long)p2 & (HEAP_MAX_SIZE-1))) {
549 munmap(p2, HEAP_MAX_SIZE);
553 if(p2 == MAP_FAILED) {
554 p1 = (char *)MMAP(0, HEAP_MAX_SIZE<<1, PROT_NONE,
555 MAP_PRIVATE|MAP_NORESERVE);
556 if(p1 != MAP_FAILED) {
557 p2 = (char *)(((unsigned long)p1 + (HEAP_MAX_SIZE-1))
558 & ~(HEAP_MAX_SIZE-1));
563 aligned_heap_area = p2 + HEAP_MAX_SIZE;
564 munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul);
566 /* Try to take the chance that an allocation of only HEAP_MAX_SIZE
567 is already aligned. */
568 p2 = (char *)MMAP(0, HEAP_MAX_SIZE, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
571 if((unsigned long)p2 & (HEAP_MAX_SIZE-1)) {
572 munmap(p2, HEAP_MAX_SIZE);
577 if(mprotect(p2, size, PROT_READ|PROT_WRITE) != 0) {
578 munmap(p2, HEAP_MAX_SIZE);
583 h->mprotect_size = size;
584 THREAD_STAT(stat_n_heaps++);
588 /* Grow a heap. size is automatically rounded up to a
589 multiple of the page size. */
592 grow_heap(heap_info *h, long diff)
594 size_t page_mask = GLRO(dl_pagesize) - 1;
597 diff = (diff + page_mask) & ~page_mask;
598 new_size = (long)h->size + diff;
599 if((unsigned long) new_size > (unsigned long) HEAP_MAX_SIZE)
601 if((unsigned long) new_size > h->mprotect_size) {
602 if (mprotect((char *)h + h->mprotect_size,
603 (unsigned long) new_size - h->mprotect_size,
604 PROT_READ|PROT_WRITE) != 0)
606 h->mprotect_size = new_size;
616 shrink_heap(heap_info *h, long diff)
620 new_size = (long)h->size - diff;
621 if(new_size < (long)sizeof(*h))
623 /* Try to re-map the extra heap space freshly to save memory, and
624 make it inaccessible. */
625 if (__builtin_expect (__libc_enable_secure, 0))
627 if((char *)MMAP((char *)h + new_size, diff, PROT_NONE,
628 MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
630 h->mprotect_size = new_size;
633 madvise ((char *)h + new_size, diff, MADV_DONTNEED);
634 /*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/
642 #define delete_heap(heap) \
644 if ((char *)(heap) + HEAP_MAX_SIZE == aligned_heap_area) \
645 aligned_heap_area = NULL; \
646 munmap((char*)(heap), HEAP_MAX_SIZE); \
651 heap_trim(heap_info *heap, size_t pad)
653 mstate ar_ptr = heap->ar_ptr;
654 unsigned long pagesz = GLRO(dl_pagesize);
655 mchunkptr top_chunk = top(ar_ptr), p, bck, fwd;
656 heap_info *prev_heap;
657 long new_size, top_size, extra;
659 /* Can this heap go away completely? */
660 while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) {
661 prev_heap = heap->prev;
662 p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ));
663 assert(p->size == (0|PREV_INUSE)); /* must be fencepost */
665 new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ);
666 assert(new_size>0 && new_size<(long)(2*MINSIZE));
668 new_size += p->prev_size;
669 assert(new_size>0 && new_size<HEAP_MAX_SIZE);
670 if(new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz)
672 ar_ptr->system_mem -= heap->size;
673 arena_mem -= heap->size;
676 if(!prev_inuse(p)) { /* consolidate backward */
680 assert(((unsigned long)((char*)p + new_size) & (pagesz-1)) == 0);
681 assert( ((char*)p + new_size) == ((char*)heap + heap->size) );
682 top(ar_ptr) = top_chunk = p;
683 set_head(top_chunk, new_size | PREV_INUSE);
684 /*check_chunk(ar_ptr, top_chunk);*/
686 top_size = chunksize(top_chunk);
687 extra = (top_size - pad - MINSIZE - 1) & ~(pagesz - 1);
688 if(extra < (long)pagesz)
691 if(shrink_heap(heap, extra) != 0)
693 ar_ptr->system_mem -= extra;
696 /* Success. Adjust top accordingly. */
697 set_head(top_chunk, (top_size - extra) | PREV_INUSE);
698 /*check_chunk(ar_ptr, top_chunk);*/
702 /* Create a new arena with initial size "size". */
705 _int_new_arena(size_t size)
710 unsigned long misalign;
712 h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT),
715 /* Maybe size is too large to fit in a single heap. So, just try
716 to create a minimally-sized arena and let _int_malloc() attempt
717 to deal with the large request via mmap_chunk(). */
718 h = new_heap(sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT, mp_.top_pad);
722 a = h->ar_ptr = (mstate)(h+1);
723 malloc_init_state(a);
725 a->system_mem = a->max_system_mem = h->size;
726 arena_mem += h->size;
728 /* Set up the top chunk, with proper alignment. */
729 ptr = (char *)(a + 1);
730 misalign = (unsigned long)chunk2mem(ptr) & MALLOC_ALIGN_MASK;
732 ptr += MALLOC_ALIGNMENT - misalign;
733 top(a) = (mchunkptr)ptr;
734 set_head(top(a), (((char*)h + h->size) - ptr) | PREV_INUSE);
736 tsd_setspecific(arena_key, (void *)a);
737 mutex_init(&a->mutex);
738 (void)mutex_lock(&a->mutex);
741 (void)mutex_lock(&list_lock);
744 /* Add the new arena to the global list. */
745 a->next = main_arena.next;
746 atomic_write_barrier ();
750 (void)mutex_unlock(&list_lock);
753 THREAD_STAT(++(a->stat_lock_loop));
763 mstate result = free_list;
766 (void)mutex_lock(&list_lock);
769 free_list = result->next_free;
770 (void)mutex_unlock(&list_lock);
774 (void)mutex_lock(&result->mutex);
775 tsd_setspecific(arena_key, (void *)result);
776 THREAD_STAT(++(result->stat_lock_loop));
788 static mstate next_to_use;
789 if (next_to_use == NULL)
790 next_to_use = &main_arena;
792 result = next_to_use;
795 if (!mutex_trylock(&result->mutex))
798 result = result->next;
800 while (result != next_to_use);
802 /* No arena available. Wait for the next in line. */
803 (void)mutex_lock(&result->mutex);
806 tsd_setspecific(arena_key, (void *)result);
807 THREAD_STAT(++(result->stat_lock_loop));
808 next_to_use = result->next;
816 arena_get2(mstate a_tsd, size_t size)
821 static size_t narenas_limit;
823 a = get_free_list ();
826 /* Nothing immediately available, so generate a new arena. */
827 if (narenas_limit == 0)
829 if (mp_.arena_max != 0)
830 narenas_limit = mp_.arena_max;
833 int n = __get_nprocs ();
836 narenas_limit = NARENAS_FROM_NCORES (n);
838 /* We have no information about the system. Assume two
840 narenas_limit = NARENAS_FROM_NCORES (2);
845 if (__builtin_expect (n <= mp_.arena_test || n < narenas_limit, 0))
847 if (catomic_compare_and_exchange_bool_acq (&narenas, n + 1, n))
849 a = _int_new_arena (size);
850 if (__builtin_expect (a == NULL, 0))
851 catomic_decrement (&narenas);
858 a = a_tsd = &main_arena;
862 /* This can only happen while initializing the new arena. */
863 (void)mutex_lock(&main_arena.mutex);
864 THREAD_STAT(++(main_arena.stat_lock_wait));
869 /* Check the global, circularly linked list for available arenas. */
870 bool retried = false;
873 if(!mutex_trylock(&a->mutex)) {
875 (void)mutex_unlock(&list_lock);
876 THREAD_STAT(++(a->stat_lock_loop));
877 tsd_setspecific(arena_key, (void *)a);
883 /* If not even the list_lock can be obtained, try again. This can
884 happen during `atfork', or for example on systems where thread
885 creation makes it temporarily impossible to obtain _any_
887 if(!retried && mutex_trylock(&list_lock)) {
888 /* We will block to not run in a busy loop. */
889 (void)mutex_lock(&list_lock);
891 /* Since we blocked there might be an arena available now. */
897 /* Nothing immediately available, so generate a new arena. */
898 a = _int_new_arena(size);
899 (void)mutex_unlock(&list_lock);
906 static void __attribute__ ((section ("__libc_thread_freeres_fn")))
907 arena_thread_freeres (void)
910 mstate a = tsd_getspecific(arena_key, vptr);
911 tsd_setspecific(arena_key, NULL);
915 (void)mutex_lock(&list_lock);
916 a->next_free = free_list;
918 (void)mutex_unlock(&list_lock);
921 text_set_element (__libc_thread_subfreeres, arena_thread_freeres);