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Linux: Move __reclaim_stacks into the fork implementation in libc
As a result, __libc_pthread_init is no longer needed. Tested-by: Carlos O'Donell <carlos@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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@ -308,7 +308,6 @@ libc {
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__libc_cleanup_push_defer;
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__libc_dl_error_tsd;
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__libc_multiple_threads;
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__libc_pthread_init;
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__lll_clocklock_elision;
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__lll_lock_elision;
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__lll_lock_wait;
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@ -754,111 +754,3 @@ __deallocate_stack (struct pthread *pd)
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lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
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}
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/* In case of a fork() call the memory allocation in the child will be
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the same but only one thread is running. All stacks except that of
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the one running thread are not used anymore. We have to recycle
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them. */
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void
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__reclaim_stacks (void)
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{
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struct pthread *self = (struct pthread *) THREAD_SELF;
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/* No locking necessary. The caller is the only stack in use. But
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we have to be aware that we might have interrupted a list
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operation. */
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if (GL (dl_in_flight_stack) != 0)
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{
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bool add_p = GL (dl_in_flight_stack) & 1;
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list_t *elem = (list_t *) (GL (dl_in_flight_stack) & ~(uintptr_t) 1);
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if (add_p)
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{
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/* We always add at the beginning of the list. So in this case we
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only need to check the beginning of these lists to see if the
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pointers at the head of the list are inconsistent. */
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list_t *l = NULL;
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if (GL (dl_stack_used).next->prev != &GL (dl_stack_used))
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l = &GL (dl_stack_used);
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else if (GL (dl_stack_cache).next->prev != &GL (dl_stack_cache))
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l = &GL (dl_stack_cache);
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if (l != NULL)
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{
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assert (l->next->prev == elem);
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elem->next = l->next;
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elem->prev = l;
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l->next = elem;
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}
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}
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else
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{
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/* We can simply always replay the delete operation. */
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elem->next->prev = elem->prev;
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elem->prev->next = elem->next;
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}
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GL (dl_in_flight_stack) = 0;
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}
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/* Mark all stacks except the still running one as free. */
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list_t *runp;
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list_for_each (runp, &GL (dl_stack_used))
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{
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struct pthread *curp = list_entry (runp, struct pthread, list);
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if (curp != self)
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{
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/* This marks the stack as free. */
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curp->tid = 0;
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/* Account for the size of the stack. */
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GL (dl_stack_cache_actsize) += curp->stackblock_size;
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if (curp->specific_used)
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{
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/* Clear the thread-specific data. */
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memset (curp->specific_1stblock, '\0',
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sizeof (curp->specific_1stblock));
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curp->specific_used = false;
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for (size_t cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
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if (curp->specific[cnt] != NULL)
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{
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memset (curp->specific[cnt], '\0',
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sizeof (curp->specific_1stblock));
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/* We have allocated the block which we do not
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free here so re-set the bit. */
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curp->specific_used = true;
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}
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}
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}
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}
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/* Add the stack of all running threads to the cache. */
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list_splice (&GL (dl_stack_used), &GL (dl_stack_cache));
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/* Remove the entry for the current thread to from the cache list
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and add it to the list of running threads. Which of the two
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lists is decided by the user_stack flag. */
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list_del (&self->list);
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/* Re-initialize the lists for all the threads. */
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INIT_LIST_HEAD (&GL (dl_stack_used));
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INIT_LIST_HEAD (&GL (dl_stack_user));
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if (__glibc_unlikely (THREAD_GETMEM (self, user_stack)))
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list_add (&self->list, &GL (dl_stack_user));
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else
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list_add (&self->list, &GL (dl_stack_used));
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/* There is one thread running. */
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__nptl_nthreads = 1;
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/* Initialize locks. */
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GL (dl_stack_cache_lock) = LLL_LOCK_INITIALIZER;
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__default_pthread_attr_lock = LLL_LOCK_INITIALIZER;
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}
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@ -172,9 +172,6 @@ __pthread_initialize_minimal_internal (void)
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__default_pthread_attr.internal.stacksize = limit.rlim_cur;
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__default_pthread_attr.internal.guardsize = GLRO (dl_pagesize);
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lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
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/* Register the fork generation counter with the libc. */
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__libc_pthread_init (__reclaim_stacks);
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}
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strong_alias (__pthread_initialize_minimal_internal,
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__pthread_initialize_minimal)
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@ -333,10 +333,6 @@ extern void __free_tcb (struct pthread *pd) attribute_hidden;
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/* Free allocated stack. */
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extern void __deallocate_stack (struct pthread *pd) attribute_hidden;
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/* Mark all the stacks except for the current one as available. This
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function also re-initializes the lock for the stack cache. */
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extern void __reclaim_stacks (void) attribute_hidden;
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/* Change the permissions of a thread stack. Called from
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_dl_make_stacks_executable and pthread_create. */
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int
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@ -372,9 +368,6 @@ extern unsigned long int __fork_generation attribute_hidden;
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/* Pointer to the fork generation counter in the thread library. */
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extern unsigned long int *__fork_generation_pointer attribute_hidden;
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/* Register the generation counter in the libpthread with the libc. */
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extern void __libc_pthread_init (void (*reclaim) (void));
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extern size_t __pthread_get_minstack (const pthread_attr_t *attr);
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/* Namespace save aliases. */
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@ -35,6 +35,7 @@
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#include <nss/nss_database.h>
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#include <unwind-link.h>
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#include <sys/single_threaded.h>
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#include <list.h>
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static void
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fresetlockfiles (void)
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@ -46,6 +47,106 @@ fresetlockfiles (void)
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_IO_lock_init (*((_IO_lock_t *) _IO_iter_file(i)->_lock));
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}
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/* In case of a fork() call the memory allocation in the child will be
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the same but only one thread is running. All stacks except that of
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the one running thread are not used anymore. We have to recycle
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them. */
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static void
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reclaim_stacks (void)
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{
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struct pthread *self = (struct pthread *) THREAD_SELF;
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/* No locking necessary. The caller is the only stack in use. But
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we have to be aware that we might have interrupted a list
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operation. */
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if (GL (dl_in_flight_stack) != 0)
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{
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bool add_p = GL (dl_in_flight_stack) & 1;
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list_t *elem = (list_t *) (GL (dl_in_flight_stack) & ~(uintptr_t) 1);
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if (add_p)
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{
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/* We always add at the beginning of the list. So in this case we
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only need to check the beginning of these lists to see if the
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pointers at the head of the list are inconsistent. */
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list_t *l = NULL;
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if (GL (dl_stack_used).next->prev != &GL (dl_stack_used))
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l = &GL (dl_stack_used);
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else if (GL (dl_stack_cache).next->prev != &GL (dl_stack_cache))
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l = &GL (dl_stack_cache);
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if (l != NULL)
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{
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assert (l->next->prev == elem);
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elem->next = l->next;
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elem->prev = l;
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l->next = elem;
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}
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}
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else
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{
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/* We can simply always replay the delete operation. */
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elem->next->prev = elem->prev;
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elem->prev->next = elem->next;
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}
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GL (dl_in_flight_stack) = 0;
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}
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/* Mark all stacks except the still running one as free. */
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list_t *runp;
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list_for_each (runp, &GL (dl_stack_used))
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{
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struct pthread *curp = list_entry (runp, struct pthread, list);
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if (curp != self)
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{
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/* This marks the stack as free. */
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curp->tid = 0;
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/* Account for the size of the stack. */
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GL (dl_stack_cache_actsize) += curp->stackblock_size;
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if (curp->specific_used)
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{
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/* Clear the thread-specific data. */
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memset (curp->specific_1stblock, '\0',
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sizeof (curp->specific_1stblock));
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curp->specific_used = false;
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for (size_t cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
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if (curp->specific[cnt] != NULL)
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{
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memset (curp->specific[cnt], '\0',
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sizeof (curp->specific_1stblock));
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/* We have allocated the block which we do not
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free here so re-set the bit. */
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curp->specific_used = true;
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}
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}
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}
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}
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/* Add the stack of all running threads to the cache. */
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list_splice (&GL (dl_stack_used), &GL (dl_stack_cache));
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/* Remove the entry for the current thread to from the cache list
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and add it to the list of running threads. Which of the two
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lists is decided by the user_stack flag. */
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list_del (&self->list);
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/* Re-initialize the lists for all the threads. */
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INIT_LIST_HEAD (&GL (dl_stack_used));
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INIT_LIST_HEAD (&GL (dl_stack_user));
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if (__glibc_unlikely (THREAD_GETMEM (self, user_stack)))
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list_add (&self->list, &GL (dl_stack_user));
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else
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list_add (&self->list, &GL (dl_stack_used));
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}
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pid_t
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__libc_fork (void)
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@ -112,6 +213,13 @@ __libc_fork (void)
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{
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__libc_unwind_link_after_fork ();
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/* There is one thread running. */
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__nptl_nthreads = 1;
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/* Initialize thread library locks. */
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GL (dl_stack_cache_lock) = LLL_LOCK_INITIALIZER;
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__default_pthread_attr_lock = LLL_LOCK_INITIALIZER;
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/* Release malloc locks. */
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call_function_static_weak (__malloc_fork_unlock_child);
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@ -128,6 +236,8 @@ __libc_fork (void)
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/* Reset the lock the dynamic loader uses to protect its data. */
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__rtld_lock_initialize (GL(dl_load_lock));
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reclaim_stacks ();
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/* Run the handlers registered for the child. */
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__run_fork_handlers (atfork_run_child, multiple_threads);
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}
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