diff options
Diffstat (limited to 'malloc/arena.c')
| -rw-r--r-- | malloc/arena.c | 58 |
1 files changed, 17 insertions, 41 deletions
diff --git a/malloc/arena.c b/malloc/arena.c index cd26cdd..bba83e9 100644 --- a/malloc/arena.c +++ b/malloc/arena.c @@ -133,10 +133,6 @@ static void *(*save_malloc_hook)(size_t __size, const void *); static void (*save_free_hook) (void *__ptr, const void *); static void *save_arena; -# ifdef ATFORK_MEM -ATFORK_MEM; -# endif - /* Magic value for the thread-specific arena pointer when malloc_atfork() is in use. */ @@ -202,14 +198,14 @@ free_atfork (void *mem, const void *caller) /* Counter for number of times the list is locked by the same thread. */ static unsigned int atfork_recursive_cntr; -/* The following two functions are registered via thread_atfork() to - make sure that the mutexes remain in a consistent state in the - fork()ed version of a thread. Also adapt the malloc and free hooks - temporarily, because the `atfork' handler mechanism may use - malloc/free internally (e.g. in LinuxThreads). */ +/* The following three functions are called around fork from a + multi-threaded process. We do not use the general fork handler + mechanism to make sure that our handlers are the last ones being + called, so that other fork handlers can use the malloc + subsystem. */ -static void -ptmalloc_lock_all (void) +void +__malloc_fork_lock_parent (void) { mstate ar_ptr; @@ -217,7 +213,7 @@ ptmalloc_lock_all (void) return; /* We do not acquire free_list_lock here because we completely - reconstruct free_list in ptmalloc_unlock_all2. */ + reconstruct free_list in __malloc_fork_unlock_child. */ if (mutex_trylock (&list_lock)) { @@ -242,7 +238,7 @@ ptmalloc_lock_all (void) __free_hook = free_atfork; /* Only the current thread may perform malloc/free calls now. save_arena will be reattached to the current thread, in - ptmalloc_lock_all, so save_arena->attached_threads is not + __malloc_fork_lock_parent, so save_arena->attached_threads is not updated. */ save_arena = thread_arena; thread_arena = ATFORK_ARENA_PTR; @@ -250,8 +246,8 @@ out: ++atfork_recursive_cntr; } -static void -ptmalloc_unlock_all (void) +void +__malloc_fork_unlock_parent (void) { mstate ar_ptr; @@ -262,8 +258,8 @@ ptmalloc_unlock_all (void) return; /* Replace ATFORK_ARENA_PTR with save_arena. - save_arena->attached_threads was not changed in ptmalloc_lock_all - and is still correct. */ + save_arena->attached_threads was not changed in + __malloc_fork_lock_parent and is still correct. */ thread_arena = save_arena; __malloc_hook = save_malloc_hook; __free_hook = save_free_hook; @@ -277,15 +273,8 @@ ptmalloc_unlock_all (void) (void) mutex_unlock (&list_lock); } -# ifdef __linux__ - -/* In NPTL, unlocking a mutex in the child process after a - fork() is currently unsafe, whereas re-initializing it is safe and - does not leak resources. Therefore, a special atfork handler is - installed for the child. */ - -static void -ptmalloc_unlock_all2 (void) +void +__malloc_fork_unlock_child (void) { mstate ar_ptr; @@ -321,11 +310,6 @@ ptmalloc_unlock_all2 (void) atfork_recursive_cntr = 0; } -# else - -# define ptmalloc_unlock_all2 ptmalloc_unlock_all -# endif - /* Initialization routine. */ #include <string.h> extern char **_environ; @@ -394,7 +378,6 @@ ptmalloc_init (void) #endif thread_arena = &main_arena; - thread_atfork (ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_unlock_all2); const char *s = NULL; if (__glibc_likely (_environ != NULL)) { @@ -469,14 +452,6 @@ ptmalloc_init (void) __malloc_initialized = 1; } -/* There are platforms (e.g. Hurd) with a link-time hook mechanism. */ -#ifdef thread_atfork_static -thread_atfork_static (ptmalloc_lock_all, ptmalloc_unlock_all, \ - ptmalloc_unlock_all2) -#endif - - - /* Managing heaps and arenas (for concurrent threads) */ #if MALLOC_DEBUG > 1 @@ -822,7 +797,8 @@ _int_new_arena (size_t size) limit is reached). At this point, some arena has to be attached to two threads. We could acquire the arena lock before list_lock to make it less likely that reused_arena picks this new arena, - but this could result in a deadlock with ptmalloc_lock_all. */ + but this could result in a deadlock with + __malloc_fork_lock_parent. */ (void) mutex_lock (&a->mutex); |