[v2] malloc: Clean up __malloc_initialized
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| dj/TryBot-apply_patch |
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Patch applied to master at the time it was sent
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Commit Message
It can be assumed that ptmalloc_init is always called in a
single-threaded context because pthread_create calls malloc before
spawning a thread. As a result, a boolean value for
__malloc_initialized is sufficient to ensure that the function body is
executed only once.
Further, __malloc_initialized is mentioned in Versions when it is
actually an internal symbol. Drop that reference and the macro
definition to __libc_malloc_initialized since it does not have an
external use.
---
Changes from v1:
- Retained attribute_hidden extern declaration.
include/malloc.h | 6 ++----
malloc/Versions | 2 +-
malloc/arena.c | 16 +++++++++-------
malloc/malloc.c | 14 +++++++-------
malloc/mcheck.c | 2 +-
5 files changed, 20 insertions(+), 20 deletions(-)
Comments
On 6/18/21 3:23 PM, Siddhesh Poyarekar via Libc-alpha wrote:
> It can be assumed that ptmalloc_init is always called in a
> single-threaded context because pthread_create calls malloc before
> spawning a thread. As a result, a boolean value for
> __malloc_initialized is sufficient to ensure that the function body is
> executed only once.
>
> Further, __malloc_initialized is mentioned in Versions when it is
> actually an internal symbol. Drop that reference and the macro
> definition to __libc_malloc_initialized since it does not have an
> external use.
> ---
> Changes from v1:
> - Retained attribute_hidden extern declaration.
Florian what do you think? I've made the change you requested.
Siddhesh
On 6/18/21 3:23 PM, Siddhesh Poyarekar via Libc-alpha wrote:
> It can be assumed that ptmalloc_init is always called in a
> single-threaded context because pthread_create calls malloc before
> spawning a thread. As a result, a boolean value for
> __malloc_initialized is sufficient to ensure that the function body is
> executed only once.
>
> Further, __malloc_initialized is mentioned in Versions when it is
> actually an internal symbol. Drop that reference and the macro
> definition to __libc_malloc_initialized since it does not have an
> external use.
Ahh no, this breaks mcheck initialization, which depends on the
intermediate value to ensure it is initialized only once. I'll figure
out a way to work this into the hooks removal patchset since it
simplifies the mcheck functionality a bit.
Siddhesh
@@ -4,12 +4,10 @@
# ifndef _ISOMAC
# include <rtld-malloc.h>
+# include <stdbool.h>
-/* In the GNU libc we rename the global variable
- `__malloc_initialized' to `__libc_malloc_initialized'. */
-#define __malloc_initialized __libc_malloc_initialized
/* Nonzero if the malloc is already initialized. */
-extern int __malloc_initialized attribute_hidden;
+extern bool __malloc_initialized attribute_hidden;
struct malloc_state;
typedef struct malloc_state *mstate;
@@ -9,7 +9,7 @@ libc {
__libc_valloc;
__malloc_initialize_hook; __free_hook; __malloc_hook; __realloc_hook;
__memalign_hook; __after_morecore_hook;
- __malloc_initialized; __default_morecore; __morecore;
+ __default_morecore; __morecore;
# functions used in inline functions or macros
_obstack_allocated_p; _obstack_begin; _obstack_begin_1;
@@ -97,7 +97,7 @@ static mstate free_list;
__libc_lock_define_initialized (static, list_lock);
/* Already initialized? */
-int __malloc_initialized = -1;
+bool __malloc_initialized;
/**************************************************************************/
@@ -143,7 +143,7 @@ int __malloc_initialized = -1;
void
__malloc_fork_lock_parent (void)
{
- if (__malloc_initialized < 1)
+ if (!__malloc_initialized)
return;
/* We do not acquire free_list_lock here because we completely
@@ -163,7 +163,7 @@ __malloc_fork_lock_parent (void)
void
__malloc_fork_unlock_parent (void)
{
- if (__malloc_initialized < 1)
+ if (!__malloc_initialized)
return;
for (mstate ar_ptr = &main_arena;; )
@@ -179,7 +179,7 @@ __malloc_fork_unlock_parent (void)
void
__malloc_fork_unlock_child (void)
{
- if (__malloc_initialized < 1)
+ if (!__malloc_initialized)
return;
/* Push all arenas to the free list, except thread_arena, which is
@@ -287,13 +287,16 @@ extern struct dl_open_hook *_dl_open_hook;
libc_hidden_proto (_dl_open_hook);
#endif
+/* Malloc initialization. We assume that the function is always called in a
+ single threaded context because pthread_create calls malloc before spawning
+ a thread. */
static void
ptmalloc_init (void)
{
- if (__malloc_initialized >= 0)
+ if (__malloc_initialized)
return;
- __malloc_initialized = 0;
+ __malloc_initialized = true;
#ifdef USE_MTAG
if ((TUNABLE_GET_FULL (glibc, mem, tagging, int32_t, NULL) & 1) != 0)
@@ -410,7 +413,6 @@ ptmalloc_init (void)
if (hook != NULL)
(*hook)();
#endif
- __malloc_initialized = 1;
}
/* Managing heaps and arenas (for concurrent threads) */
@@ -3562,7 +3562,7 @@ libc_hidden_def (__libc_memalign)
void *
__libc_valloc (size_t bytes)
{
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
void *address = RETURN_ADDRESS (0);
@@ -3573,7 +3573,7 @@ __libc_valloc (size_t bytes)
void *
__libc_pvalloc (size_t bytes)
{
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
void *address = RETURN_ADDRESS (0);
@@ -5077,7 +5077,7 @@ __malloc_trim (size_t s)
{
int result = 0;
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
mstate ar_ptr = &main_arena;
@@ -5212,7 +5212,7 @@ __libc_mallinfo2 (void)
struct mallinfo2 m;
mstate ar_ptr;
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
memset (&m, 0, sizeof (m));
@@ -5263,7 +5263,7 @@ __malloc_stats (void)
mstate ar_ptr;
unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
_IO_flockfile (stderr);
int old_flags2 = stderr->_flags2;
@@ -5432,7 +5432,7 @@ __libc_mallopt (int param_number, int value)
mstate av = &main_arena;
int res = 1;
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
__libc_lock_lock (av->mutex);
@@ -5691,7 +5691,7 @@ __malloc_info (int options, FILE *fp)
- if (__malloc_initialized < 0)
+ if (!__malloc_initialized)
ptmalloc_init ();
fputs ("<malloc version=\"1\">\n", fp);
@@ -375,7 +375,7 @@ mcheck (void (*func) (enum mcheck_status))
abortfunc = (func != NULL) ? func : &mabort;
/* These hooks may not be safely inserted if malloc is already in use. */
- if (__malloc_initialized <= 0 && !mcheck_used)
+ if (!__malloc_initialized && !mcheck_used)
{
/* We call malloc() once here to ensure it is initialized. */
void *p = malloc (0);