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Improve malloc initialization sequence

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The current malloc initialization is quite convoluted. Instead of
sometimes calling malloc_consolidate from ptmalloc_init, call
malloc_init_state early so that the main_arena is always initialized.
The special initialization can now be removed from malloc_consolidate.
This also fixes BZ #22159.

Check all calls to malloc_consolidate and remove calls that are
redundant initialization after ptmalloc_init, like in int_mallinfo
and __libc_mallopt (but keep the latter as consolidation is required for
set_max_fast).  Update comments to improve clarity.

Remove impossible initialization check from _int_malloc, fix assert
in do_check_malloc_state to ensure arena->top != 0.  Fix the obvious bugs
in do_check_free_chunk and do_check_remalloced_chunk to enable single
threaded malloc debugging (do_check_malloc_state is not thread safe!).

	[BZ #22159]
	* malloc/arena.c (ptmalloc_init): Call malloc_init_state.
	* malloc/malloc.c (do_check_free_chunk): Fix build bug.
	(do_check_remalloced_chunk): Fix build bug.
	(do_check_malloc_state): Add assert that checks arena->top.
	(malloc_consolidate): Remove initialization.
	(int_mallinfo): Remove call to malloc_consolidate.
	(__libc_mallopt): Clarify why malloc_consolidate is needed.
This commit is contained in:
Wilco Dijkstra
2017-10-17 18:55:16 +01:00
parent e956075a5a
commit 3381be5cde
3 changed files with 102 additions and 117 deletions
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13
malloc/arena.c
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@ -307,13 +307,9 @@ ptmalloc_init (void)
thread_arena = &main_arena;
#if HAVE_TUNABLES
/* Ensure initialization/consolidation and do it under a lock so that a
thread attempting to use the arena in parallel waits on us till we
finish. */
__libc_lock_lock (main_arena.mutex);
malloc_consolidate (&main_arena);
malloc_init_state (&main_arena);
#if HAVE_TUNABLES
TUNABLE_GET (check, int32_t, TUNABLE_CALLBACK (set_mallopt_check));
TUNABLE_GET (top_pad, size_t, TUNABLE_CALLBACK (set_top_pad));
TUNABLE_GET (perturb, int32_t, TUNABLE_CALLBACK (set_perturb_byte));
@ -322,13 +318,12 @@ ptmalloc_init (void)
TUNABLE_GET (mmap_max, int32_t, TUNABLE_CALLBACK (set_mmaps_max));
TUNABLE_GET (arena_max, size_t, TUNABLE_CALLBACK (set_arena_max));
TUNABLE_GET (arena_test, size_t, TUNABLE_CALLBACK (set_arena_test));
#if USE_TCACHE
# if USE_TCACHE
TUNABLE_GET (tcache_max, size_t, TUNABLE_CALLBACK (set_tcache_max));
TUNABLE_GET (tcache_count, size_t, TUNABLE_CALLBACK (set_tcache_count));
TUNABLE_GET (tcache_unsorted_limit, size_t,
TUNABLE_CALLBACK (set_tcache_unsorted_limit));
#endif
__libc_lock_unlock (main_arena.mutex);
# endif
#else
const char *s = NULL;
if (__glibc_likely (_environ != NULL))