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Add init_lock, and use it to protect against allocator initialization

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races.  This isn't currently necessary for libpthread or libthr, but
without it external threads libraries like the linuxthreads port are
not safe to use.

Reported by:	ganbold@micom.mng.net
This commit is contained in:
Jason Evans 2006-04-04 19:46:28 +00:00
parent 522bc71e0a
commit cf01f0d7c5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=157498
1 changed files with 21 additions and 8 deletions
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29
lib/libc/stdlib/malloc.c
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@ -350,8 +350,12 @@ typedef struct {
spinlock_t lock;
} malloc_mutex_t;
/* Set to true once the allocator has been initialized. */
static bool malloc_initialized = false;
/* Used to avoid initialization races. */
static malloc_mutex_t init_lock = {_SPINLOCK_INITIALIZER};
/******************************************************************************/
/*
* Statistics data structures.
@ -2969,12 +2973,6 @@ static inline bool
malloc_init(void)
{
/*
* We always initialize before threads are created, since any thread
* creation first triggers allocations.
*/
assert(__isthreaded == 0 || malloc_initialized);
if (malloc_initialized == false)
return (malloc_init_hard());
@ -2989,6 +2987,16 @@ malloc_init_hard(void)
char buf[PATH_MAX + 1];
const char *opts;
malloc_mutex_lock(&init_lock);
if (malloc_initialized) {
/*
* Another thread initialized the allocator before this one
* acquired init_lock.
*/
malloc_mutex_unlock(&init_lock);
return (false);
}
/* Get number of CPUs. */
{
int mib[2];
@ -3339,8 +3347,10 @@ malloc_init_hard(void)
/* Allocate and initialize arenas. */
arenas = (arena_t **)base_alloc(sizeof(arena_t *) * narenas);
if (arenas == NULL)
if (arenas == NULL) {
malloc_mutex_unlock(&init_lock);
return (true);
}
/*
* Zero the array. In practice, this should always be pre-zeroed,
* since it was just mmap()ed, but let's be sure.
@ -3352,12 +3362,15 @@ malloc_init_hard(void)
* arena_choose_hard().
*/
arenas_extend(0);
if (arenas[0] == NULL)
if (arenas[0] == NULL) {
malloc_mutex_unlock(&init_lock);
return (true);
}
malloc_mutex_init(&arenas_mtx);
malloc_initialized = true;
malloc_mutex_unlock(&init_lock);
return (false);
}