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make process init race free (issue #701)

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This commit is contained in:
Daan Leijen 2023-03-20 13:55:39 -07:00
parent 30df80b05a
commit 0b4c3da2e9
2 changed files with 11 additions and 1 deletions
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9
include/mimalloc/atomic.h
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@ -275,6 +275,15 @@ static inline intptr_t mi_atomic_subi(_Atomic(intptr_t)*p, intptr_t sub) {
return (intptr_t)mi_atomic_addi(p, -sub);
}
typedef _Atomic(uintptr_t) mi_atomic_once_t;
// Returns true only on the first invocation
static inline bool mi_atomic_once( mi_atomic_once_t* once ) {
if (mi_atomic_load_relaxed(once) != 0) return false; // quick test
uintptr_t expected = 0;
return mi_atomic_cas_strong_acq_rel(once, &expected, 1); // try to set to 1
}
// Yield
#if defined(__cplusplus)
#include <thread>

3
src/init.c
View File

@ -511,7 +511,8 @@ static void mi_detect_cpu_features(void) {
// Initialize the process; called by thread_init or the process loader
void mi_process_init(void) mi_attr_noexcept {
// ensure we are called once
if (_mi_process_is_initialized) return;
static mi_atomic_once_t process_init;
if (!mi_atomic_once(&process_init)) return;
_mi_verbose_message("process init: 0x%zx\n", _mi_thread_id());
_mi_process_is_initialized = true;
mi_process_setup_auto_thread_done();