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Fix nsync_mu_unlock_slow_() on Apple Silicon

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We torture test dlmalloc() in test/libc/stdio/memory_test.c. That test
was crashing on occasion on Apple M1 microprocessors when dlmalloc was
using *NSYNC locks. It was relatively easy to spot the cause, which is
this one particular compare and swap operation, which needed to change
to use sequentially-consistent ordering rather than an acquire barrier
This commit is contained in:
Justine Tunney 2023-11-13 10:57:02 -08:00
parent 3b15d31247
commit 751d20d98d
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GPG key ID: BE714B4575D6E328
5 changed files with 36 additions and 2 deletions
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23
third_party/dlmalloc/locks.inc vendored
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@ -30,6 +30,8 @@
*/
#ifdef USE_SPIN_LOCKS
#define MLOCK_T atomic_uint
static int malloc_wipe(MLOCK_T *lk) {
@ -51,6 +53,27 @@ static int malloc_unlock(MLOCK_T *lk) {
return 0;
}
#else
#define MLOCK_T nsync_mu
static int malloc_wipe(MLOCK_T *lk) {
bzero(lk, sizeof(*lk));
return 0;
}
static int malloc_lock(MLOCK_T *lk) {
nsync_mu_lock(lk);
return 0;
}
static int malloc_unlock(MLOCK_T *lk) {
nsync_mu_unlock(lk);
return 0;
}
#endif
#define ACQUIRE_LOCK(lk) malloc_lock(lk)
#define RELEASE_LOCK(lk) malloc_unlock(lk)
#define INITIAL_LOCK(lk) malloc_wipe(lk)