From 1315faa9a01c8d768fd750ed643bae4f3eefc48a Mon Sep 17 00:00:00 2001 From: Yura Sokolov Date: Tue, 13 May 2025 18:57:46 +0300 Subject: [PATCH v1] Make SpinLockAcquire and SpinLockRelease full memory barriers. Andres Freund stated SpinLockAcquire is used as a full memory barrier at least once [1]. Code comment in spin.h also states: > Load and stores operation in calling code are guaranteed not to be > reordered with respect to these operations, because they include a > compiler barrier. But ARM/ARM64 code used __spin_lock_test_and_set and __spin_lock_release which only have acquire and release semantics respectively. Fix it by adding __sync_synchronize before __sync_lock_test_and_set and after __sync_lock_release. --- src/include/storage/s_lock.h | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h index 2f73f9fcf57..7ee94302df1 100644 --- a/src/include/storage/s_lock.h +++ b/src/include/storage/s_lock.h @@ -258,10 +258,14 @@ typedef int slock_t; static __inline__ int tas(volatile slock_t *lock) { + __sync_synchronize(); return __sync_lock_test_and_set(lock, 1); } -#define S_UNLOCK(lock) __sync_lock_release(lock) +#define S_UNLOCK(lock) do { \ + __sync_lock_release(lock); \ + __sync_synchronize(); \ +} while(0) #if defined(__aarch64__) @@ -543,10 +547,14 @@ typedef int slock_t; static __inline__ int tas(volatile slock_t *lock) { + __sync_synchronize(); return __sync_lock_test_and_set(lock, 1); } -#define S_UNLOCK(lock) __sync_lock_release(lock) +#define S_UNLOCK(lock) do { \ + __sync_lock_release(lock); \ + __sync_synchronize(); \ +} while(0) #elif defined(HAVE_GCC__SYNC_CHAR_TAS) #define HAS_TEST_AND_SET @@ -558,10 +566,14 @@ typedef char slock_t; static __inline__ int tas(volatile slock_t *lock) { + __sync_synchronize(); return __sync_lock_test_and_set(lock, 1); } -#define S_UNLOCK(lock) __sync_lock_release(lock) +#define S_UNLOCK(lock) do { \ + __sync_lock_release(lock); \ + __sync_synchronize(); \ +} while(0) #endif /* HAVE_GCC__SYNC_INT32_TAS */ -- 2.43.0