From 466423b15732af074d9010b09c579f3918fc225f Mon Sep 17 00:00:00 2001 From: David Klempner Date: Wed, 11 Mar 2015 15:00:46 -0700 Subject: Add a no_barrier_load atomic operation. Use this to relax the acq_loads in some fd_posix assertions. The primary goal here is to avoid masking potential iomgr races from tsan. --- include/grpc/support/atm_gcc_atomic.h | 1 + include/grpc/support/atm_gcc_sync.h | 11 ++++++++++- include/grpc/support/atm_win32.h | 5 +++++ 3 files changed, 16 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/grpc/support/atm_gcc_atomic.h b/include/grpc/support/atm_gcc_atomic.h index 11d78b4097..65d3d0c60f 100644 --- a/include/grpc/support/atm_gcc_atomic.h +++ b/include/grpc/support/atm_gcc_atomic.h @@ -43,6 +43,7 @@ typedef gpr_intptr gpr_atm; #define gpr_atm_full_barrier() (__atomic_thread_fence(__ATOMIC_SEQ_CST)) #define gpr_atm_acq_load(p) (__atomic_load_n((p), __ATOMIC_ACQUIRE)) +#define gpr_atm_no_barrier_load(p) (__atomic_load_n((p), __ATOMIC_RELAXED)) #define gpr_atm_rel_store(p, value) \ (__atomic_store_n((p), (gpr_intptr)(value), __ATOMIC_RELEASE)) diff --git a/include/grpc/support/atm_gcc_sync.h b/include/grpc/support/atm_gcc_sync.h index e863bfd4c1..4955e4436f 100644 --- a/include/grpc/support/atm_gcc_sync.h +++ b/include/grpc/support/atm_gcc_sync.h @@ -40,9 +40,11 @@ typedef gpr_intptr gpr_atm; +#define GPR_ATM_COMPILE_BARRIER_() __asm__ __volatile__("" : : : "memory") + #if defined(__i386) || defined(__x86_64__) /* All loads are acquire loads and all stores are release stores. */ -#define GPR_ATM_LS_BARRIER_() __asm__ __volatile__("" : : : "memory") +#define GPR_ATM_LS_BARRIER_() GPR_ATM_COMPILE_BARRIER_() #else #define GPR_ATM_LS_BARRIER_() gpr_atm_full_barrier() #endif @@ -55,12 +57,19 @@ static __inline gpr_atm gpr_atm_acq_load(const gpr_atm *p) { return value; } +static __inline gpr_atm gpr_atm_no_barrier_load(const gpr_atm *p) { + gpr_atm value = *p; + GPR_ATM_COMPILE_BARRIER_(); + return value; +} + static __inline void gpr_atm_rel_store(gpr_atm *p, gpr_atm value) { GPR_ATM_LS_BARRIER_(); *p = value; } #undef GPR_ATM_LS_BARRIER_ +#undef GPR_ATM_COMPILE_BARRIER_ #define gpr_atm_no_barrier_fetch_add(p, delta) \ gpr_atm_full_fetch_add((p), (delta)) diff --git a/include/grpc/support/atm_win32.h b/include/grpc/support/atm_win32.h index 3b9113c28b..18bf372004 100644 --- a/include/grpc/support/atm_win32.h +++ b/include/grpc/support/atm_win32.h @@ -49,6 +49,11 @@ static __inline gpr_atm gpr_atm_acq_load(const gpr_atm *p) { return result; } +static __inline gpr_atm gpr_atm_no_barrier_load(const gpr_atm *p) { + /* TODO(dklempner): Can we implement something better here? */ + gpr_atm_acq_load(p); +} + static __inline void gpr_atm_rel_store(gpr_atm *p, gpr_atm value) { gpr_atm_full_barrier(); *p = value; -- cgit v1.2.3