From 18aab9241fad1238171b1d849f7765ec6100c593 Mon Sep 17 00:00:00 2001
From: Michael Lee <mzlee@fb.com>
Date: Wed, 10 Aug 2016 16:45:18 -0700
Subject: [PATCH] Gate SysMembarrier to not FOLLY_MOBILE platforms

Summary: Gate `kIsLinux` to not include `FOLLY_MOBILE` because "mobile" linux does not really behave like real linux.

Differential Revision: D3697717

fbshipit-source-id: 1b0f4208d2f71c35399c30f20a71bfa4ba4724e8
---
 folly/Portability.h                 |  2 +-
 folly/portability/SysMembarrier.cpp | 10 ++++++----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/folly/Portability.h b/folly/Portability.h
index 5776a007..56dc7c95 100644
--- a/folly/Portability.h
+++ b/folly/Portability.h
@@ -357,7 +357,7 @@ using namespace FOLLY_GFLAGS_NAMESPACE;
 
 namespace folly {
 
-#ifdef __linux__
+#if defined(__linux__) && !FOLLY_MOBILE
 constexpr auto kIsLinux = true;
 #else
 constexpr auto kIsLinux = false;
diff --git a/folly/portability/SysMembarrier.cpp b/folly/portability/SysMembarrier.cpp
index cc4b43ac..9a3d3073 100644
--- a/folly/portability/SysMembarrier.cpp
+++ b/folly/portability/SysMembarrier.cpp
@@ -22,12 +22,14 @@
 #include <folly/portability/SysSyscall.h>
 #include <folly/portability/Unistd.h>
 
-#if !defined(__NR_membarrier) && FOLLY_X64 && !FOLLY_MOBILE && \
-    defined(__linux__)
+#if FOLLY_X64 && !FOLLY_MOBILE && defined(__linux__)
+#define FOLLY_USE_SYS_MEMBARRIER 1
+#if !defined(__NR_membarrier)
 #define __NR_membarrier 324
 #define MEMBARRIER_CMD_QUERY 0
 #define MEMBARRIER_CMD_SHARED 1
 #endif
+#endif
 
 namespace folly {
 namespace detail {
@@ -37,7 +39,7 @@ bool sysMembarrierAvailable() {
     return false;
   }
 
-#ifdef __NR_membarrier
+#if FOLLY_USE_SYS_MEMBARRIER
   auto r = syscall(__NR_membarrier, MEMBARRIER_CMD_QUERY, /* flags = */ 0);
   if (r == -1) {
     return false;
@@ -50,7 +52,7 @@ bool sysMembarrierAvailable() {
 }
 
 int sysMembarrier() {
-#ifdef __NR_membarrier
+#if FOLLY_USE_SYS_MEMBARRIER
   return syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, /* flags = */ 0);
 #else
   return -1;
-- 
2.34.1