From 3b7658a4752e1332c684ad757686ce9ee0e5fbd1 Mon Sep 17 00:00:00 2001
From: Mike Klein <mtklein@chromium.org>
Date: Wed, 20 Sep 2017 09:53:39 -0400
Subject: Teach TSAN directly about semaphore_t.

Instead of teaching TSAN than SkMutex is a lock to get around it not
understanding Mach semaphore_t routines, teach it that there is a
happens-before relationship between semaphore_signal() and
semaphore_wait().

This reverts commit e395bf2d189e22822ddf2b46541c510d6d8fbcc0.
New changes are entirely restricted to SkSemaphore.cpp.

Change-Id: I27f647b93c48e81e8327db849881d669c4cd3d04
Reviewed-on: https://skia-review.googlesource.com/49180
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
---
 src/core/SkSemaphore.cpp   | 23 ++++++++++++++++--
 src/core/SkSharedMutex.cpp | 60 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 80 insertions(+), 3 deletions(-)

(limited to 'src/core')

diff --git a/src/core/SkSemaphore.cpp b/src/core/SkSemaphore.cpp
index f8f6e165ad..6ad10c4317 100644
--- a/src/core/SkSemaphore.cpp
+++ b/src/core/SkSemaphore.cpp
@@ -10,6 +10,17 @@
 
 #if defined(SK_BUILD_FOR_MAC) || defined(SK_BUILD_FOR_IOS)
     #include <mach/mach.h>
+
+    // We've got to teach TSAN that there is a happens-before edge beteween
+    // semaphore_signal() and semaphore_wait().
+    #if __has_feature(thread_sanitizer)
+        extern "C" void AnnotateHappensBefore(const char*, int, void*);
+        extern "C" void AnnotateHappensAfter (const char*, int, void*);
+    #else
+        static void AnnotateHappensBefore(const char*, int, void*) {}
+        static void AnnotateHappensAfter (const char*, int, void*) {}
+    #endif
+
     struct SkBaseSemaphore::OSSemaphore {
         semaphore_t fSemaphore;
 
@@ -18,8 +29,16 @@
         }
         ~OSSemaphore() { semaphore_destroy(mach_task_self(), fSemaphore); }
 
-        void signal(int n) { while (n --> 0) { semaphore_signal(fSemaphore); } }
-        void wait() { semaphore_wait(fSemaphore); }
+        void signal(int n) {
+            while (n --> 0) {
+                AnnotateHappensBefore(__FILE__, __LINE__, &fSemaphore);
+                semaphore_signal(fSemaphore);
+            }
+        }
+        void wait() {
+            semaphore_wait(fSemaphore);
+            AnnotateHappensAfter(__FILE__, __LINE__, &fSemaphore);
+        }
     };
 #elif defined(SK_BUILD_FOR_WIN32)
     struct SkBaseSemaphore::OSSemaphore {
diff --git a/src/core/SkSharedMutex.cpp b/src/core/SkSharedMutex.cpp
index 8d6738f9e4..17714a7185 100644
--- a/src/core/SkSharedMutex.cpp
+++ b/src/core/SkSharedMutex.cpp
@@ -8,10 +8,68 @@
 #include "SkSharedMutex.h"
 
 #include "SkAtomics.h"
-#include "SkTSAN.h"
 #include "SkTypes.h"
 #include "SkSemaphore.h"
 
+#if !defined(__has_feature)
+    #define __has_feature(x) 0
+#endif
+
+#if __has_feature(thread_sanitizer)
+
+    /* Report that a lock has been created at address "lock". */
+    #define ANNOTATE_RWLOCK_CREATE(lock) \
+        AnnotateRWLockCreate(__FILE__, __LINE__, lock)
+
+    /* Report that the lock at address "lock" is about to be destroyed. */
+    #define ANNOTATE_RWLOCK_DESTROY(lock) \
+        AnnotateRWLockDestroy(__FILE__, __LINE__, lock)
+
+    /* Report that the lock at address "lock" has been acquired.
+       is_w=1 for writer lock, is_w=0 for reader lock. */
+    #define ANNOTATE_RWLOCK_ACQUIRED(lock, is_w) \
+        AnnotateRWLockAcquired(__FILE__, __LINE__, lock, is_w)
+
+    /* Report that the lock at address "lock" is about to be released. */
+    #define ANNOTATE_RWLOCK_RELEASED(lock, is_w) \
+      AnnotateRWLockReleased(__FILE__, __LINE__, lock, is_w)
+
+    #if defined(DYNAMIC_ANNOTATIONS_WANT_ATTRIBUTE_WEAK)
+        #if defined(__GNUC__)
+            #define DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK __attribute__((weak))
+        #else
+            /* TODO(glider): for Windows support we may want to change this macro in order
+               to prepend __declspec(selectany) to the annotations' declarations. */
+            #error weak annotations are not supported for your compiler
+        #endif
+    #else
+        #define DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK
+    #endif
+
+    extern "C" {
+    void AnnotateRWLockCreate(
+        const char *file, int line,
+        const volatile void *lock) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    void AnnotateRWLockDestroy(
+        const char *file, int line,
+        const volatile void *lock) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    void AnnotateRWLockAcquired(
+        const char *file, int line,
+        const volatile void *lock, long is_w) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    void AnnotateRWLockReleased(
+        const char *file, int line,
+        const volatile void *lock, long is_w) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    }
+
+#else
+
+    #define ANNOTATE_RWLOCK_CREATE(lock)
+    #define ANNOTATE_RWLOCK_DESTROY(lock)
+    #define ANNOTATE_RWLOCK_ACQUIRED(lock, is_w)
+    #define ANNOTATE_RWLOCK_RELEASED(lock, is_w)
+
+#endif
+
 #ifdef SK_DEBUG
 
     #include "SkThreadID.h"
-- 
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