From 2d4571bf3060f8f3d8417a0ec55e21a280158069 Mon Sep 17 00:00:00 2001 From: Joachim Protze Date: Mon, 13 Jan 2020 22:24:00 -1000 Subject: [PATCH] [OpenMP][Tool] Runtime warning for missing TSan-option TSan spuriously reports for any OpenMP application a race on the initialization of a runtime internal mutex: ``` Atomic read of size 1 at 0x7b6800005940 by thread T4: #0 pthread_mutex_lock (a.out+0x43f39e) #1 __kmp_resume_64 (libomp.so.5+0x84db4) Previous write of size 1 at 0x7b6800005940 by thread T7: #0 pthread_mutex_init (a.out+0x424793) #1 __kmp_suspend_initialize_thread (libomp.so.5+0x8422e) ``` According to @AndreyChurbanov this is a false positive report, as the control flow of the runtime guarantees the ordering of the mutex initialization and the lock: https://software.intel.com/en-us/forums/intel-open-source-openmp-runtime-library/topic/530363 To suppress this report, I suggest the use of TSAN_OPTIONS='ignore_uninstrumented_modules=1'. With this patch, a runtime warning is provided in case an OpenMP application is built with Tsan and executed without this Tsan-option. Reviewed By: jdoerfert Differential Revision: https://reviews.llvm.org/D70412 --- openmp/CREDITS.txt | 4 ++++ openmp/tools/archer/ompt-tsan.cpp | 34 +++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/openmp/CREDITS.txt b/openmp/CREDITS.txt index b14bb9a1e6e60b..ede45b10fea252 100644 --- a/openmp/CREDITS.txt +++ b/openmp/CREDITS.txt @@ -53,6 +53,10 @@ N: Steven Noonan E: steven@uplinklabs.net D: Patches for the ARM architecture and removal of several inconsistencies. +N: Joachim Protze +E: protze@itc.rwth-aachen.de +D: OpenMP Tools Interface, Archer tool + N: Alp Toker E: alp@nuanti.com D: Making build work for FreeBSD. diff --git a/openmp/tools/archer/ompt-tsan.cpp b/openmp/tools/archer/ompt-tsan.cpp index 03a2f6c148fe39..50b98e2a485196 100644 --- a/openmp/tools/archer/ompt-tsan.cpp +++ b/openmp/tools/archer/ompt-tsan.cpp @@ -82,6 +82,31 @@ class ArcherFlags { } }; +class TsanFlags { +public: + int ignore_noninstrumented_modules; + + TsanFlags(const char *env) : ignore_noninstrumented_modules(0) { + if (env) { + std::vector tokens; + std::string token; + std::string str(env); + std::istringstream iss(str); + while (std::getline(iss, token, ' ')) + tokens.push_back(token); + + for (std::vector::iterator it = tokens.begin(); + it != tokens.end(); ++it) { + // we are interested in ignore_noninstrumented_modules to print a + // warning + if (sscanf(it->c_str(), "ignore_noninstrumented_modules=%d", + &ignore_noninstrumented_modules)) + continue; + } + } + } +}; + #if (LLVM_VERSION) >= 40 extern "C" { int __attribute__((weak)) __archer_get_omp_status(); @@ -89,6 +114,7 @@ void __attribute__((weak)) __tsan_flush_memory() {} } #endif ArcherFlags *archer_flags; +TsanFlags *tsan_flags; // The following definitions are pasted from "llvm/Support/Compiler.h" to allow // the code @@ -838,6 +864,8 @@ static int ompt_tsan_initialize(ompt_function_lookup_t lookup, ompt_data_t *tool_data) { const char *options = getenv("ARCHER_OPTIONS"); archer_flags = new ArcherFlags(options); + options = getenv("TSAN_OPTIONS"); + tsan_flags = new TsanFlags(options); ompt_set_callback_t ompt_set_callback = (ompt_set_callback_t)lookup("ompt_set_callback"); @@ -869,6 +897,12 @@ static int ompt_tsan_initialize(ompt_function_lookup_t lookup, SET_CALLBACK_T(mutex_acquired, mutex); SET_CALLBACK_T(mutex_released, mutex); SET_OPTIONAL_CALLBACK_T(reduction, sync_region, hasReductionCallback, ompt_set_never); + + if (!tsan_flags->ignore_noninstrumented_modules) + fprintf( + stderr, + "Warning: please export TSAN_OPTIONS='ignore_noninstrumented_modules=1' " + "to avoid false positive reports from the OpenMP runtime.!\n"); return 1; // success }