From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id DF1FD3858438; Sun, 20 Feb 2022 06:04:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DF1FD3858438 From: "danregister at poczta dot fm" To: gcc-bugs@gcc.gnu.org Subject: [Bug sanitizer/101978] thread sanitizer false positive when condition variable Date: Sun, 20 Feb 2022 06:04:37 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: sanitizer X-Bugzilla-Version: 11.1.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: danregister at poczta dot fm X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Feb 2022 06:04:38 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101978 Daniel Adamski changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |danregister at poczta dot = fm --- Comment #3 from Daniel Adamski --- (g++ (Debian 11.2.0-14) 11.2.0) I believe it is wait_for() in particular. This works fine: #include #include #include #include using namespace std::chrono_literals; std::mutex mtx; std::condition_variable cv; void run1() { std::unique_lock lck{mtx}; cv.wait(lck); } void run2() { std::unique_lock lck{mtx}; std::this_thread::sleep_for(500ms); cv.notify_all(); } int main() { std::jthread th1{ run1 }; std::jthread th2{ run2 }; } But replace: - cv.wait(lck); + cv.wait_for(lck, 1s); and you get "double lock": =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D WARNING: ThreadSanitizer: double lock of a mutex (pid=3D644005) #0 pthread_mutex_lock ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors= .inc:4240 (libtsan.so.0+0x4f30a) #1 __gthread_mutex_lock /usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:749 (a.out+0x27bf) #2 std::mutex::lock() /usr/include/c++/11/bits/std_mutex.h:100 (a.out+0x2844) #3 std::unique_lock::lock() /usr/include/c++/11/bits/unique_lock.h:139 (a.out+0x422d) #4 std::unique_lock::unique_lock(std::mutex&) /usr/include/c++/11/bits/unique_lock.h:69 (a.out+0x3ce2) #5 run2() /tmp/tsanmy.cpp:16 (a.out+0x241d) #6 void std::__invoke_impl(std::__invoke_other, void (*&&)()) /usr/include/c++/11/bits/invoke.h:61 (a.out+0x5550) #7 std::__invoke_result::type std::__invoke(void (*&&)()) /usr/include/c++/11/bits/invoke.h:96 (a.out+0x54b5) #8 void std::thread::_Invoker >::_M_invoke<0ul>(std::_Index_tuple<0ul>) /usr/include/c++/11/bits/std_thread.h:253 (a.out+0x541a) #9 std::thread::_Invoker >::operator()() /usr/include/c++/11/bits/std_thread.h:260 (a.out+0x53c4) #10 std::thread::_State_impl > >::_M_run() /usr/include/c++/11/bits/std_thread.h:211 (a.out+0x537e) #11 (libstdc++.so.6+0xd38f3) Location is global 'mtx' of size 40 at 0x56501849e160 (a.out+0x0000000091= 60) Mutex M10 (0x56501849e160) created at: #0 pthread_mutex_lock ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors= .inc:4240 (libtsan.so.0+0x4f30a) #1 __gthread_mutex_lock /usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:749 (a.out+0x27bf) #2 std::mutex::lock() /usr/include/c++/11/bits/std_mutex.h:100 (a.out+0x2844) #3 std::unique_lock::lock() /usr/include/c++/11/bits/unique_lock.h:139 (a.out+0x422d) #4 std::unique_lock::unique_lock(std::mutex&) /usr/include/c++/11/bits/unique_lock.h:69 (a.out+0x3ce2) #5 run1() /tmp/tsanmy.cpp:11 (a.out+0x2392) #6 void std::__invoke_impl(std::__invoke_other, void (*&&)()) /usr/include/c++/11/bits/invoke.h:61 (a.out+0x5550) #7 std::__invoke_result::type std::__invoke(void (*&&)()) /usr/include/c++/11/bits/invoke.h:96 (a.out+0x54b5) #8 void std::thread::_Invoker >::_M_invoke<0ul>(std::_Index_tuple<0ul>) /usr/include/c++/11/bits/std_thread.h:253 (a.out+0x541a) #9 std::thread::_Invoker >::operator()() /usr/include/c++/11/bits/std_thread.h:260 (a.out+0x53c4) #10 std::thread::_State_impl > >::_M_run() /usr/include/c++/11/bits/std_thread.h:211 (a.out+0x537e) #11 (libstdc++.so.6+0xd38f3) SUMMARY: ThreadSanitizer: double lock of a mutex /usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:749 in __gthread_mutex_lock=