From 7eeb8c04e53fa880ee559efb727517ce778d17a0 Mon Sep 17 00:00:00 2001 From: Thomas Rodgers Date: Wed, 21 Apr 2021 10:01:06 -0700 Subject: [PATCH] [libstdc++] Fix test timeout in stop_calback/destroy.cc A change was made to __atomic_semaphore::_S_do_try_acquire() to (ideally) let the compare_exchange reload the value of __old rather than always reloading it twice. This causes _M_acquire to spin indefinitely if the value of __old is already 0. libstdc++-v3/ChangeLog: * include/bits/semaphore_base.h: Always reload __old in __atomic_semaphore::_S_do_try_acquire(). * testsuite/30_threads/stop_token/stop_callback/destroy.cc: re-enable testcase. --- libstdc++-v3/include/bits/semaphore_base.h | 16 ++++++---------- .../stop_token/stop_callback/destroy.cc | 2 -- 2 files changed, 6 insertions(+), 12 deletions(-) diff --git a/libstdc++-v3/include/bits/semaphore_base.h b/libstdc++-v3/include/bits/semaphore_base.h index 35469e443b0..84b33423fff 100644 --- a/libstdc++-v3/include/bits/semaphore_base.h +++ b/libstdc++-v3/include/bits/semaphore_base.h @@ -196,9 +196,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __atomic_semaphore& operator=(const __atomic_semaphore&) = delete; static _GLIBCXX_ALWAYS_INLINE bool - _S_do_try_acquire(__detail::__platform_wait_t* __counter, - __detail::__platform_wait_t& __old) noexcept + _S_do_try_acquire(__detail::__platform_wait_t* __counter) noexcept { + auto __old = __atomic_impl::load(__counter, memory_order::acquire); if (__old == 0) return false; @@ -211,18 +211,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _GLIBCXX_ALWAYS_INLINE void _M_acquire() noexcept { - auto __old = __atomic_impl::load(&_M_counter, memory_order::acquire); auto const __pred = - [this, &__old] { return _S_do_try_acquire(&this->_M_counter, __old); }; + [this] { return _S_do_try_acquire(&this->_M_counter); }; std::__atomic_wait_address_bare(&_M_counter, __pred); } bool _M_try_acquire() noexcept { - auto __old = __atomic_impl::load(&_M_counter, memory_order::acquire); auto const __pred = - [this, &__old] { return _S_do_try_acquire(&this->_M_counter, __old); }; + [this] { return _S_do_try_acquire(&this->_M_counter); }; return std::__detail::__atomic_spin(__pred); } @@ -231,9 +229,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _M_try_acquire_until(const chrono::time_point<_Clock, _Duration>& __atime) noexcept { - auto __old = __atomic_impl::load(&_M_counter, memory_order_relaxed); auto const __pred = - [this, &__old] { return _S_do_try_acquire(&this->_M_counter, __old); }; + [this] { return _S_do_try_acquire(&this->_M_counter); }; return __atomic_wait_address_until_bare(&_M_counter, __pred, __atime); } @@ -243,9 +240,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _M_try_acquire_for(const chrono::duration<_Rep, _Period>& __rtime) noexcept { - auto __old = __atomic_impl::load(&_M_counter, memory_order_relaxed); auto const __pred = - [this, &__old] { return _S_do_try_acquire(&this->_M_counter, __old); }; + [this] { return _S_do_try_acquire(&this->_M_counter); }; return __atomic_wait_address_for_bare(&_M_counter, __pred, __rtime); } diff --git a/libstdc++-v3/testsuite/30_threads/stop_token/stop_callback/destroy.cc b/libstdc++-v3/testsuite/30_threads/stop_token/stop_callback/destroy.cc index c2cfba027cb..061ed448c33 100644 --- a/libstdc++-v3/testsuite/30_threads/stop_token/stop_callback/destroy.cc +++ b/libstdc++-v3/testsuite/30_threads/stop_token/stop_callback/destroy.cc @@ -21,8 +21,6 @@ // { dg-require-effective-target pthread } // { dg-require-gthreads "" } -// { dg-skip-if "FIXME: times out" { *-*-* } } - #include #include #include