diff options
| author | Thomas Rodgers <rodgert@twrodgers.com> | 2021-04-21 18:12:03 -0700 |
|---|---|---|
| committer | Thomas Rodgers <rodgert@twrodgers.com> | 2021-04-22 07:34:02 -0700 |
| commit | ae2f6e01749f39b8b8ccc211fc29e5e6ec8b57cd (patch) | |
| tree | faa679184d18d0f257388228947b4347d7757b00 | |
| parent | 0cda606d08d6196b76524c7b6ad51d87fed0d54b (diff) | |
| download | gcc-ae2f6e01749f39b8b8ccc211fc29e5e6ec8b57cd.zip gcc-ae2f6e01749f39b8b8ccc211fc29e5e6ec8b57cd.tar.gz gcc-ae2f6e01749f39b8b8ccc211fc29e5e6ec8b57cd.tar.bz2 | |
libstdc++: Fix "bare" notifications dropped by waiters check
For types that track whether or not there extant waiters (e.g.
semaphore) internally, the __atomic_notify_address_bare() call was
introduced to avoid the overhead of loading the atomic count of
waiters. For platforms that don't have Futex, however, there was
still a check for waiters, and seeing that there are none (because
in the bare case, the count is not incremented), the notification
is dropped. This commit addresses that case.
libstdc++-v3/ChangeLog:
* include/bits/atomic_wait.h: Always notify waiters in the
case of 'bare' address notification.
| -rw-r--r-- | libstdc++-v3/include/bits/atomic_wait.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/libstdc++-v3/include/bits/atomic_wait.h b/libstdc++-v3/include/bits/atomic_wait.h index 0ac5575..984ed70 100644 --- a/libstdc++-v3/include/bits/atomic_wait.h +++ b/libstdc++-v3/include/bits/atomic_wait.h @@ -226,9 +226,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } void - _M_notify(const __platform_wait_t* __addr, bool __all) noexcept + _M_notify(const __platform_wait_t* __addr, bool __all, bool __bare) noexcept { - if (!_M_waiting()) + if (!(__bare || _M_waiting())) return; #ifdef _GLIBCXX_HAVE_PLATFORM_WAIT @@ -304,11 +304,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } void - _M_notify(bool __all) + _M_notify(bool __all, bool __bare = false) { if (_M_addr == &_M_w._M_ver) __atomic_fetch_add(_M_addr, 1, __ATOMIC_ACQ_REL); - _M_w._M_notify(_M_addr, __all); + _M_w._M_notify(_M_addr, __all, __bare); } template<typename _Up, typename _ValFn, @@ -452,7 +452,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __atomic_notify_address(const _Tp* __addr, bool __all) noexcept { __detail::__bare_wait __w(__addr); - __w._M_notify(__all); + __w._M_notify(__all, true); } // This call is to be used by atomic types which track contention externally @@ -464,7 +464,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __detail::__platform_notify(__addr, __all); #else __detail::__bare_wait __w(__addr); - __w._M_notify(__all); + __w._M_notify(__all, true); #endif } _GLIBCXX_END_NAMESPACE_VERSION |