On 24/11/20 23:45 +0000, Jonathan Wakely wrote:
On 21/11/20 16:36 -0800, H.J. Lu wrote:
On Sat, Nov 21, 2020 at 9:40 AM Jonathan Wakely via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
On 21/11/20 17:04 +0000, Jonathan Wakely wrote:
On 21/11/20 16:16 +0100, Andreas Schwab wrote:
In file included from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/shared_ptr_atomic.h:33,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/memory:78,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/m68k-linux/bits/stdc++.h:82,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/m68k-linux/bits/extc++.h:32,
from
/daten/aranym/gcc/gcc-20201121/libstdc++-v3/testsuite/17_intro/headers/c++2020/all_attributes.cc:37:
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/atomic_base.h:
In member function 'void std::atomic_flag::wait(bool, std::memory_order)
const':
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/atomic_base.h:239:
error: no matching function for call to '__atomic_wait(const __atomic_flag_data_type*,
bool&, std::atomic_flag::wait(bool, std::memory_order) const::<lambda()>)'
In file included from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/atomic_base.h:41,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/shared_ptr_atomic.h:33,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/memory:78,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/m68k-linux/bits/stdc++.h:82,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/m68k-linux/bits/extc++.h:32,
from
/daten/aranym/gcc/gcc-20201121/libstdc++-v3/testsuite/17_intro/headers/c++2020/all_attributes.cc:37:
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/atomic_wait.h:265:
note: candidate: 'template<class _Tp, class _Pred> void
std::__atomic_wait(const _Tp*, _Tp, _Pred)'
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/atomic_wait.h:265:
note: template argument deduction/substitution failed:
In file included from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/shared_ptr_atomic.h:33,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/memory:78,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/m68k-linux/bits/stdc++.h:82,
from
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/m68k-linux/bits/extc++.h:32,
from
/daten/aranym/gcc/gcc-20201121/libstdc++-v3/testsuite/17_intro/headers/c++2020/all_attributes.cc:37:
/daten/aranym/gcc/gcc-20201121/Build/m68k-linux/libstdc++-v3/include/bits/atomic_base.h:239:
note: deduced conflicting types for parameter '_Tp' ('unsigned char' and
'bool')
I'm testing this.
I'm committing this instead, it's the same but also disables
29_atomics/atomic/wait_notify/generic.cc on non-linux targets.
Tested sparc-solaris2.11 and powerpc64le-linux.
There are still some timeouts on linux:
FAIL: 30_threads/latch/3.cc execution test
FAIL: 30_threads/semaphore/try_acquire_for.cc execution test
I opened:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97936
I've disabled the failing tests for now. They can be re-enabled after
the problem is found and fixed.
I was finally able to reproduce the hangs, and I think this is the
fix:
--- a/libstdc++-v3/include/bits/atomic_wait.h
+++ b/libstdc++-v3/include/bits/atomic_wait.h
@@ -100,9 +100,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
auto __e = syscall (SYS_futex, static_cast<const void*>(__addr),
static_cast<int>(__futex_wait_flags::__wait_private),
__val, nullptr);
- if (!__e)
+ if (!__e || errno == EAGAIN)
break;
- else if (!(errno == EINTR || errno == EAGAIN))
+ else if (errno != EINTR)
__throw_system_error(__e);
}
}
The problem is that we're going into a busy loop when SYS_futex
returns EAGAIN, but that means the current value doesn't match the
expected value, so we should return not keep waiting for the value to
change.
