----- On Apr 19, 2021, at 5:41 AM, Duncan Sands baldr...@free.fr wrote:
> >> Quick question: should we use __atomic_load() or atomic_load_explicit() (C) >> and >> (std::atomic<__typeof__(x)>)(x)).load() (C++) ? > > If both are available, is there any advantage to using the C++ version when > compiling C++? As opposed to using the C11 one for both C and C++? I recently noticed that using C11/C++11 atomic load explicit is not a good fit for rcu_dereference, because we want the type to be a pointer, not an _Atomic type. gcc appears to accept a looser typing, but clang has issues trying to build that code. So I plan to use __atomic(p, v, __ATOMIC_CONSUME) instead in both C and C++. Also, I'll drop the cmm_smp_read_barrier_depends() when using __ATOMIC_CONSUME, because AFAIU their memory ordering semantics are redundant for rcu_dereference. Here is the resulting commit for review on gerrit: https://review.lttng.org/c/userspace-rcu/+/5455 Fix: use __atomic_load() rather than atomic load explicit [NEW] Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
