On Tue, Jul 04, 2023 at 04:25:45PM -0400, Alan Stern wrote: > On Tue, Jul 04, 2023 at 01:19:23PM -0400, Olivier Dion wrote: [ . . . ] > > I am puzzled by this. Initialization of a shared variable does not need > > to be atomic until its publication. Could you expand on this? > > In the kernel, I believe it sometimes happens that an atomic variable > may be published before it is initialized. (If that's wrong, Paul or > Peter can correct me.) But since this doesn't apply to the situations > you're concerned with, you can forget I mentioned it. Both use cases exist. A global atomic is implicitly published at compile time. If the desired initial value is not known until multiple threads are running, then it is necessary to be careful. Hence double-check locking and its various replacements. (Clearly, if you can determine the initial value before going multithreaded, life is simpler.) And dynamically allocated or on-stack storage is the other case, where there is a point in time when the storage is private even after multiple threads are running. Or am I missing the point? Thanx, Paul
