June 16, 2022 11:48 AM, "David Laight" <David.Laight@xxxxxxxxxx> wrote: > No wonder I was confused. > It's not surprising the compiler optimises it all away. > > It doesn't seem right to be 'abusing' WRITE_ONCE() here. > Just adding barrier() should be enough and much more descriptive. I had the same thought, although I do not believe barrier() is sufficient on its own. barrier_data() with a pointer to uc passed through is required to keep clang from eliminating the dead store. -- Thanks, Oliver