On Fri, Dec 11 2020 at 14:19, David Laight wrote:

From: Thomas Gleixner

quoted

You can't catch that. If this really becomes an issue you need a
sequence counter around it.

Or just two copies of the high word.
Provided the accesses are sequenced:
writer:
	load high:low
	add small_value,high:low
	store high
	store low
	store high_copy
reader:
	load high_copy
	load low
	load high
	if (high != high_copy)
		low = 0;

And low = 0 is solving what? You need to loop back and retry until it's
consistent and then it's nothing else than an open coded sequence count.

Thanks,

        tglx