On Tue, Mar 15, 2016 at 10:32:45AM +0100, Ingo Molnar wrote: > 2) its naming sucks. "fetch_or()" does not really signal that it's a > fundamentally atomic operation, nor what API family it belongs to.
I disagree there, the fetch-$op naming is widely used for atomic operations that return the previous value. See for example the C/C++11 atomic ops. I've even thought about reworking our entire atomic*_t bits to match. That is, introduce all the fetch_$op primitives, then convert all the $op_return ones over and finally remove all the $op_return ones. I've not done so because we're all so very used to $op_return that I'm sure people (and this would very much include me) would curse me for changing this. The reason for fetch_$op is that it also works for irreversible operations like or. With or_return you simply cannot tell what the previous state was (with add_return you can do a simple subtraction to revert to the prior state). And yes, some people use the xchg-$op naming, but its less widely used (x86 asm being one). Other also use swap-$op. In any case, I prefer the name as it was.
