Hello, On Thu, Oct 17, 2019 at 02:29:46AM +1100, Aleksa Sarai wrote: > > Hah, where is it saying that? > > Isn't that what this says: > > > Therefore, if you find yourself only using the Non-RMW operations of > > atomic_t, you do not in fact need atomic_t at all and are doing it > > wrong. > > Doesn't using just atomic64_read() and atomic64_set() fall under "only > using the non-RMW operations of atomic_t"? But yes, I agree that any > locking is overkill. Yeah, I mean, it's an overkill. We can use seqlock or u64_stat here but it doesn't matter that much. > > > As for 64-bit on 32-bit machines -- that is a separate issue, but from > > > [1] it seems to me like there are more problems that *_ONCE() fixes than > > > just split reads and writes. > > > > Your explanations are too wishy washy. If you wanna fix it, please do > > it correctly. R/W ONCE isn't the right solution here. > > Sure, I will switch it to use atomic64_read() and atomic64_set() instead > if that's what you'd prefer. Though I will mention that on quite a few > architectures atomic64_read() is defined as: > > #define atomic64_read(v) READ_ONCE((v)->counter) Yeah, on archs which don't have split access on 64bits. On the ones which do, it does something else. The generic implementation is straight-up locking, I think. Thanks. -- tejun
