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.