Yang, On Tue, Nov 10, 2015 at 4:42 PM, Alexei Starovoitov <alexei.starovoi...@gmail.com> wrote: > On Tue, Nov 10, 2015 at 04:26:02PM -0800, Shi, Yang wrote: >> On 11/10/2015 4:08 PM, Eric Dumazet wrote: >> >On Tue, 2015-11-10 at 14:41 -0800, Yang Shi wrote: >> >>aarch64 doesn't have native support for XADD instruction, implement it by >> >>the below instruction sequence:
aarch64 supports atomic add in ARMv8.1. For ARMv8(.0), please consider using LDXR/STXR sequence. >> >> >> >>Load (dst + off) to a register >> >>Add src to it >> >>Store it back to (dst + off) >> > >> >Not really what is needed ? >> > >> >See this BPF_XADD as an atomic_add() equivalent. >> >> I see. Thanks. The documentation doesn't say too much about "exclusive" add. >> If so it should need load-acquire/store-release. > > I think doc is clear enough, but it can always be improved. Pls suggest a > patch. > It's quite hard to write a test for atomicity in test_bpf framework, so > code review is the key. Eric, thanks for catching it! > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
