On Thu, 3 Dec 2020 10:35:50 -0600 George Prekas <preka...@amazon.com> wrote:
> On 12/3/2020 10:08 AM, Stephen Hemminger wrote: > > On Thu, 3 Dec 2020 07:59:54 -0600 > > George Prekas <preka...@amazon.com> wrote: > > > >> Insert a compiler barrier to make sure that the IP checksum calculation > >> happens after setting all the fields of the IP header. > >> > >> Signed-off-by: George Prekas <preka...@amazon.com> > > I don't think this is necessary. All other OS's don't have to do this. > > The CPU is going to maintain proper memory order. > > Hi Stephen, > > This is not a CPU or OS issue. This is a compiler issue. The compiler is > free to reorder statements if it does not detect dependencies between > them. Without this compiler barrier, the calculated IP checksum is wrong. > > But the compiler should be detecting any aliasing here, if no you have a bad compiler.
