On Fri 2019-09-20 00:02:55, Greg Kroah-Hartman wrote: > From: Willem de Bruijn <will...@google.com> > > [ Upstream commit acdcecc61285faed359f1a3568c32089cc3a8329 ] > > UDP reuseport groups can hold a mix unconnected and connected sockets. > Ensure that connections only receive all traffic to their 4-tuple. > > Fast reuseport returns on the first reuseport match on the assumption > that all matches are equal. Only if connections are present, return to > the previous behavior of scoring all sockets. > > Record if connections are present and if so (1) treat such connected > sockets as an independent match from the group, (2) only return > 2-tuple matches from reuseport and (3) do not return on the first > 2-tuple reuseport match to allow for a higher scoring match later. > > New field has_conns is set without locks. No other fields in the > bitmap are modified at runtime and the field is only ever set > unconditionally, so an RMW cannot miss a change.
That's an ... extremely tricky game with concurrent access. I'm pretty sure it is not valid C, but maybe it is acceptable for kernel. > --- a/include/net/sock_reuseport.h > +++ b/include/net/sock_reuseport.h > @@ -21,7 +21,8 @@ struct sock_reuseport { > unsigned int synq_overflow_ts; > /* ID stays the same even after the size of socks[] grows. */ > unsigned int reuseport_id; > - bool bind_inany; > + unsigned int bind_inany:1; > + unsigned int has_conns:1; But should it at least be commented here? If someone adds another int :1, he may get a surprise... Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
signature.asc
Description: Digital signature