From: Evgeniy Polyakov <[EMAIL PROTECTED]> Date: Fri, 16 Feb 2007 21:34:27 +0300
> Otherwise we can extend select output mask to include hungup too > (getting into account that hungup is actually output event). POLLHUP is non-maskable and this is very clearly defined in just about every Unix definition of poll(). This non-maskability leads to all the strange semantics in this area. There is simply no way for sockets to return HUP for someone who is only waiting to write. Definitions of POLLHUP include language such as "This event and POLLOUT are mutually exclusive". I reviewed the current code and the many (and I mean MANY) threads on this topic that have occurred over the years going back to even 1999, and what we're doing now is the best possible set of semantics we can provide without breaking any existing applications. How many others have gone into the archives and actually looked at the discussions? That appears to be going out of style :-/ Now, on the read side, for the epoll folks, we added a POLLRDHUP to handle that case. It's not relevant here, but I'm mentioning it in passing since it's roughly related and it shows part of the devil in dealing with POLLHUP semantics. POLLHUP is a complete mess, because it means different things on different kinds of fds. And exactly, because it is not maskable, this makes it totally useless for sockets. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
