Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270032AbTGLXsN (ORCPT ); Sat, 12 Jul 2003 19:48:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270034AbTGLXsN (ORCPT ); Sat, 12 Jul 2003 19:48:13 -0400 Received: from x35.xmailserver.org ([208.129.208.51]:56463 "EHLO x35.xmailserver.org") by vger.kernel.org with ESMTP id S270032AbTGLXsK (ORCPT ); Sat, 12 Jul 2003 19:48:10 -0400 X-AuthUser: davidel@xmailserver.org Date: Sat, 12 Jul 2003 16:55:10 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@bigblue.dev.mcafeelabs.com To: Eric Varsanyi cc: Linux Kernel Mailing List Subject: Re: [Patch][RFC] epoll and half closed TCP connections In-Reply-To: <20030712231147.GI15643@srv.foo21.com> Message-ID: References: <20030712181654.GB15643@srv.foo21.com> <20030712194432.GE10450@mail.jlokier.co.uk> <20030712205114.GC15643@srv.foo21.com> <20030712211941.GD15643@srv.foo21.com> <20030712231147.GI15643@srv.foo21.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1341 Lines: 42 On Sat, 12 Jul 2003, Eric Varsanyi wrote: > > (Sorry, I missed this) > > You can work that out very easily. When your read/write returns a lower > > number of bytes, it means that it is time to stop processing this fd. If > > events happened meanwhile, you will get them at the next epoll_wait(). If > > not, the next time they'll happen. There's no blind spot if you follow > > this simple rule, and you do not even have the extra syscall with EAGAIN. > > The scenario that I think is still uncovered (edge trigger only): > > User Kernel > -------- ---------- > Read data added to socket > > Socket posts read event to epfd > > epoll_wait() Event cleared from epfd, EPOLLIN > returned to user > > more read data added to socket > > Socket posts a new read event to epfd > > read() until short read with EAGAIN all data read from socket > > epoll_wait() returns another EPOLLIN for socket and > clears it from epfd > > read(), returns 0 right away socket buffer is empty read will return -1 with errno=EAGAIN in that case, not zero. - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/