Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753094AbaBYKaR (ORCPT ); Tue, 25 Feb 2014 05:30:17 -0500 Received: from dcvr.yhbt.net ([64.71.152.64]:58650 "EHLO dcvr.yhbt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750770AbaBYKaO (ORCPT ); Tue, 25 Feb 2014 05:30:14 -0500 Date: Tue, 25 Feb 2014 10:30:14 +0000 From: Eric Wong To: Nathaniel Yazdani Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH for-next 2/4] epoll: epoll() syscall declaration Message-ID: <20140225103013.GB9963@dcvr.yhbt.net> References: <1393206162-18151-1-git-send-email-n1ght.4nd.d4y@gmail.com> <1393206162-18151-3-git-send-email-n1ght.4nd.d4y@gmail.com> <20140224053232.GB7056@dcvr.yhbt.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Nathaniel Yazdani wrote: > On Sun, Feb 23, 2014 at 9:32 PM, Eric Wong wrote: > > Nathaniel Yazdani wrote: > >> +asmlinkage long sys_epoll(int ep, struct epoll __user *in, > >> + unsigned int inc, struct epoll __user *out, > >> + unsigned int outc, int timeout); > > > > I can understand using the new struct for 'in', but 'out' could just be > > "struct epoll_event *" like sys_epoll_wait, right? > > > >> asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events, > > Yeah and I went back and forth on that, it just seemed to me that the > inconsistency could be confusing to others... maybe instead of defining a new > struct to begin with it might make me sense to just have an 'infd' array of file > descriptors in addition to an 'in' array of epoll_event struct > (obviously the length > of these would be identical). I don't think a separate array for in is a good idea, too error prone and you lose locality. For output, some users either end up allocating more memory/retrieve fewer items with the larger struct for *out. -- 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/