From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933584AbcA0Wru (ORCPT ); Wed, 27 Jan 2016 17:47:50 -0500 Received: from mail.efficios.com ([78.47.125.74]:52029 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754046AbcA0Wrr (ORCPT ); Wed, 27 Jan 2016 17:47:47 -0500 Date: Wed, 27 Jan 2016 22:47:37 +0000 (UTC) From: Mathieu Desnoyers To: Josh Triplett Cc: Thomas Gleixner , Paul Turner , Andrew Hunter , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-api , Andy Lutomirski , Andi Kleen , Dave Watson , Chris Lameter , Ingo Molnar , Ben Maurer , rostedt , "Paul E. McKenney" , Linus Torvalds , Andrew Morton , Russell King , Catalin Marinas , Will Deacon , Michael Kerrisk Message-ID: <75735238.6347.1453934857246.JavaMail.zimbra@efficios.com> In-Reply-To: <20160127221142.GA8935@cloud> References: <1453913683-28915-1-git-send-email-mathieu.desnoyers@efficios.com> <1453913683-28915-2-git-send-email-mathieu.desnoyers@efficios.com> <671969438.6129.1453915918933.JavaMail.zimbra@efficios.com> <974364259.6329.1453930475174.JavaMail.zimbra@efficios.com> <20160127221142.GA8935@cloud> Subject: Re: [RFC PATCH v2 1/3] getcpu_cache system call: cache CPU number of running thread MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [78.47.125.74] X-Mailer: Zimbra 8.6.0_GA_1178 (ZimbraWebClient - FF43 (Linux)/8.6.0_GA_1178) Thread-Topic: getcpu_cache system call: cache CPU number of running thread Thread-Index: aUYKZiGjhDI466OH+T/WtNWAAAD6fg== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Jan 27, 2016, at 5:11 PM, Josh Triplett josh@joshtriplett.org wrote: > On Wed, Jan 27, 2016 at 09:34:35PM +0000, Mathieu Desnoyers wrote: >> ----- On Jan 27, 2016, at 12:37 PM, Thomas Gleixner tglx@linutronix.de wrote: >> >> > On Wed, 27 Jan 2016, Thomas Gleixner wrote: >> > >> >> On Wed, 27 Jan 2016, Mathieu Desnoyers wrote: >> >> > ----- On Jan 27, 2016, at 12:22 PM, Thomas Gleixner tglx@linutronix.de wrote: >> >> > Sounds fair. What is the recommended typing for "ptr" then ? >> >> > uint32_t ** or uint32_t * ? >> >> > >> >> > It would be expected to pass a "uint32_t *" for the set >> >> > operation, but the "get" operation requires a "uint32_t **". >> >> >> >> Well, you can't change the types depending on the opcode, so you need to stick >> >> with **. >> > >> > Alternatively you make it: >> > >> > (opcode, *newptr, **oldptr, flags); >> >> I'm tempted to stick to (opcode, **ptr, flags), because >> other syscalls that have "*newptr", "**oldptr" >> typically have them because they save the current state >> into oldptr, and set the new state, which is really >> not the case here. To eliminate any risk of confusion, >> I am tempted to keep a single "**ptr". >> >> Unless someone has a better idea... > > Either that or you could define it as "void *" and interpret it based on > flags, but that seems unfortunate; let's not imitate ioctl-style > typeless parameters. I'd stick with the double pointer and the current > behavior. Allright, will do! Thanks for the feedback :) Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com