From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756882AbZELG1p (ORCPT ); Tue, 12 May 2009 02:27:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753949AbZELG1f (ORCPT ); Tue, 12 May 2009 02:27:35 -0400 Received: from viefep20-int.chello.at ([62.179.121.40]:61191 "EHLO viefep20-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753897AbZELG1f (ORCPT ); Tue, 12 May 2009 02:27:35 -0400 X-SourceIP: 213.93.53.227 Subject: Re: [PATCH 3/5] perf_counter: rework ioctl()s From: Peter Zijlstra To: Paul Mackerras Cc: Arnd Bergmann , Ingo Molnar , Corey Ashford , linux-kernel@vger.kernel.org, Thomas Gleixner In-Reply-To: <18953.5533.398597.677737@drongo.ozlabs.ibm.com> References: <20090508165219.469818319@chello.nl> <20090508170028.837558214@chello.nl> <200905120158.46314.arnd@arndb.de> <1242108700.11251.304.camel@twins> <18953.5533.398597.677737@drongo.ozlabs.ibm.com> Content-Type: text/plain Date: Tue, 12 May 2009 08:27:30 +0200 Message-Id: <1242109650.11251.313.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2009-05-12 at 16:22 +1000, Paul Mackerras wrote: > Peter Zijlstra writes: > > > Hmm, are you saying that the 3rd argument to unlocked_ioctl is actually > > (void __user *) instead of unsigned long? > > He's saying (correctly) that using _IOR or _IOW implies that the ioctl > is going to read or write the memory location pointed to by the 3rd > argument to unlocked_ioctl. If the 3rd argument is just a number, not > an address, I believe you should use _IO. Oh, somewhat confusing all this. Would be good to spell out these things somewhere. Documentation/ioctl/ seems less than helpful.