From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D36A1C432C0 for ; Mon, 2 Dec 2019 08:47:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A647821774 for ; Mon, 2 Dec 2019 08:47:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pGVkQKfZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726473AbfLBIrz (ORCPT ); Mon, 2 Dec 2019 03:47:55 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:51657 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725977AbfLBIrz (ORCPT ); Mon, 2 Dec 2019 03:47:55 -0500 Received: by mail-wm1-f68.google.com with SMTP id g206so20807562wme.1; Mon, 02 Dec 2019 00:47:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=zyOKweXKHOPtqk+48O/QHHMQCCOb/ibIpSzxHuzne4E=; b=pGVkQKfZstToZiwqGP39z4Wy9KIhn5MnEXy6JSxCglui3LGSJZ/unwHs3izmEj0w9u LHVsZCJH9ZQ+CIsdzkZ1m38wwkYKx560rta1CAzquV/qW7IdGvyLG6W9jEABLuF+zpqy 3eQ6+hbSW0uLQVb351xC6/IiXlFMFOQW8sMpToM1i7JiN8wpTxabXrr/cFgtQxjjUaz4 P0ijV+6XFt3Vy5QFrrXPXLNhO//G1kYDPEP8czX4NmVCBPi61hBeSBQIctjM2TS15fCP k3VPMklRw6PnpedXaiNk/WDHFfG8sWzf3BCdE+M3MIEYlcfVPQATaP0yT31WWwDQVdFz O6Bg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=zyOKweXKHOPtqk+48O/QHHMQCCOb/ibIpSzxHuzne4E=; b=kW9dHI+gty4Znzz/HcgYS14ejbStwPal+S8MFbD7NdWB5YzsGYMVCRDzQQGTZMgUks 5EhaTPXrDbSuCqCcJdbNz/BkjUFi8GLEusVr+z4lMDuXrNljI7jLei3ACY2NAPd3wrjd yyBFtPIf56GhDC9eoccC3IrSVPbXgT3a97jFoMSut4dGm62W7yA86227ZD/0a+VforQz ZED3JJLyk5faW3yW0j9pBlR/J5kMLKLTgELJHkHarh14aacWdEORXnoxnIVhVn5UGoTD /G4hq+6H3gzRKuukzgjbFXY2LDu3lDfJTKS3afqOBS7WZm9xycX+EgFqg6DivN0kTsN6 U+Og== X-Gm-Message-State: APjAAAWjB3wISBYomwT+rJfyZsvRrfIRKUgalvF8CpgjgvRFcRkXxpR6 GjykQzDeLwE2mDVpaYgPC/o= X-Google-Smtp-Source: APXvYqz5uCyAD5CSXVQpElDuIk/VKSs+/hEVEVHXQgAf1sWm3bXsklsVGYc8ngStuhcDka3q39loqQ== X-Received: by 2002:a1c:6707:: with SMTP id b7mr23290086wmc.54.1575276473006; Mon, 02 Dec 2019 00:47:53 -0800 (PST) Received: from pali ([2a02:2b88:2:1::5cc6:2f]) by smtp.gmail.com with ESMTPSA id h124sm23837188wme.30.2019.12.02.00.47.51 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 02 Dec 2019 00:47:52 -0800 (PST) Date: Mon, 2 Dec 2019 09:47:50 +0100 From: Pali =?utf-8?B?Um9ow6Fy?= To: Dmitry Torokhov Cc: Abhishek Pandit-Subedi , linux-input@vger.kernel.org, linux-bluetooth@vger.kernel.org, Luiz Augusto von Dentz , Enric Balletbo i Serra , linux-kernel@vger.kernel.org, Thomas Gleixner , Logan Gunthorpe , Andrey Smirnov , Kirill Smelkov Subject: Re: [PATCH] Input: uinput - Add UI_SET_UNIQ ioctl handler Message-ID: <20191202084750.k7lafzzrf3yq2tqs@pali> References: <20191127185139.65048-1-abhishekpandit@chromium.org> <20191201145357.ybq5gfty4ulnfasq@pali> <20191202012305.GQ248138@dtor-ws> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191202012305.GQ248138@dtor-ws> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 01 December 2019 17:23:05 Dmitry Torokhov wrote: > Hi Pali, > > On Sun, Dec 01, 2019 at 03:53:57PM +0100, Pali Rohár wrote: > > Hello! > > > > On Wednesday 27 November 2019 10:51:39 Abhishek Pandit-Subedi wrote: > > > Support setting the uniq attribute of the input device. The uniq > > > attribute is used as a unique identifier for the connected device. > > > > > > For example, uinput devices created by BlueZ will store the address of > > > the connected device as the uniq property. > > > > > > Signed-off-by: Abhishek Pandit-Subedi > > > > ... > > > > > diff --git a/include/uapi/linux/uinput.h b/include/uapi/linux/uinput.h > > > index c9e677e3af1d..d5b7767c1b02 100644 > > > --- a/include/uapi/linux/uinput.h > > > +++ b/include/uapi/linux/uinput.h > > > @@ -145,6 +145,7 @@ struct uinput_abs_setup { > > > #define UI_SET_PHYS _IOW(UINPUT_IOCTL_BASE, 108, char*) > > > #define UI_SET_SWBIT _IOW(UINPUT_IOCTL_BASE, 109, int) > > > #define UI_SET_PROPBIT _IOW(UINPUT_IOCTL_BASE, 110, int) > > > +#define UI_SET_UNIQ _IOW(UINPUT_IOCTL_BASE, 111, char*) > > > > I think that usage of char* as type in _IOW would cause compatibility > > problems like it is for UI_SET_PHYS (there is UI_SET_PHYS_COMPAT). Size > > of char* pointer depends on userspace (32 vs 64bit), so 32bit process on > > 64bit kernel would not be able to call this new UI_SET_UNIQ ioctl. > > > > I would suggest to define this ioctl as e.g.: > > > > #define UI_SET_UNIQ _IOW(_IOC_WRITE, UINPUT_IOCTL_BASE, 111, 0) > > > > And then in uinput.c code handle it as: > > > > case UI_SET_UNIQ & ~IOCSIZE_MASK: > > > > as part of section /* Now check variable-length commands */ > > If we did not have UI_SET_PHYS in its current form, I'd agree with you, > but I think there is benefit in having UI_SET_UNIQ be similar to > UI_SET_PHYS. I thought that ioctl is just number, so we can define it as we want. And because uinput.c has already switch for variable-length commands it would be easy to use it. Final handling can be in separate function like for UI_SET_PHYS which can look like same. > But you are absolutely correct that in current form the patch is > deficient on 64/32 systems, and the compat handling needs to be added > before it can be accepted. Is not better to avoid usage of compat ioctl? Or it is OK to use compat ioctl also for new features? I do not know if there are some kernel rules for it or not... But for me it sounds like "compatibility layer for older code". -- Pali Rohár pali.rohar@gmail.com