From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752887AbcBJPWt (ORCPT ); Wed, 10 Feb 2016 10:22:49 -0500 Received: from mout.kundenserver.de ([212.227.126.131]:61290 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364AbcBJPWp convert rfc822-to-8bit (ORCPT ); Wed, 10 Feb 2016 10:22:45 -0500 From: Arnd Bergmann To: Guenter Roeck Cc: linux-arm-kernel@lists.infradead.org, Greg Kroah-Hartman , Baruch Siach , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Jiri Slaby , kernel-testers@vger.kernel.org, Andrzej Hajda Subject: Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE Date: Wed, 10 Feb 2016 16:21:19 +0100 Message-ID: <2606061.l722KO95iI@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <56BAA27A.9050605@roeck-us.net> References: <1455030539-10798-1-git-send-email-linux@roeck-us.net> <4571887.rTPndCnv20@wuerfel> <56BAA27A.9050605@roeck-us.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="utf-8" X-Provags-ID: V03:K0:axG21r15CdDex3vu8x9TLIdyV/f6CTjpfpuxdRS+HYxKwEz39YD m01MEbHIrn5owB4AdvYxQ+vlJrVfWuQt1wWRc0CvByBCRTDZSutcr8vipdu4wbcAwFa6iQk h/on4LYNK80ia+pUcLStYQbSA3vC24YMIv00pOl12mOrI5qzi1g6FNwJ7uHs6iEAg60AlJb H4D0Q3bq3CPqtvgkoMeog== X-UI-Out-Filterresults: notjunk:1;V01:K0:PVSdCxHS/f4=:H0TWH8MipkVlgZ08gv9DME Ej+GMQYw0HsLPTvGIwcvA4vj7rKeUHqU0LNjKd9TjvIVftjDqqNPzoviVxsZJ3on2dc5sb2V+ JoQFgCDW22zuFbZM6bZWh0RSUsb7vyQkBnU83QlNY97rS0S1iCfiB/L6YRyRrhqdGO0aESxvN pEQ7zw+5sR9SWpzS12TVd7+YhrsPtauP4a1UdIK98DbpqIYZx4y9mMEHkuK6BRnAj1XNXfYPN 1SzL82R/RiAjK44StGtWsqqYhhuV7P279MswtOoqwZEsVfBo8FY9FgeKXXP7vAi28h7Q/YhkY MHdIQ7F7WETylW6US/8Vo6+Hvdsob/05OpD3ZDvsTqYI2DcAcNR5GFXBAOj+R5G+J018YE/Bo MitA6Uma0YgQl2fQUlw7Rh08d4z916ajUQ5KwJ75rSO+Xc1wdAj09V+CXnZWEJ328lbnGp7Pc y0JkzWL7/GWJFCSGNzZEsvmp3Gp4i8nClNHKLiKMvh/gxJJIW4gf8mtw1sBARV6/fsHho8j8n UxA7z7oYDd1K6UkFGPQ9XKZPHVf1EsqyxGN/sx/tQ/F9DSVyJQ2k7yblvp6CEJFv+nHd4VCoe 8Fw9Bxx2H8dGTZxGgKGZGfFjY8IbA+YZKNRsnXzi9dIEYa3FEKxDr+DDi2VgUKFWtZOzKJgwU IP84n0zyTOmoSexTT5/PoR4Uo3Iqq2wt+mYSDovUQjx/+TIJA7oKg+d48H1G2o6S2j1eYPyPa 49YG93BTTHbqxbUJ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 09 February 2016 18:37:46 Guenter Roeck wrote: > On 02/09/2016 07:26 AM, Arnd Bergmann wrote: > > On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote: > >> IS_ERR_VALUE() assumes that its parameter is an unsigned long. > >> It can not be used to check if an unsigned int reflects an error. > >> Doing so can result in the following build warning. > >> > >> drivers/tty/serial/digicolor-usart.c: In function ‘digicolor_uart_probe’: > >> include/linux/err.h:21:38: warning: > >> comparison is always false due to limited range of data type > >> drivers/tty/serial/digicolor-usart.c:485:6: note: > >> in expansion of macro ‘IS_ERR_VALUE’ > >> > >> If that warning is seen, an error return from platform_get_irq() is missed. > >> > >> > > > > The patch looks correct to me, but what compiler version and which kernel > > tree is it that triggered the warning? > > > > Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the > > changes are still under discussion, but I don't see that warning with > > any of the versions. > > > I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch. > > I agree that fixing the problem in IS_ERR_VALUE() is preferrable. > > Ah, W=1 explains it. We are still debating about the proper solution. Al Viro pointed out that most users of IS_ERR_VALUE() shouldn't be using it at all, so your patch is probably best here after all. Arnd