From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751533AbcBLGkF (ORCPT ); Fri, 12 Feb 2016 01:40:05 -0500 Received: from mailout2.w1.samsung.com ([210.118.77.12]:42797 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750823AbcBLGkA (ORCPT ); Fri, 12 Feb 2016 01:40:00 -0500 MIME-version: 1.0 Content-type: text/plain; charset=utf-8 X-AuditID: cbfec7f4-f79026d00000418a-1e-56bd7e3de379 Content-transfer-encoding: 8BIT Subject: Re: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE To: Guenter Roeck References: <1455030539-10798-1-git-send-email-linux@roeck-us.net> <4571887.rTPndCnv20@wuerfel> <56BAA27A.9050605@roeck-us.net> <2606061.l722KO95iI@wuerfel> <56BC022B.7030004@roeck-us.net> <56BC2DF7.20803@samsung.com> <20160211153243.GA3076@roeck-us.net> Cc: Arnd Bergmann , 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 From: Andrzej Hajda Message-id: <56BD7DFB.10608@samsung.com> Date: Fri, 12 Feb 2016 07:38:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 In-reply-to: <20160211153243.GA3076@roeck-us.net> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrNLMWRmVeSWpSXmKPExsVy+t/xq7q2dXvDDG5O5bb4O+kYu8WKa29Y LJoXr2ezmLLhA5PFv7YeZotNj6+xWlzeNYfN4sziXnaLJwvPMDlwevz+NYnRY//cNewem5fU e+z83sDusX7LVRaPuQ23mDw+b5ILYI/isklJzcksSy3St0vgyuiZs56xYLd0xbtZv5gbGFeL dTFyckgImEj8eDmVHcIWk7hwbz1bFyMXh5DAUkaJW1deM4EkeAUEJX5MvsfSxcjBwSwgL3Hk UjaEqS4xZUouRPlzRolpZ38wgpQLC3hKbJ1/DqxVREBNovlUC9TMFiaJj/NfsoI4zAJzmCSu bbjFClLFJqAp8XfzTTaIZRoSM5bNYwTZwCKgKvGz1QUkLCoQIXG4s4sdJMwpYChx/rP9BEaB WUium4Vw3SyE6xYwMq9iFE0tTS4oTkrPNdQrTswtLs1L10vOz93ECImCLzsYFx+zOsQowMGo xMNrcGtPmBBrYllxZe4hRgkOZiURXgmuvWFCvCmJlVWpRfnxRaU5qcWHGKU5WJTEeefueh8i JJCeWJKanZpakFoEk2Xi4JRqYBRQPPOxx2fmrePcFQuW/o7R4AmSK1s4iVl5ncIC2Rc/XKVO ztibKsUV9Z1z2iflFddjS1oqG1OS80WOr1t06bbpKfMdIZWvLt7uu/6T7Yeaa+h9D5Eo7bB9 9cpJCXNWi7MwaCYIzvCYcN7H1vvT3x+71/btW/pnbn9CpeAhf7bau/9kO8/VNyixFGckGmox FxUnAgCFyU/tfgIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/11/2016 04:32 PM, Guenter Roeck wrote: > On Thu, Feb 11, 2016 at 07:45:11AM +0100, Andrzej Hajda wrote: >> On 02/11/2016 04:38 AM, Guenter Roeck wrote: >>> On 02/10/2016 07:21 AM, Arnd Bergmann wrote: >>>> 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. >>>> >>> Yes, after looking into it some more I agree. Coccinelle should be able to handle >>> most of the conversions automatically. I actually tried to write a script, just >>> for the fun of it, but it misses some of the problem cases in patch mode. >>> Maybe I get it working tonight. >>> >>> Guenter >>> >> Maybe it can be helpful. The script which classifies all IS_ERR_VALUE >> usages as >> correct, signed, incorrect and unknown (cocci was not able to detect type). >> Adding patch mode should be quite simple. >> >> // Options: --all-includes --include >> include/uapi/linux/netfilter_ipv6/ip6_tables.h --include >> include/uapi/linux/netfilter_ipv4/ip_tables.h --include >> include/uapi/linux/netfilter_arp/arp_tables.h --include >> include/uapi/linux/netfilter/x_tables.h --include include/linux/mm_types.h >> >> virtual context >> virtual report >> >> @r@ >> typedef bool, u8, u16, u32, u64, s8, s16, s32, s64, __u64, dma_addr_t, >> Elf32_Addr, Elf64_Addr; >> {unsigned long, size_t} ev; >> {short, int, long, s16, s32, ssize_t} ew; >> {char, unsigned char, unsigned short, unsigned int, long long, unsigned >> long long, bool, u8, u16, u32, u64, s64, __u64, dma_addr_t, Elf32_Addr, >> Elf64_Addr} ei; >> expression eu; >> position p; >> @@ >> >> IS_ERR_VALUE(\(ev \| ew \| ei \| eu \))@p >> >> @script:python depends on report@ >> p << r.p = []; >> ev << r.ev = ""; >> ew << r.ew = ""; >> ei << r.ei = ""; >> eu << r.eu = ""; > This doesn't work for me; it bails out at the assignments. If I remove > the assignments, it does not report anything. > > Any idea what might be wrong ? Old version of spatch. Default values are supported since 1.0.3. Regards Andrzej