From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann 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> 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: QUOTED-PRINTABLE Return-path: In-Reply-To: <56BAA27A.9050605-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="utf-8" To: Guenter Roeck Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Greg Kroah-Hartman , Baruch Siach , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jiri Slaby , kernel-testers-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrzej Hajda 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 =E2=80=98digicol= or_uart_probe=E2=80=99: > >> include/linux/err.h:21:38: warning: > >> comparison is always false due to limited range of data t= ype > >> drivers/tty/serial/digicolor-usart.c:485:6: note: > >> in expansion of macro =E2=80=98IS_ERR_VALUE=E2=80=99 > >> > >> If that warning is seen, an error return from platform_get_irq() i= s 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 t= he > > changes are still under discussion, but I don't see that warning wi= th > > any of the versions. > > > I see it with gcc 5.1 and 5.2 (and W=3D1). I did not see / notice And= rzej's patch. >=20 > I agree that fixing the problem in IS_ERR_VALUE() is preferrable. >=20 >=20 Ah, W=3D1 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