From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Schwab Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures Date: Wed, 02 Mar 2016 10:28:40 +0100 Message-ID: References: <1456851608-3374907-1-git-send-email-arnd@arndb.de> <1456851608-3374907-2-git-send-email-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100") Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Geert Uytterhoeven Cc: Arnd Bergmann , Alexandre Belloni , "linux-arm-kernel@lists.infradead.org" , Kyle McMartin , RTCLINUX , Alessandro Zummo , "linuxppc-dev@lists.ozlabs.org" , Linux-sh list , Parisc List , linux-m68k , "linux-kernel@vger.kernel.org" Geert Uytterhoeven writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Schwab Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures Date: Wed, 02 Mar 2016 10:28:40 +0100 Message-ID: References: <1456851608-3374907-1-git-send-email-arnd@arndb.de> <1456851608-3374907-2-git-send-email-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain Cc: Arnd Bergmann , Alexandre Belloni , "linux-arm-kernel\@lists.infradead.org" , Kyle McMartin , RTCLINUX , Alessandro Zummo , "linuxppc-dev\@lists.ozlabs.org" , Linux-sh list , Parisc List , linux-m68k , "linux-kernel\@vger.kernel.org" To: Geert Uytterhoeven Return-path: In-Reply-To: (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100") List-ID: List-Id: linux-parisc.vger.kernel.org Geert Uytterhoeven writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out.m-online.net (mail-out.m-online.net. [212.18.0.9]) by gmr-mx.google.com with ESMTPS id 71si23870wmp.0.2016.03.02.01.28.49 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 02 Mar 2016 01:28:49 -0800 (PST) From: Andreas Schwab To: Geert Uytterhoeven Cc: Arnd Bergmann , Alexandre Belloni , "linux-arm-kernel\@lists.infradead.org" , Kyle McMartin , RTCLINUX , Alessandro Zummo , "linuxppc-dev\@lists.ozlabs.org" , Linux-sh list , Parisc List , linux-m68k , "linux-kernel\@vger.kernel.org" Subject: [rtc-linux] Re: [PATCH 1/6] rtc: generic: allow building on all architectures References: <1456851608-3374907-1-git-send-email-arnd@arndb.de> <1456851608-3374907-2-git-send-email-arnd@arndb.de> Date: Wed, 02 Mar 2016 10:28:40 +0100 In-Reply-To: (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Reply-To: rtc-linux@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , Geert Uytterhoeven writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." -- -- You received this message because you are subscribed to "rtc-linux". Membership options at http://groups.google.com/group/rtc-linux . Please read http://groups.google.com/group/rtc-linux/web/checklist before submitting a driver. --- You received this message because you are subscribed to the Google Groups "rtc-linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/d/optout. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Schwab Date: Wed, 02 Mar 2016 09:28:40 +0000 Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures Message-Id: List-Id: References: <1456851608-3374907-1-git-send-email-arnd@arndb.de> <1456851608-3374907-2-git-send-email-arnd@arndb.de> In-Reply-To: (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100") MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org Geert Uytterhoeven writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." From mboxrd@z Thu Jan 1 00:00:00 1970 From: schwab@linux-m68k.org (Andreas Schwab) Date: Wed, 02 Mar 2016 10:28:40 +0100 Subject: [PATCH 1/6] rtc: generic: allow building on all architectures In-Reply-To: (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100") References: <1456851608-3374907-1-git-send-email-arnd@arndb.de> <1456851608-3374907-2-git-send-email-arnd@arndb.de> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Geert Uytterhoeven writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas. -- Andreas Schwab, schwab at linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754655AbcCBJ2z (ORCPT ); Wed, 2 Mar 2016 04:28:55 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:46883 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754213AbcCBJ2w (ORCPT ); Wed, 2 Mar 2016 04:28:52 -0500 X-Auth-Info: LKwvR4beBDtCEnmhJ3r230jK3TPBnpoDNEwCaJoBOju3UScgo8Ad68OBH+UEEw8o From: Andreas Schwab To: Geert Uytterhoeven Cc: Arnd Bergmann , Alexandre Belloni , "linux-arm-kernel\@lists.infradead.org" , Kyle McMartin , RTCLINUX , Alessandro Zummo , "linuxppc-dev\@lists.ozlabs.org" , Linux-sh list , Parisc List , linux-m68k , "linux-kernel\@vger.kernel.org" Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures References: <1456851608-3374907-1-git-send-email-arnd@arndb.de> <1456851608-3374907-2-git-send-email-arnd@arndb.de> X-Yow: Okay.. I'm going home to write the ``I HATE RUBIK's CUBE HANDBOOK FOR DEAD CAT LOVERS''.. Date: Wed, 02 Mar 2016 10:28:40 +0100 In-Reply-To: (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Geert Uytterhoeven writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."