From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH] i2c: allow building emev2 without slave mode again Date: Mon, 14 Dec 2015 23:27:22 +0100 Message-ID: <13702087.6o87OAVdIx@wuerfel> References: <201512102224.cVm7Hcp0%fengguang.wu@intel.com> <15285750.UWXWiNJ6YU@wuerfel> <20151214135206.GA1520@katana> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from mout.kundenserver.de ([217.72.192.74]:63259 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753567AbbLNW2B (ORCPT ); Mon, 14 Dec 2015 17:28:01 -0500 In-Reply-To: <20151214135206.GA1520@katana> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Wolfram Sang Cc: kbuild test robot , kbuild-all@01.org, linux-i2c@vger.kernel.org, Niklas =?ISO-8859-1?Q?S=F6derlund?= , linux-sh@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org On Monday 14 December 2015 14:52:06 Wolfram Sang wrote: > > > What about not ifdeffing the inline function and keep the build error > > > whenever someone uses it without I2C_SLAVE being selected? > > > > The inline function is only added there for the case that I2C_SLAVE is > > disabled, so that would be pointless. > > > > However, what we could do is move the extern declaration outside of > > the #ifdef to make it always visible. The if(IS_ENABLED(CONFIG_I2C_SLAVE)) > > check should then ensure that it never actually gets called, and we > > get a link error if some driver gets it wrong. > > Yes, that's what I meant: move the whole function (as it was before your > patch) out of the CONFIG_I2C_SLAVE block. We should get a compiler error > even, because for !I2C_SLAVE, the client struct will not have the > slave_cb member. > But we don't want a compile-error for randconfig builds, and we don't want unnecessary #ifdef in the driver. This change on top of my earlier patch should do what I meant: diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 0236e5f2b5be..536641bad92d 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -265,15 +265,15 @@ enum i2c_slave_event { extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb); extern int i2c_slave_unregister(struct i2c_client *client); +#if IS_ENABLED(CONFIG_I2C_SLAVE) static inline int i2c_slave_event(struct i2c_client *client, enum i2c_slave_event event, u8 *val) { -#if IS_ENABLED(CONFIG_I2C_SLAVE) return client->slave_cb(client, event, val); +} #else - return 0; +extern int i2c_slave_event(struct i2c_client *client, enum i2c_slave_event event, u8 *val); #endif -} /** * struct i2c_board_info - template for device creation Arnd