From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DFD1C3279B for ; Wed, 4 Jul 2018 10:11:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4EBA208B6 for ; Wed, 4 Jul 2018 10:11:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="RB+TWfvB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D4EBA208B6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753700AbeGDKLJ (ORCPT ); Wed, 4 Jul 2018 06:11:09 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:39058 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753295AbeGDKLG (ORCPT ); Wed, 4 Jul 2018 06:11:06 -0400 Received: by mail-wr0-f196.google.com with SMTP id b8-v6so4741621wro.6 for ; Wed, 04 Jul 2018 03:11:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=i2oGYEp341u8C1fswQNAfOIuZtruZ8UpU8iAoJupQ7M=; b=RB+TWfvBUGeLQzx8Vhkkm+7sqzmERHA/ekWJ1WdKmIJqE8I/MyCIOWe49OqFxIhLSW 7ACZAByXyPWgwg7GZVTZBj5w0Szbtca+wRwDiw/4sxoGXHEF/jtoy+2vYHgTdSVGTsJM NFW6xr7O1mvqlqt1Xr2r7hgVdkbuOoHfqXTFM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=i2oGYEp341u8C1fswQNAfOIuZtruZ8UpU8iAoJupQ7M=; b=GBoG31MqeVRLYeUab+9OJlAb72pyunejbEDp9nD0pYaNC21Rc6+ezQWynoNqGcLQ9m 44Zg3DF5y3FHC6pTxFrwUVSywJVxmjM5rxh6bLWc7d7gl1Op0VPnva2jz5/Uj1BQl2jw 3AuIso7aAwbaHnW//R4GJh8g5BXFsikmBr99q8Cgg+OzzKg9B9H9IeO1/wU6T7F0TgZv Cr2oIGw3p+UULA5Z0/V93+ZJMCfjXd+d9VhByEprkLs4VNctlzn9F4aMHKNMyJM2INO5 xv83n26jD3C01V+G2VoHEPzoSzuiokkpNJaJbTTJmZ8t1yA1EAk0H7YWD4NHTlIp3XI6 KjWw== X-Gm-Message-State: APt69E11MOZq4BYVaXANsxpLOPBKgBGiNUy1V3i8mjbv12sqm1nQO/fP 08p++iWZwMU89X5TnKAuWUCCwg== X-Google-Smtp-Source: AAOMgpdCOu8dQkAQFVBozBfBD3H9O+NTufg5q6gAhoHNRmc1q6HOdr/pyF1Sewa0Ohjr7WbVNR1qGg== X-Received: by 2002:adf:b05c:: with SMTP id g28-v6mr1112784wra.128.1530699064938; Wed, 04 Jul 2018 03:11:04 -0700 (PDT) Received: from dell ([2.27.167.87]) by smtp.gmail.com with ESMTPSA id o8-v6sm6489881wro.68.2018.07.04.03.11.03 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 04 Jul 2018 03:11:04 -0700 (PDT) Date: Wed, 4 Jul 2018 11:11:02 +0100 From: Lee Jones To: Matti Vaittinen Cc: Enric Balletbo Serra , Michael Turquette , Rob Herring , Mark Rutland , Liam Girdwood , Mark Brown , Matti Vaittinen , Arnd Bergmann , Dmitry Torokhov , Sebastian Reichel , chenjh@rock-chips.com, Andrey Smirnov , Linus Walleij , Kate Stewart , Heiko =?iso-8859-1?Q?St=FCbner?= , Greg Kroah-Hartman , sboyd@kernel.org, linux-clk@vger.kernel.org, "devicetree@vger.kernel.org" , linux-kernel , linux-input@vger.kernel.org, mikko.mutanen@fi.rohmeurope.com, heikki.haikola@fi.rohmeurope.com Subject: Re: [PATCH v8 1/2] mfd: bd71837: mfd driver for ROHM BD71837 PMIC Message-ID: <20180704101102.GA496@dell> References: <18a04e42debb2a23aec855cac3bcf3d6ab6c55fd.1530259815.git.matti.vaittinen@fi.rohmeurope.com> <20180704083911.GH2118@localhost.localdomain> <20180704095257.GJ2118@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180704095257.GJ2118@localhost.localdomain> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 04 Jul 2018, Matti Vaittinen wrote: > On Wed, Jul 04, 2018 at 11:39:11AM +0300, Matti Vaittinen wrote: > > On Tue, Jul 03, 2018 at 11:26:00AM +0200, Enric Balletbo Serra wrote: > > > Missatge de Matti Vaittinen del > > > dia dv., 29 de juny 2018 a les 11:47: > > > > > > Now that you use devm calls and you don't need to unwind things I > > > think is better to use plain returns. So, > > > > > > return -ENOMEM; > > > > I have never really understood why use of gotos in error handling is > > discouraged. They're not. > > Personally I would always choose single point of exit from > > a function when it is simple enough to achieve (like in this case). I've > > written and fixed way too many functions which leak resources or > > accidentally keep a lock when exiting from error branches. But I know > > many colleagues like you who prefer not to have gotos but in place returns > > instead. So I guess I'll leave the final call on this to the one who is > > maintainer for this code. And it is true there is no things to unwind > > now - which does not mean that next updater won't add such. But as I > > said, I know plenty of people share your view - and even though I rather > > maintain code with only one exit the final call is on subsystem maintainer > > here. Please use gotos in the error path. IMO, it's the nicest way to unwind (as you call it). > Actually, If it was completely my call the probe would look something > like this: > > +static int bd71837_i2c_probe(struct i2c_client *i2c, > + const struct i2c_device_id *id) > +{ > + struct bd71837 *bd71837; > + struct bd71837_board *board_info; > + int gpio_intr = 0; > + > + const char *errstr = "No IRQ configured"; > + int ret = -EINVAL; > + > + bd71837 = devm_kzalloc(&i2c->dev, sizeof(struct bd71837), GFP_KERNEL); > + > + if (bd71837 == NULL) > + return -ENOMEM; > + > + board_info = dev_get_platdata(&i2c->dev); > + > + if (!board_info) > + gpio_intr = i2c->irq; > + else > + gpio_intr = board_info->gpio_intr; > + > + if (!gpio_intr) > + goto err_out; > + > + i2c_set_clientdata(i2c, bd71837); > + bd71837->dev = &i2c->dev; > + bd71837->i2c_client = i2c; > + bd71837->chip_irq = gpio_intr; > + > + errstr = "regmap initialization failed"; > + > + bd71837->regmap = devm_regmap_init_i2c(i2c, &bd71837_regmap_config); > + ret = PTR_ERR(bd71837->regmap); > + if (IS_ERR(bd71837->regmap)) > + goto err_out; > + > + errstr = "Read BD71837_REG_DEVICE failed"; > + ret = bd71837_reg_read(bd71837, BD71837_REG_REV); > + if (ret < 0) > + goto err_out; > + > + errstr = "Failed to add irq_chip"; > + ret = devm_regmap_add_irq_chip(&i2c->dev, bd71837->regmap, > + bd71837->chip_irq, IRQF_ONESHOT, 0, > + &bd71837_irq_chip, &bd71837->irq_data); > + if (ret < 0) > + goto err_out; > + > + errstr = "Failed to configure button short press timeout"; > + ret = regmap_update_bits(bd71837->regmap, > + BD71837_REG_PWRONCONFIG0, > + BD718XX_PWRBTN_PRESS_DURATION_MASK, > + BD718XX_PWRBTN_SHORT_PRESS_10MS); > + if (ret < 0) > + goto err_out; > + > + /* According to BD71847 datasheet the HW default for long press > + * detection is 10ms. So lets change it to 10 sec so we can actually > + * get the short push and allow gracefull shut down > + */ > + ret = regmap_update_bits(bd71837->regmap, > + BD71837_REG_PWRONCONFIG1, > + BD718XX_PWRBTN_PRESS_DURATION_MASK, > + BD718XX_PWRBTN_LONG_PRESS_10S); > + > + errstr = "Failed to configure button long press timeout"; > + if (ret < 0) > + goto err_out; > + > + btns[0].irq = regmap_irq_get_virq(bd71837->irq_data, > + BD71837_INT_PWRBTN_S); > + > + errstr = "Failed to get the IRQ"; > + ret = btns[0].irq; > + if (btns[0].irq < 0) > + goto err_out; > + > + errstr = "Failed to create subdevices"; > + ret = devm_mfd_add_devices(bd71837->dev, PLATFORM_DEVID_AUTO, > + bd71837_mfd_cells, > + ARRAY_SIZE(bd71837_mfd_cells), NULL, 0, > + regmap_irq_get_domain(bd71837->irq_data)); > + if (ret) { > +err_out: > + if (errstr) > + dev_err(&i2c->dev, "%s (%d)\n", errstr, ret); > + } > + > + return ret; > +} > > What do you think of this? To my eye it is nice. It keeps single point of > exit and introduces only simple if-statements without the need of curly > brackets. And finally the error prints string works as a comment too. > I've seen bunch of constructs like this on the networking side but I > have no idea if this is frowned on this subsystem =) Oh, and probe abowe > is just to illustrate the idea, I did not even try compiling it yet. That is horrible. I nearly vomited on my keyboard. It doesn't flow anywhere nearly as nicely has sorting out all of the error handling *after* it has been detected. You're sacrificing readability to save a single line and do not save any *actual* lines of code, only a brace. Landing a goto in the middle of a statement is messy and unsightly. What happens when you have some resources to free? The last few lines will become very messy, very quickly. Nit: "something == NULL" is better written as "!something". Nit: Please use proper multi-line comments as per the Coding Style. -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog