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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=unavailable 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 8BF60C38A2A for ; Fri, 8 May 2020 15:44:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7718721841 for ; Fri, 8 May 2020 15:44:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728237AbgEHPoz (ORCPT ); Fri, 8 May 2020 11:44:55 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2181 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727051AbgEHPoy (ORCPT ); Fri, 8 May 2020 11:44:54 -0400 Received: from lhreml710-chm.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id 80F5A89D46A181AD5269; Fri, 8 May 2020 16:44:53 +0100 (IST) Received: from localhost (10.47.95.97) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Fri, 8 May 2020 16:44:53 +0100 Date: Fri, 8 May 2020 16:44:30 +0100 From: Jonathan Cameron To: Alexandru Ardelean CC: , , Subject: Re: [PATCH 1/3] iio: core: wrap IIO device into a iio_dev_priv object Message-ID: <20200508164430.00001741@Huawei.com> In-Reply-To: <20200508164015.0000223f@Huawei.com> References: <20200508141306.17222-1-alexandru.ardelean@analog.com> <20200508164015.0000223f@Huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.95.97] X-ClientProxiedBy: lhreml743-chm.china.huawei.com (10.201.108.193) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 8 May 2020 16:40:15 +0100 Jonathan Cameron wrote: > On Fri, 8 May 2020 17:13:04 +0300 > Alexandru Ardelean wrote: > > > There are plenty of bad designs we want to discourage or not have to review > > manually usually about accessing private (marked as [INTERN]) fields of > > 'struct iio_dev'. > > This has been on the todo list for many years so great you are having a go. > > > > > This is difficult, as a lot of users copy drivers, and not always the best > > examples. > > > > A better idea is to hide those fields into the framework. > > For 'struct iio_dev' this is a 'struct iio_dev_priv' which wraps a public > > 'struct iio_dev' object. > > > > In the next patches, some fields will be moved to this new struct, each > > with it's own rework. > > > > This rework will not be complete[-able] for a while, as many fields need > > some drivers to be reworked in order to finalize them > > (e.g. 'indio_dev->mlock'). > > > > But some fields can already be moved, and in time, all of them may get > > there (in the 'struct iio_dev_priv' object). > > > > We also need to hide the implementations for 'iio_priv()' & > > 'iio_priv_to_dev()', as the pointer arithmetic will not match once things > > are moved. > > This last bit has the disadvantage of potentially putting a function > call in some fast paths where there wasn't one before. > > We may not need to 'forcefully' hide the internal parts. May be > enough to just make their use really obvious. If you have to cast > to an iio_dev_priv then you are doing something very wrong. Note, definitely keep the to_* macro only in the private core header. > The old stick __ in front of it may make that even more obvious. > > Naming is a bit confusing though. iio_dev_priv sounds like private > to the device... iio_dev_opaque maybe? > > > > > > Signed-off-by: Alexandru Ardelean > > --- > > > > Just as a note here, I've been running this patchset without a problem > > for 2 weeks now in a work branch. > > But it's only been a setup, so no idea if some other thing may cause > > bigger issues. > > > > This small patchset is meant to kickstart this, for GSoC people or for > > people wanting to start contributing to IIO. > > > > drivers/iio/iio_core.h | 11 +++++++++++ > > drivers/iio/industrialio-core.c | 32 +++++++++++++++++++++++++++----- > > include/linux/iio/iio.h | 12 ++---------- > > 3 files changed, 40 insertions(+), 15 deletions(-) > > > > diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h > > index fd9a5f1d5e51..84f3b4590c05 100644 > > --- a/drivers/iio/iio_core.h > > +++ b/drivers/iio/iio_core.h > > @@ -17,6 +17,17 @@ struct iio_dev; > > > > extern struct device_type iio_device_type; > > > > +/** > > + * struct iio_dev_priv - industrial I/O device private information > > + * @indio_dev: public IIO device object > > + */ > > +struct iio_dev_priv { > > + struct iio_dev indio_dev; > > +}; > > + > > +#define to_iio_dev_priv(indio_dev) \ > > + container_of(indio_dev, struct iio_dev_priv, indio_dev) > > + > > int __iio_add_chan_devattr(const char *postfix, > > struct iio_chan_spec const *chan, > > ssize_t (*func)(struct device *dev, > > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > > index 462d3e810013..f0888dd84d3d 100644 > > --- a/drivers/iio/industrialio-core.c > > +++ b/drivers/iio/industrialio-core.c > > @@ -164,6 +164,23 @@ static const char * const iio_chan_info_postfix[] = { > > [IIO_CHAN_INFO_THERMOCOUPLE_TYPE] = "thermocouple_type", > > }; > > > > + > > +void *iio_priv(const struct iio_dev *indio_dev) > > +{ > > + struct iio_dev_priv *iio_dev_priv = to_iio_dev_priv(indio_dev); > > + return (char *)iio_dev_priv + ALIGN(sizeof(struct iio_dev_priv), IIO_ALIGN); > > +} > > +EXPORT_SYMBOL_GPL(iio_priv); > > + > > +struct iio_dev *iio_priv_to_dev(void *priv) > > +{ > > + struct iio_dev_priv *iio_dev_priv = > > + (struct iio_dev_priv *)((char *)priv - > > + ALIGN(sizeof(struct iio_dev_priv), IIO_ALIGN)); > > + return &iio_dev_priv->indio_dev; > > +} > > +EXPORT_SYMBOL_GPL(iio_priv_to_dev); > > + > > /** > > * iio_find_channel_from_si() - get channel from its scan index > > * @indio_dev: device > > @@ -1476,6 +1493,8 @@ static void iio_device_unregister_sysfs(struct iio_dev *indio_dev) > > static void iio_dev_release(struct device *device) > > { > > struct iio_dev *indio_dev = dev_to_iio_dev(device); > > + struct iio_dev_priv *iio_dev_priv = to_iio_dev_priv(indio_dev); > > + > > if (indio_dev->modes & INDIO_ALL_TRIGGERED_MODES) > > iio_device_unregister_trigger_consumer(indio_dev); > > iio_device_unregister_eventset(indio_dev); > > @@ -1484,7 +1503,7 @@ static void iio_dev_release(struct device *device) > > iio_buffer_put(indio_dev->buffer); > > > > ida_simple_remove(&iio_ida, indio_dev->id); > > - kfree(indio_dev); > > + kfree(iio_dev_priv); > > } > > > > struct device_type iio_device_type = { > > @@ -1498,10 +1517,11 @@ struct device_type iio_device_type = { > > **/ > > struct iio_dev *iio_device_alloc(int sizeof_priv) > > { > > + struct iio_dev_priv *iio_dev_priv; > > struct iio_dev *dev; > > size_t alloc_size; > > > > - alloc_size = sizeof(struct iio_dev); > > + alloc_size = sizeof(struct iio_dev_priv); > > if (sizeof_priv) { > > alloc_size = ALIGN(alloc_size, IIO_ALIGN); > > alloc_size += sizeof_priv; > > @@ -1509,10 +1529,12 @@ struct iio_dev *iio_device_alloc(int sizeof_priv) > > /* ensure 32-byte alignment of whole construct ? */ > > alloc_size += IIO_ALIGN - 1; > > > > - dev = kzalloc(alloc_size, GFP_KERNEL); > > - if (!dev) > > + iio_dev_priv = kzalloc(alloc_size, GFP_KERNEL); > > + if (!iio_dev_priv) > > return NULL; > > > > + dev = &iio_dev_priv->indio_dev; > > + > > dev->dev.groups = dev->groups; > > dev->dev.type = &iio_device_type; > > dev->dev.bus = &iio_bus_type; > > @@ -1526,7 +1548,7 @@ struct iio_dev *iio_device_alloc(int sizeof_priv) > > if (dev->id < 0) { > > /* cannot use a dev_err as the name isn't available */ > > pr_err("failed to get device id\n"); > > - kfree(dev); > > + kfree(iio_dev_priv); > > return NULL; > > } > > dev_set_name(&dev->dev, "iio:device%d", dev->id); > > diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h > > index 5f9f439a4f01..38c4ea505394 100644 > > --- a/include/linux/iio/iio.h > > +++ b/include/linux/iio/iio.h > > @@ -678,16 +678,8 @@ static inline void *iio_device_get_drvdata(struct iio_dev *indio_dev) > > #define IIO_ALIGN L1_CACHE_BYTES > > struct iio_dev *iio_device_alloc(int sizeof_priv); > > > > -static inline void *iio_priv(const struct iio_dev *indio_dev) > > -{ > > - return (char *)indio_dev + ALIGN(sizeof(struct iio_dev), IIO_ALIGN); > > -} > > - > > -static inline struct iio_dev *iio_priv_to_dev(void *priv) > > -{ > > - return (struct iio_dev *)((char *)priv - > > - ALIGN(sizeof(struct iio_dev), IIO_ALIGN)); > > -} > > +void *iio_priv(const struct iio_dev *indio_dev); > > +struct iio_dev *iio_priv_to_dev(void *priv); > > > > void iio_device_free(struct iio_dev *indio_dev); > > struct iio_dev *devm_iio_device_alloc(struct device *dev, int sizeof_priv); > >