From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQmCV-00083R-H1 for barebox@lists.infradead.org; Fri, 09 Oct 2020 06:48:24 +0000 Date: Fri, 9 Oct 2020 08:48:20 +0200 From: Sascha Hauer Message-ID: <20201009064820.GT11648@pengutronix.de> References: <20201007095058.22950-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201007095058.22950-1-a.fatoum@pengutronix.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH v2 1/7] driver: introduce less error-prone dev_get_drvdata alternative To: Ahmad Fatoum Cc: barebox@lists.infradead.org On Wed, Oct 07, 2020 at 11:50:52AM +0200, Ahmad Fatoum wrote: > We use dev_get_drvdata to get the driver match data associated with a > device. This has two shortcomings: > > - Linux has dev_get_drvdata too, which returns a private pointer for > driver specific info to associate with a device. We use dev->priv > (or more often container_of) for that in barebox instead > > - It nearly always involves a cast to a double pointer, which is > error-prone as size and alignment match need to be ensured > on the programmer's part and can easily be gotten wrong: > enum dev_type type; > dev_get_drvdata(dev, (const void **)&type); // UB! > > Add a new function that instead of using a double pointer argument, > returns the pointer directly: > > - For normal pointer driver data, no cast is necessary > - For integer driver data casted to a pointer for storage, > the cast is still necessary, but it's only a single pointer > this way > > Signed-off-by: Ahmad Fatoum Applied, thanks Sascha > --- > v1 -> v2: > - Changed second patch to use pointer instead of enum in match data > (Sascha) > - Changed third and fourth patch to return error on match with > driver name instead of assuming to be compatible with a default > type. > --- > drivers/base/driver.c | 11 +++++++++++ > include/driver.h | 18 ++++++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/drivers/base/driver.c b/drivers/base/driver.c > index 412db6c40699..3205bbc3c33b 100644 > --- a/drivers/base/driver.c > +++ b/drivers/base/driver.c > @@ -500,3 +500,14 @@ int dev_get_drvdata(struct device_d *dev, const void **data) > > return -ENODEV; > } > + > +const void *device_get_match_data(struct device_d *dev) > +{ > + if (dev->of_id_entry) > + return dev->of_id_entry->data; > + > + if (dev->id_entry) > + return (void *)dev->id_entry->driver_data; > + > + return NULL; > +} > diff --git a/include/driver.h b/include/driver.h > index 1961ab6ed9ea..e2886d051d4f 100644 > --- a/include/driver.h > +++ b/include/driver.h > @@ -540,8 +540,26 @@ int devfs_create_partitions(const char *devname, > #define DRV_OF_COMPAT(compat) \ > IS_ENABLED(CONFIG_OFDEVICE) ? (compat) : NULL > > +/** > + * dev_get_drvdata - get driver match data associated with device > + * @dev: device instance > + * @data: pointer to void *, where match data is stored > + * > + * Returns 0 on success and error code otherwise. > + * > + * DEPRECATED: use device_get_match_data instead, which avoids > + * common pitfalls due to explicit pointer casts > + */ > int dev_get_drvdata(struct device_d *dev, const void **data); > > +/** > + * device_get_match_data - get driver match data associated with device > + * @dev: device instance > + * > + * Returns match data on success and NULL otherwise > + */ > +const void *device_get_match_data(struct device_d *dev); > + > int device_match_of_modalias(struct device_d *dev, struct driver_d *drv); > > #endif /* DRIVER_H */ > -- > 2.28.0 > > > _______________________________________________ > barebox mailing list > barebox@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/barebox > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox