Messages in this thread Patch in this message | | | Date | Wed, 28 May 2014 01:43:44 -0700 | From | Brian Norris <> | Subject | Re: [PATCH 01/27] mtd: nand: introduce function to fix a common bug in most nand-drivers not showing a device in sysfs |
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On Tue, May 27, 2014 at 12:12:26AM +0200, Alexander Holler wrote: > --- a/include/linux/mtd/mtd.h > +++ b/include/linux/mtd/mtd.h > @@ -23,7 +23,7 @@ > #include <linux/types.h> > #include <linux/uio.h> > #include <linux/notifier.h> > -#include <linux/device.h> > +#include <linux/platform_device.h> > > #include <mtd/mtd-abi.h> > > @@ -366,6 +366,15 @@ static inline int mtd_can_have_bb(const struct mtd_info *mtd) > struct mtd_partition; > struct mtd_part_parser_data; > > +static inline void mtd_setup_common_members(struct mtd_info *mtd, void *priv, > + struct platform_device *pdev)
Thanks for the diligence on catching these issues, but I'm not sure this helper function is fully the correct approach here.
> +{ > + mtd->priv = priv;
I don't think you should hide this one here. It will be quite obvious if a driver didn't stash its private data but tries to access it later. Are there any drivers that missed this?
> + mtd->owner = pdev->dev.driver->owner; > + mtd->dev.parent = &pdev->dev; > + mtd->name = pdev->dev.driver->name;
I think this is a little dangerous. You're potentially clobbering the name that a driver already chose here. And why did you pick to use the driver name? This gives non-unique names if there is more than one device instantiated for a driver. That's why some drivers already use the device name, not the driver name:
mtd->name = dev_name(&pev->dev);
And in fact, if any drivers are missing mtd->name, perhaps it's best to just modify the MTD registration to give them a default:
if (!mtd->name) mtd->name = dev_name(&pdev->dev);
> +}
BTW, nothing in this function actually makes sense to require a platform_device, does it? And it's possible to have non-platform drivers that want to do basic MTD initialization. So (if we still keep this helper function at all), I'd recommend just a 'struct device *dev' parameter.
> + > extern int mtd_device_parse_register(struct mtd_info *mtd, > const char * const *part_probe_types, > struct mtd_part_parser_data *parser_data,
How about we rethink the "helper" approach, and instead just do validation in the core code? This would cover most of the important parts of your helper, I think:
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index d201feeb3ca6..39ba5812a5a3 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -397,6 +397,11 @@ int add_mtd_device(struct mtd_info *mtd) if (device_register(&mtd->dev) != 0) goto fail_added; + if (mtd->dev.parent) + mtd->owner = mtd->dev.parent->driver->owner; + else + WARN_ON(1); + if (MTD_DEVT(i)) device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c index 1ca9aec141ff..9869bbef50cf 100644 --- a/drivers/mtd/mtdpart.c +++ b/drivers/mtd/mtdpart.c @@ -370,7 +370,6 @@ static struct mtd_part *allocate_partition(struct mtd_info *master, slave->mtd.subpage_sft = master->subpage_sft; slave->mtd.name = name; - slave->mtd.owner = master->owner; slave->mtd.backing_dev_info = master->backing_dev_info; /* NOTE: we don't arrange MTDs as a tree; it'd be error-prone -- Brian
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