linux-kernel - Re: [PATCH] UIO: introduce sysfs_ops for map_attr

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Date:	Tue, 19 Feb 2008 13:12:01 +0100
From:	Hans-Jürgen Koch <hjk@...utronix.de>
To:	Brandon Philips <brandon@...p.org>
Cc:	Greg KH <greg@...ah.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] UIO: introduce sysfs_ops for map_attr_ktype

Am Tue, 19 Feb 2008 01:55:05 -0800
schrieb Brandon Philips <brandon@...p.org>:

> This fixes two bugs with UIO that cropped up recently in -rc1
> 
> 1) WARNING: at fs/sysfs/file.c:334 sysfs_open_file when trying to open
>    a map addr/size file - complaining about missing sysfs_ops for
> ktype 
> 2) Permission denied when reading uio/uio0/maps/map0/{addr,size} when
>    files are mode S_IRUGO
> 
> Also fix a typo: attr_attribute -> addr_attribute

Hi Brandon,
thanks a lot for that one! I've tested with 2.6.25-rc2 with a Hilscher
NetX PCI card, works without problems. All attributes are accessible.
Makes 2.6.25-rc usable again :-)

Thanks,
Hans

> 
> Signed-off-by: Brandon Philips <bphilips@...e.de>

Signed-off-by: Hans J. Koch <hjk@...utronix.de>


> 
> ---
>  drivers/uio/uio.c          |   54
> ++++++++++++++++++++++++++++++--------------- 1 file changed, 37
> insertions(+), 17 deletions(-)
> 
> Index: linux-2.6/drivers/uio/uio.c
> ===================================================================
> --- linux-2.6.orig/drivers/uio/uio.c
> +++ linux-2.6/drivers/uio/uio.c
> @@ -57,29 +57,29 @@ struct uio_map {
>  };
>  #define to_map(map) container_of(map, struct uio_map, kobj)
>  
> -
> -static ssize_t map_attr_show(struct kobject *kobj, struct
> kobj_attribute *attr,
> -			     char *buf)
> +static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
>  {
> -	struct uio_map *map = to_map(kobj);
> -	struct uio_mem *mem = map->mem;
> -
> -	if (strncmp(attr->attr.name, "addr", 4) == 0)
> -		return sprintf(buf, "0x%lx\n", mem->addr);
> -
> -	if (strncmp(attr->attr.name, "size", 4) == 0)
> -		return sprintf(buf, "0x%lx\n", mem->size);
> +	return sprintf(buf, "0x%lx\n", mem->addr);
> +}
>  
> -	return -ENODEV;
> +static ssize_t map_size_show(struct uio_mem *mem, char *buf)
> +{
> +	return sprintf(buf, "0x%lx\n", mem->size);
>  }
>  
> -static struct kobj_attribute attr_attribute =
> -	__ATTR(addr, S_IRUGO, map_attr_show, NULL);
> -static struct kobj_attribute size_attribute =
> -	__ATTR(size, S_IRUGO, map_attr_show, NULL);
> +struct uio_sysfs_entry {
> +	struct attribute attr;
> +	ssize_t (*show)(struct uio_mem *, char *);
> +	ssize_t (*store)(struct uio_mem *, const char *, size_t);
> +};
> +
> +static struct uio_sysfs_entry addr_attribute =
> +	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
> +static struct uio_sysfs_entry size_attribute =
> +	__ATTR(size, S_IRUGO, map_size_show, NULL);
>  
>  static struct attribute *attrs[] = {
> -	&attr_attribute.attr,
> +	&addr_attribute.attr,
>  	&size_attribute.attr,
>  	NULL,	/* need to NULL terminate the list of
> attributes */ };
> @@ -90,8 +90,28 @@ static void map_release(struct kobject *
>  	kfree(map);
>  }
>  
> +static ssize_t map_type_show(struct kobject *kobj, struct attribute
> *attr,
> +			     char *buf)
> +{
> +	struct uio_map *map = to_map(kobj);
> +	struct uio_mem *mem = map->mem;
> +	struct uio_sysfs_entry *entry;
> +
> +	entry = container_of(attr, struct uio_sysfs_entry, attr);
> +
> +	if (!entry->show)
> +		return -EIO;
> +
> +	return entry->show(mem, buf);
> +}
> +
> +static struct sysfs_ops uio_sysfs_ops = {
> +	.show = map_type_show,
> +};
> +
>  static struct kobj_type map_attr_type = {
>  	.release	= map_release,
> +	.sysfs_ops	= &uio_sysfs_ops,
>  	.default_attrs	= attrs,
>  };
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