UIO sysfs attributes broken in 2.6.25-rc1

UIO sysfs attributes broken in 2.6.25-rc1

[Hans-Jürgen Koch]

In 2.6.25-rc1, there's a strange effect:
Although the map attributes "addr" and "size" show up correctly:

-r--r--r-- 1 root root 4096 2008-02-13 17:49 addr
-r--r--r-- 1 root root 4096 2008-02-13 17:49 size

you cannot access them, not even as root. Something like "cat addr"
fails with a no-permission-error. It works fine in 2.6.24-rc8.

This is probably related to this patch:

http://lkml.org/lkml/2008/1/25/149

Unfortunately, I signed-off that one, too... I checked if all sysfs
files appear, but didn't try to access them. Sorry.

Greg, any ideas?

Thanks,
Hans

Re: UIO sysfs attributes broken in 2.6.25-rc1

[Greg KH]

On Wed, Feb 13, 2008 at 06:03:04PM +0100, Hans-J??rgen Koch wrote:
> In 2.6.25-rc1, there's a strange effect:
> Although the map attributes "addr" and "size" show up correctly:
> 
> -r--r--r-- 1 root root 4096 2008-02-13 17:49 addr
> -r--r--r-- 1 root root 4096 2008-02-13 17:49 size
> 
> you cannot access them, not even as root. Something like "cat addr"
> fails with a no-permission-error. It works fine in 2.6.24-rc8.
> 
> This is probably related to this patch:
> 
> http://lkml.org/lkml/2008/1/25/149
> 
> Unfortunately, I signed-off that one, too... I checked if all sysfs
> files appear, but didn't try to access them. Sorry.

Heh, well at least it wasn't just me that thought the patch was correct
:)

> Greg, any ideas?

I'll look into it this afternoon...

thanks,

greg k-h

[PATCH] UIO: introduce sysfs_ops for map_attr_ktype

[Brandon Philips]

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

Signed-off-by: Brandon Philips <bphilips@suse.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,
 };

Re: [PATCH] UIO: introduce sysfs_ops for map_attr_ktype

[Hans-Jürgen Koch]

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

Signed-off-by: Hans J. Koch <hjk@linutronix.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,
>  };

Re: [PATCH] UIO: introduce sysfs_ops for map_attr_ktype

[Greg KH]

On Tue, Feb 19, 2008 at 01:55:05AM -0800, Brandon Philips wrote:
> 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
> 
> Signed-off-by: Brandon Philips <bphilips@suse.de>

Hm, I thought I could get away with just using a kobject attribute, not
a special one.

Thanks for fixing this, it was my fault.

greg k-h