Re: SYSFS "errors"

Em Tue, 19 Feb 2013 13:35:02 +0100
Borislav Petkov [off-list ref] escreveu:

On Tue, Feb 19, 2013 at 09:16:10AM -0300, Mauro Carvalho Chehab wrote:

quoted

I'm not sure if is there a way to pass fs permissions to something similar
to device_create_file().

struct device_attribute.attr.mode? I.e., second arg.

Ah, now I see what you're meaning. That would require to dynamically
create a per-mci DEVICE_ATTR().

quoted

On both cases, an error will happen at open:
	- if file doesn't exist (this approach), it will return -ENOENT;
	- if file is opened with wrong permissions, open will return -EPERM.

However, if the file is not created, readdir() won't show the file.

Right, and in that case userspace which *assumes* it is always created -
like it is now - will fail when accessing it.

If simply you adjust the attributes accordingly but *always* create the
file and it has the correct permissions, everyone is happy. Right?

No, on both cases, open() will return an error (-ENOENT against -EPERM). 

If userspace doesn't check if open() failed, I can't see why
changing the open return error code would help.

-- 

Cheers,
Mauro