[PATCH 0/3] sysfs: Refine is_visible API

From: Guenter Roeck
Date: Mon Jan 19 2015 - 16:43:54 EST


Up to now, is_visible can only be used to either remove visibility
of a file entirely or to add permissions, but not to reduce permissions.
This makes it impossible, for example, to use DEVICE_ATTR_RW to define
file attributes and reduce permissions to read-only.

This behavior is undesirable and unnecessarily complicates code which
needs to reduce permissions; instead of just returning the desired
permissions, it has to ensure that the permissions in the attribute
variable declaration only reflect the minimal permissions ever needed.

Change semantics of is_visible to only use the permissions returned
from it instead of oring the returned value with the hard-coded
permissions.

The code now dumps a warning to the console if an is_visible function
returns unexpected permissions.

Also document struct attribute_group.

Tested with v3.19-rc5.
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