RE: [PATCH] sysfs: Allow bin_attributes to be added to groups

[Dan Williams <dan.j.williams@intel.com>]

Lukas Wunner wrote:
> Commit dfa87c824a9a ("sysfs: allow attributes to be added to groups")
> introduced dynamic addition of sysfs attributes to groups.
> 
> Allow the same for bin_attributes, in support of a forthcoming commit
> which adds various bin_attributes every time a PCI device is
> authenticated.
> 
> Addition of bin_attributes to groups differs from regular attributes in
> that different kernfs_ops are selected by sysfs_add_bin_file_mode_ns()
> vis-à-vis sysfs_add_file_mode_ns().
> 
> So call either of those two functions from sysfs_add_file_to_group()
> based on an additional boolean parameter and add two wrapper functions,
> one for bin_attributes and another for regular attributes.
> 
> Removal of bin_attributes from groups does not require a differentiation
> for bin_attributes and can use the same code path as regular attributes.
> 
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: Alan Stern <stern@rowland.harvard.edu>
> ---
> Submitting this ahead of my PCI device authentication v2 patches.
> Not sure if the patch is acceptable without an accompanying user,
> but even if it's not, perhaps someone has early review feedback
> or wants to provide an Acked-by?  Thank you!

On the one hand it makes sense from a symmetry perspective, on the other
hand the expectation and the infrastructure for dynamic sysfs visibilty
has increased since 2007.

That is why I would like to see the use case to understand why a
dynamically added a bin_attribute is needed compared with a statically
defined attribute with dynamic visibility.