Re: [PATCH 1/9] sysfs: add sysfs_remove_bin_file_self() function

[Zev Weiss]

On Wed, Oct 06, 2021 at 10:23:33PM PDT, Greg Kroah-Hartman wrote:
> On Wed, Oct 06, 2021 at 05:09:46PM -0700, Zev Weiss wrote:
> > This is simply the bin_attribute analog to sysfs_remove_file_self().
>
> No, no binary sysfs file should be triggering a remove.
>
> binary sysfs files are "pass-through-only" from userspace to hardware,
> the kernel should not be even knowing what is read/written to them.
>
> What do you think this is needed for?

So, I initially set out to be able to activate/deactivate specific DT 
nodes at runtime by using the device-tree "reserved" status as defined 
in the spec (but not currently used anywhere in the kernel) to mean 
essentially "create a device for this but don't bind a driver to it" 
(leaving it to userspace to invoke bind/unbind or similar), and added 
initial support for the specific driver I'm concerned with at the moment 
(aspeed-smc) -- that was the previous patch series linked in the cover 
letter of this one.

In the discussion of that series, Rob suggested as an alternate 
approach:

> Another possibility is making 'status' writeable from userspace. It is
> just a sysfs file.

That seemed sort of appealing to me, and this seemed like the most 
obvious way to go about implementing it.  Given that DT properties are 
binary attributes, I gather you'd consider that a non-starter though?


Zev