Johannes Erdfelt writes:
> On an unrelated point, I have a question about changing permissions and
> supression.
>
> I have a module which dynamically tracks permissions for USB devices
> and applies them back to the device when it gets plugged back in.
>
> In the REGISTER handler, I do a chown/chmod pair (well, fchown/fchmod)
> which then generates another CHANGE request, causing extra processing since
> it looks like a user (admin, etc) made a change to file, when it was
> actually generated by devfsd.
>
> Would it be possible for devfs (the kernel portion) to not generate
> events when the devfsd process (or the process which has .devfsd
> open) makes changes?
This is possible, but it has a performance impact, since inode changes
will then require a test to see if the changing process is devfsd or
one of its children. This involves walking up the process tables.
And even if it were free, there's still a problem:
> I can't see a reason where it would be needed since devfsd is always
> aware of the changes it makes, since it made them in the first
> place.
That's only really true for devfsd itself. It doesn't know what
dynamically loaded extensions or scripts will do.
Regards,
Richard....
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