Re: [9front] [PATCH] Unmount to remove sharp devices.

[Jacob Moody <moody@mail.posixcafe.org>]

On 5/4/22 19:59, Alex Musolino wrote:
> Did you consider implementing this with two commands (e.g.  'drop' and
> 'permit') on the /dev/drivers file itself?  That would make it just as
> easy to do this kind of stuff from a script/program without having to
> craft a namespace file.
> 
> Obviously you'd have to have the #c device available until you're
> finished "dropping" and "permitting" things, but perhaps that's not
> really a problem.

I think this is an excellent idea! The logic for doing permit within
the kernel is much easier, as we already have an array of all current
devices. I had started implementing a permit(1) and permit command for
namespace files and that necessitated reading /dev/drivers to get a
full list of current devices. While not a lot of code to do it, it
felt like I shouldn't have to do the inversion myself from userspace.

Unless others feel strongly about implementing device removal
through unmount I am going to plan to change the implementation
to do this instead.

Also from my understanding, dropping #c in practice shouldn't be
an issue, once you have a fd to #c/drivers, you can block #c and the fd
will still accept further writes. You may not be able to reopen
to #c/drivers file after closing that fd, but that seems completely
reasonable to me.

Thanks,
moody