Re: [RFC][PATCH -mm take5 6/7] add ioctls for adding/removing target

From: Satyam Sharma
Date: Wed Jun 13 2007 - 16:41:39 EST

Hi Keiichi,

On 6/13/07, Keiichi KII <k-keiichi@xxxxxxxxxxxxx> wrote:
From: Keiichi KII <k-keiichi@xxxxxxxxxxxxx>

We add ioctls for adding/removing target.
we can dynamically add netconsole target.
we can dynamically remoe netconsole target.

*ugh*. I was wondering what a show-stopper this particular patch
was -- introduces a couple of ioctl()'s, exports a new structure to
userspace, adds a hitherto-unneeded header file, brings in
tty_struct/tty_operations and ends up adding so much complexity/
bloat to netconsole.c. Not only that, it must live together (and
side-by-side) with the sysfs interface also, because the two of them
do different things: sysfs to be able to modify target parameters at
run-time and the ioctl()'s to dynamically add/remove targets. We
can't really mkdir(2) or rmdir(2) in sysfs so the ioctl()'s are needed.

So may I suggest:

Just lose *both* the sysfs and ioctl() interfaces and use _configfs_.
It is *precisely* the thing you need in your driver here -- the ability
to create / destroy kernel objects (or config_items in configfs lingo)
from _userspace_ via simple mkdir(2) and rmdir(2). And configfs
makes changing multiple configurable parameters atomically trivial
too, via rename(2) ... not to mention a sysfs+ioctls -> configfs
conversion would help your patchset lose some weight too :-)

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