[PATCH] was: mdev doesn't remove devices

[Rob Landley]

On Monday 28 August 2006 5:21 pm, Jason Schoon wrote:
> Since we're on the topic of mdev already, I have a patch I had to create
> today that I thought I would run by the list.
> 
> I am using mdev with a mdev.conf to launch a script file in certain cases
> (basically it enables hotplugging on USB flash devices for me).
> 
> In that script, I happened to add a line that sends its output to /dev/null
> (i.e. 2>/dev/null).  Well, this just so happens to create an empty file,
> which then causes mknod of /dev/null to fail with an "already exists."

You're calling this from a hotplug script that's called before /dev/null 
exists.  This really sounds like pilot error to me.

> So, my solution was to either make sure that my hotplug script never, ever
> talks to a dev file (a poor assumption I feel),

You're creating your devices via hotplug and you want to assume that random 
devices have already been created?

> or to patch mdev to check if 
> something is a regular file, and delete it.  Attached is a patch that
> accomplishes just that.  If someone else thinks that is a sane thing to do,
> please apply.

Isn't this really a special case for /dev/null?  Why not mknod /dev/null from 
your init script if your hotplug scripts are going to assume it exists before 
the hotplug scripts have been called?

If you don't want to build in mknod, you can get mdev to do it:

  ACTION=add DEVPATH=/sys/class/mem/null mdev

Rob
-- 
Never bet against the cheap plastic solution.