/etc/hotplug or /etc/hotplug.d ?

/etc/hotplug or /etc/hotplug.d ?

[martin f krafft]

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Hi folks,

I develop the user-space driver for a USB device (libphidgets). To
be able to make it as easy as possible to my users, I want to
register a hotplug hook that chmod's the /proc/bus/usb/*/* file to
0660:root:phidgets upon connection, so that (only) members of the
phidgets group can use it.

There seem to be two approaches.

At first, I was using a simple script in /etc/hotplug/usb:

  http://cvs.ailab.ch/cgi-bin/viewcvs.cgi/external/libphidgets/hotplug/Attic/phidgets?rev=1.2&view=auto

along with a user map entry to have the script called upon insertion
of a USB device with a certain ID pair:

  http://cvs.ailab.ch/cgi-bin/viewcvs.cgi/external/libphidgets/hotplug/Attic/phidgets.usermap?rev=1.2&view=auto

Greg KH suggested to me not to bother with the usermaps and instead
provide a script in /etc/hotplug.d/usb instead. So I did:

  http://cvs.ailab.ch/cgi-bin/viewcvs.cgi/external/libphidgets/hotplug/phidgets.hotplug?rev=1.3&view=auto

Both approaches work. However, now I am being told that it is
"better" to use /etc/hotplug (like I did in the first approach).
I was unable to squeeze any real arguments out of the person
asserting this.

But it got me thinking, so I want to find the real answer now.

Using /etc/hotplug.d/usb seems to have the advantage that it does
not need the usermap, but it's called for every USB device ever
inserted.

/etc/hotplug/usb is only called if the usermap line matches. It
requires the line to specify a script to be called. However, scripts
are also called upon loading of a module by the same name by
hotplug, so there is a potential source of conflict.

What's your opinion? Which hook should I prefer?

Thanks,

-- 
martin;              (greetings from the heart of the sun.)
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Re: /etc/hotplug or /etc/hotplug.d ?

[Greg KH]

On Sat, Feb 12, 2005 at 05:35:24PM +0100, martin f krafft wrote:
> Hi folks,
> 
> I develop the user-space driver for a USB device (libphidgets). To
> be able to make it as easy as possible to my users, I want to
> register a hotplug hook that chmod's the /proc/bus/usb/*/* file to
> 0660:root:phidgets upon connection, so that (only) members of the
> phidgets group can use it.
> 
> There seem to be two approaches.
> 
> At first, I was using a simple script in /etc/hotplug/usb:
> 
>   http://cvs.ailab.ch/cgi-bin/viewcvs.cgi/external/libphidgets/hotplug/Attic/phidgets?rev=1.2&view=auto
> 
> along with a user map entry to have the script called upon insertion
> of a USB device with a certain ID pair:
> 
>   http://cvs.ailab.ch/cgi-bin/viewcvs.cgi/external/libphidgets/hotplug/Attic/phidgets.usermap?rev=1.2&view=auto
> 
> Greg KH suggested to me not to bother with the usermaps and instead
> provide a script in /etc/hotplug.d/usb instead. So I did:
> 
>   http://cvs.ailab.ch/cgi-bin/viewcvs.cgi/external/libphidgets/hotplug/phidgets.hotplug?rev=1.3&view=auto
> 
> Both approaches work. However, now I am being told that it is
> "better" to use /etc/hotplug (like I did in the first approach).
> I was unable to squeeze any real arguments out of the person
> asserting this.

Who said to do it that way?

> But it got me thinking, so I want to find the real answer now.
> 
> Using /etc/hotplug.d/usb seems to have the advantage that it does
> not need the usermap, but it's called for every USB device ever
> inserted.

True.  But a simple check at the start of your script/program will
handle that properly, right?

> /etc/hotplug/usb is only called if the usermap line matches. It
> requires the line to specify a script to be called. However, scripts
> are also called upon loading of a module by the same name by
> hotplug, so there is a potential source of conflict.

True, stay away from this, people are working to get rid of the
/etc/hotplug/ scripts :)

> What's your opinion? Which hook should I prefer?

Again, what's the problem with using /etc/hotplug.d/ ?

thanks,

greg k-h


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Re: /etc/hotplug or /etc/hotplug.d ?

[martin f krafft]

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also sprach Greg KH <greg@kroah.com> [2005.02.15.0831 +0100]:
> True, stay away from this, people are working to get rid of the
> /etc/hotplug/ scripts :)

Thanks, this is the argument I was looking for.

-- 
martin;              (greetings from the heart of the sun.)
  \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck
 
invalid/expired pgp subkeys? use subkeys.pgp.net as keyserver!
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linux: because a pc is a terrible thing to waste

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