Re: introduce device_is_attached()

[Paul Goyette <paul%whooppee.com@localhost>]

Along these same lines, it might be nice if there were a way to 
determine if _any_ instances of a device were attached.  This is 
particularly useful for device-driver modules, which should prevent 
themselves from being unloaded if there are active instances.

A quick check of some device-driver modules show that they simply call 
config_fini_component() which updates autoconfig tables, but doesn't 
seem to check if a driver instance exists...




On Mon, 16 Apr 2012, Christoph Egger wrote:

> Hi,
>
> I want to introduce a new function to sys/devices.h:
>
> bool device_is_attached(device_t parent, cfdata_t cf);
>
> The purpose is for bus drivers who wants to attach children
> and ensure that only one instance of it will attach.
>
> 'parent' is the bus driver and 'cf' is the child device
> as passed to the submatch callback via config_search_loc().
>
> The return value is true if the child is already attached.
>
> I implemented a reference usage of it in amdnb_misc.c to ensure
> that amdtemp only attaches once on rescan.
>
> Any comments to the patch?
>
> Christoph
>
>
> !DSPAM:4f8c4e7e1986566716057!

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