try_module_get question

try_module_get question

[Robert Beckett]

Hi all,

Im a newcomer to kernel development, and have my first question :

I want to create a small module that simply powers on an FPGA, and 
powers it off when it is released. Two other modules will then depend on 
this module and control different devices programmed into the FPGA. So 
that the shared module does not get removed before any of the device 
drivers, I want to do a try_module_get from each driver targeting the 
shared module. What is the easiest way to get a reference to the shared 
module?

My current thought is to export a function that will return a reference 
to it (using THIS_MODULE from the shared module). The device driver 
modules can then try_module_get the returned module. Is this the best 
way to do this?

Is there an alternative way? maybe based on a similar system to the 
device / driver matching code?
There seem to be a lot of FAQs online saying that you need to get and 
put a module before calling any function that may stall for example, but 
they dont tell you how to get the module reference to use.

Or am I just missing something obvious?

Thanks

Robert Beckett.

Re: try_module_get question

[Jan Engelhardt]

On Jul 16 2007 14:22, Robert Beckett wrote:
> Hi all,
>
> Im a newcomer to kernel development, and have my first question :
>
> I want to create a small module that simply powers on an FPGA, and powers it
> off when it is released. Two other modules will then depend on this module and
> control different devices programmed into the FPGA.

How do they depend on it?

> So that the shared module
> does not get removed before any of the device drivers, I want to do a
> try_module_get from each driver targeting the shared module. What is the
> easiest way to get a reference to the shared module?
>
> My current thought is to export a function that will return a reference to it
> (using THIS_MODULE from the shared module). The device driver modules can then
> try_module_get the returned module. Is this the best way to do this?
>
> Is there an alternative way? maybe based on a similar system to the device /
> driver matching code?
> There seem to be a lot of FAQs online saying that you need to get and put a
> module before calling any function that may stall for example, but they dont
> tell you how to get the module reference to use.
>
> Or am I just missing something obvious?
>
> Thanks
>
> Robert Beckett.

	Jan
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