[linux-dvb] Re: [PATCH] Lock adapter modules when devices areopen

[Jon Burgess <mplayer@jburgess.uklinux.net>]

Johannes Stezenbach wrote:


> I just gave it a try with 2.4 and it didn't work. I was able
> to unload dvb-ttpci while szap was running, resulting in an
> Oops when I interrupted szap.
I did testing on both 2.4 and 2.6 with two budget Nova-T cards. I'm sure 
I tried doing the same thing with tzap and it worked OK.

I assume that when you did the test you did remove and reload all the 
dvb modules, including dvb-core?

The locking is done by the try_module_get() in the generic dvb-core 
open() file operation, so I don't see how it can not get called when the 
device node gets opened. A couple of printk's should show whether the 
code gets run and whether the module pointer is set to something valid.
Perhaps adding a debug print of the module name would be appropriate.

The other possibility is that is locking the wrong module.

It looks like the dvb-ttpci module statically links the av7110 code, 
which should provide the correct module reference when it calls 
dvb_register_adapter().

The budget driver is divided into a common budget-core module and a card 
specific budget driver. It is the budget-core which does the 
dvb_register_adapter() call, but the budget driver which needs to get 
locked. I have to pass the module pointer from the budget driver to the 
budget-core.

	Jon






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