linux-kernel - Reference counting of MMC host driver modules

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Date:	Fri, 09 Jan 2009 18:07:15 +0100
From:	Enrik Berkhan <Enrik.Berkhan@...com>
To:	Pierre Ossman <drzeus-mmc@...eus.cx>
CC:	linux-kernel@...r.kernel.org
Subject: Reference counting of MMC host driver modules

Hi,

I've noticed recently that the MMC/SD block driver does not reference 
count the MMC/SD host driver module that it uses via the MMC/SD core 
layer. Thus, I can rmmod my host driver module while, for example, a 
partition on a SD card is mounted.

Assuming this does not happen intentionally, what would be the correct 
fix? Is a try_module_get(card->host->parent->driver->owner) in 
mmc_blk_alloc() in drivers/mmc/card/block.c the right thing to do? If 
so, I could provide a patch fixing the issue. If not, please give me 
advice how to do it better :) (May be I'm missing something that has to 
do with hotplugging, as the devices I'm using are non-removeable).

Or am I possibly doing something wrong in my host driver and this 
problem is not present for others at all?

Enrik
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