Re: 2.6.35-rc2 module reference counting broken

From: Tejun Heo
Date: Thu Jun 10 2010 - 07:31:50 EST


Hello,

On 06/10/2010 08:34 AM, Jari Ruusu wrote:
> Later in the mount system call handling the module refrence count is
> incremented. But to me that looks like there is a window of opportunity for
> things to go wrong. What is there to prevent module from being removed at
> zero refcount?

It can be removed, in which case blkdev_get() fails and the whole open
attempt fails, which is the expected behavior. Claiming block just
needs access to the containing struct block_device, caring for the
actual device and backing module is blkdev_get()'s job.

Thanks.

--
tejun
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