From 69e2387f3bfd408c7fb6c0d14b83d792f67ed638 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@mev.co.uk>
Date: Fri, 8 Nov 2013 15:03:39 +0000
Subject: [PATCH] staging: comedi: kcomedilib: protect against device
 detachment

The functions in "kcomedilib" need to prevent the comedi device being
detached during their operation.  This can be done by acquiring either
the main mutex or the "attach lock" semaphore in the `struct
comedi_device`.  Use the attach lock when merely checking whether the
device is attached.  Use the mutex when processing a comedi instruction.

Also, don't bother trying to manipulate the module use count of
low-level comedi driver in `comedi_open()` and `comedi_close()`.  If the
device gets detached while it is "open", we wouldn't be able to
decrement the module use count anyway.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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