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Date: Wed, 27 Apr 2011 15:35:25 +0200
From: Bartosz Fabianowski <freebsd@chillt.de>
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Cc: freebsd-hackers@freebsd.org, Hans Petter Selasky <hselasky@c2i.net>
Subject: Re: Is there some implicit locking of device methods?
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> The global kind of last close is communicated to cdev by calling cdevsw
> close method. It is known to be not quite reliable, and esp. hard in
> relation to the forced unmounts of devfs mount points.
>
> The close of file (when no other file descriptors referencing the file are
> left) ends in cdevpriv destructor call.

Thanks. That confirms my understanding of the mechanism after John's 
clarification. I will move my code to the cdevpriv destructor and do 
away with the d_close method entirely.

- Bartosz