Date: Wed, 21 Jan 2009 15:40:24 +0200 From: Andriy Gapon <avg@icyb.net.ua> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: device driver: cdesw questions? Message-ID: <497725C8.4010101@icyb.net.ua> In-Reply-To: <20090121133520.GK58517@deviant.kiev.zoral.com.ua> References: <49770513.8090203@icyb.net.ua> <20090121133520.GK58517@deviant.kiev.zoral.com.ua>
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on 21/01/2009 15:35 Kostik Belousov said the following: > On Wed, Jan 21, 2009 at 01:20:51PM +0200, Andriy Gapon wrote: >> Question 1: >> I am writing a driver that would use per-open private data (among other >> features). >> Do I have to use D_TRACKCLOSE flag in this case? > No, the dtr registered with devfs_set_cdevpriv(), is called exactly once > when the last close is performed, or the device is destroyed. Kostik, thanks a lot for the explanation! I am still a little bit confused about the term "last close" - what is it? I.e. I'd like to get an answer to the below question. >> In general I am a little bit confused about when d_close is invoked. >> Supposing D_TRACKCLOSE is not set and multiple programs concurrently >> open, use and close a device - when d_close is called - when one program >> closes its last descriptor tied to the device or when the system-wide >> last such descriptor is closed? -- Andriy Gapon
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