Date: Mon, 6 Feb 2006 14:56:49 -0800 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: Raaf <freebsd@luna.afraid.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Freeing mmapped memory Message-ID: <20060206225649.GJ69162@funkthat.com> In-Reply-To: <43E7C583.3040904@luna.afraid.org> References: <43E7C583.3040904@luna.afraid.org>
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Raaf wrote this message on Mon, Feb 06, 2006 at 22:54 +0100:
> Hi, i am working on a usb driver that allocates some memory when
> the device is opened using malloc.
>
> Now i want user processes to be able to access this memory using
> mmap and i want to free this memory when it is no longer needed.
>
> The problem is that there seems to be no way of knowing for my
> driver at what time the memory is no longer mapped in a process
> address space so that i can safely free this memory.
why not at close time? I would imagine that the device won't be closed
until all the mmap's that are backed by the device are unmapped.. it
shouldn't be hard to test... the mapping should hold a reference to
the device until it's munmapped..
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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