linux-kernel - Re: userspace notification from module

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Message-ID: <4B3F5264.7000008@gmail.com>
Date:	Sat, 02 Jan 2010 15:04:20 +0100
From:	Daniel Borkmann <danborkmann@...glemail.com>
To:	Bartłomiej Zimoń <uzi18@...pl>
CC:	linux-kernel@...r.kernel.org
Subject: Re: userspace notification from module

Hi Bartłomiej,

Bartłomiej Zimoń wrote:
> Dnia 2 stycznia 2010 13:36 	Daniel Borkmann <llug.dan@...glemail.com> napisał(a):
> I will explain more what i'm going to do.
> The idea is simple. Kernel before suspend/resume sends notification to 
> registered kernel objects. So i have written small module to register
> there and want now pass these data to /dev/file. It is 1byte so not a big deal.
> 
> I'm searching now for notification about new byte in buffer, as it is almost 
> clear for async: http://www.xml.com/ldd/chapter/book/ch05.html#t4
> but for sync still haven't find.

This sounds very interesting... a "hack" could be the following:

Register your pids to the kernel module, e.g. via ioctl, and if the
(intra-kernel) notification will be delivered to your module you just
send a signal to your registered processes via kill_proc_info(). Guess
this is at least better than polling a file or sth similar.

I guess netlink could be the "cleaner" solution, but with more overhead?!

Cheers,
Daniel

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