Re: A question about communication between kernel, daemon
H. Peter Anvin (hpa@transmeta.com)
21 Aug 1998 02:13:59 GMT
Followup to: <19980820180530.9736.qmail@hotmail.com>
By author: "Cook Dan" <tricountry@hotmail.com>
In newsgroup: linux.dev.kernel
>
> Hello,
>
> I have a question about the communication between Linux kernel, and
> one daemon on that host. What is the better way to let kernel inform
> a daemon something happened. I know signal should work, But somehow
> I do not want to use it. I did not use unix socket before, But since
> unix socket will use a file, It seems it can not be used in kernel.
>
> The problem I ran into looks like this:
>
> Kernel receive a message, this message is not aimed to one application,
> but the kernel needs to handle it, and will pass
> this message to a daemon after the kernel handling. And daemon
> will also handle this message.
>
> Thanks. Please also cc to me.
>
autofs uses a pipe, which works great as long as you don't need to
handle messages larger than PIPE_BUF (4K); if so then you need a
semaphore around the places in the kernel which write to the pipe to
avoid interleaved packet fragments.
It's really easy to do, to. Look at fs/autofs/inode.c and look for
"fget".
-hpa
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