Re: Which process is associated with process ID 0 (swapper)

From: Mikado
Date: Thu Apr 20 2006 - 11:58:05 EST


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linux-os (Dick Johnson) wrote:
> This must be a trick question. Linux is not VAX/VMS. There is no
> swapper process. Check in /proc. Processes start at 1. Even
> kernel threads have PIDs greater than 1.

Linux really has swapper process ;)

> Portions of the kernel networking code operate detached. The code
> gets the CPU from a timer queue or from an interrupt. When an
> connection is attempted, the process attempting the connection
> is either waiting, with its CPU time being used, or put to
> sleep, while the timer queue's CPU time is being used. The
> SYN/ACK handshake is handled during this time, therefore it
> is possible to find who is attempting that connection. Netstat
> gets that information from /proc/net and multiple socket
> calls.

I'm writing kernel module that hooks into netfilter code. I can catch
packet's information and its owner process. The first SYN packet of
handshaking belongs to real user-space socket/process. After timeout,
several SYN packets are generated by kernel-space swapper process (PID
0) Is there anyway to find out the relationship between them in
_kernel_space_ (module context).

Thanks,
Mikado.
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