Hello, everyone.

I have read the book "Design and implementation of the 4.4 BSD".
So I know the packet dataflow is as follows:

device interrupt---> protocol input queue--->software interrupt---> ip_input( )

But after read the files in /usr/src/sys/netinet,
in my opinion, fr_check( ) in ip_fil.c is used as the packet filter entry point.

My question is that fr_check( ) is before or after software interrupt ?

Thank you very much.

sincerely yours
suxm

            suxm@gnuchina.org