[SSI-devel] [ ssic-linux-Bugs-1718329 ] Problem with migration of process using tcp socket

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Bugs item #1718329, was opened at 2007-05-13 17:25
Message generated for change (Comment added) made by rogertsang
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Category: Process Management
Group: v1.9.2
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: ch0hlik (ch0hlik)
Assigned to: Nobody/Anonymous (nobody)
Summary: Problem with migration of process using tcp socket

Initial Comment:
For example I use this little tcp server:
http://www.cs.rpi.edu/courses/sysprog/sockets/server.c
$ gcc -o server server.c

On the first node 10.0.0.1:
$ ./server 8888

$ migrate 2 server_pid

On the second node 10.0.0.2:
$ telnet 10.0.0.1 8888
Trying 10.0.0.1...
Connected to openone (10.0.0.1).
Escape character is '^]'.
Connection closed by foreign host.

After this server show:
ERROR reading from socket: Invalid argument

In 1.2.2 I'm the same steps and it works fine.
In 1.9.3 problem looks just like in 1.9.2 or worse. (1.9.3 from here: http://radian.org/~roger/OPENSSI-FC/kernel/2.6.11/)

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>Comment By: Roger Tsang (rogertsang)
Date: 2007-08-13 03:05

Message:
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Looking at the code again... In SSI-1.9 the base kernel-2.6 inode
structure no longer directly references its socket structure unlike in
SSI-1.2.  Unless the contents of this socket structure is exported to the
destination node along with the inode SSI-1.9 rmtsocksvr_* operations that
use SOCKET_I() are still working with bugus information from the local
node's sock_inode_cache.  This explains why TCP sockets did not get
recreated properly on the destination migration node.

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Comment By: ch0hlik (ch0hlik)
Date: 2007-06-06 15:18

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Is there is any possibilities that socket migration will be supported in
1.9.2 od 1.9.3?

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Comment By: Roger Tsang (rogertsang)
Date: 2007-05-14 03:10

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According to reop_import_pathinit() the current OpenSSI implementation
does not support socket migration.  However for some reason existing
outbound connections continue even after process migration.  The migration
code looks pretty much the same in SSI-1.2 and SSI-1.9.

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Comment By: Roger Tsang (rogertsang)
Date: 2007-05-13 23:59

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In 2.6.11-ssi TCP socket did not get recreated properly at the destination
node.

At origin node:
server  236031 root    3u  IPv4 121308792                TCP *:8888
(LISTEN)

At destination node:
server  236031 root    3u  sock    0,2          121308792 can't identify
protocol

When migrating the process back to the origin node, the listen socket
reappears.

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