RCU

Read - Copy - Update

Supplemental Response 23 October 2003 (63-A)

Pages 7-19: Linux kernel 2.5.69

This document, dated the 23rd day of October 20003 (sic), listed 591 files "which may, on information and belief, include information (including methods) that IBM was required to maintain as confidential or proprietary pursuant to contract with SCO and/or which constitute trade secrets misused by IBM are found within Linux 2.4 and/or Linux 2.5 kernels under the following source file headings". There followed what was apparently a lightly filtered list of every file in the Linux 2.5.69 kernel [download] that contain the words "SMP", "RCU" and "NUMA", plus all the JFS files. See Frank Sorenson's superb analysis. Of those 591 files, the 11 files listed below are those that contain the word "RCU".

fs/compat.c
fs/dcache.c
fs/namei.c
include/linux/list.h
include/linux/rcupdate.h
ipc/util.c
ipc/util.h
kernel/rcupdate.c
net/bridge/br_if.c
net/bridge/br_private.h
net/decnet/dn_route.c

Total 11 files

Revised Supplemental Response 15 January 2004 (103-1)

Pages 4-7: the rclock patch

The files listed are from the first rclock patch (for Linux 2.4.1) [download] from the Linux Scalability Effort rclock project. The patch was released on 9 April 2001. The patch touches a total of 14 files, of which nine are listed in the document. The other files are Documentation/rclock.txt, arch/i386/config.in, kernel/Makefile, kernel/ksyms.c and kernel/sched.c.

Total 9 files

The same information is present in the subsequent Second Amended Complaint of 27 February 2004 (108), which remains in effect today, and also in the rejected Third Amended Complaint of 14 October 2004 (323-1).

The inclusion of arch/i386/kernel/apic.c may explain the subsequent bizarre objection to a patch against it - see Item 236.

Pages 7-13: Linux kernel 2.6.0

The files listed are from Linux 2.6.0 [download] [copying]. It was released on 18 December 2003. The next release was 2.6.1 on 9 January 2004. This document is dated 15 January 2004. It catalogues use of RCU in the Kernel - "These files use RCU functions and macros - and if they are used, then the RCU functionality is used, too. The number of lines and number of files, although substantial, is less significant than the impact of the changes, which is dramatic for networking, device drivers, lists, and directory access."

Total 55 files

Hatch letter 19 April 2004 (157-28-D)

Exhibit D: the rclock patch

As in the previous Revised Supplemental Response of 15 January 2004 (103-1 discussed above), the files listed are from the first rclock patch (for Linux 2.4.1) [download] from the Linux Scalability Effort rclock project which was released on 9 April 2001. This document supplements the previous one by providing specific line numbers for the four files previously objected to in their entirety. In three out of four cases, an considerable discrepancy is revealed between the number of lines said to have been directly copied from Dynix/ptx and the number of lines said to be in Linux.

Total 4 files, 1248 lines

Gupta Declaration 7 July 2004 (467)

Pages 4-11: Linux kernel 2.6.5 and rclock patch

Gupta attempts to demonstrate substantial similarity between RCU in the Linux kernel version 2.6.5 and RCU in UNIX SVR4.2 MP (aka 4.2 ES/MP). The five acts he names are (i) "allocating a new data structure of a certain size", and, as revealed in IBM's reply (247 page 8), (ii) "copying the contents of the old data structure to the new data structure", (iii) "updating the new data structure", (iv) "updating or redirecting a pointer to point to the new data structure", and (v) arranging for deferred deletion of the old data structure". He goes on to complain of the first rclock patch for Linux 2.4.1 discussed above [download]. The entire patch is printed, in its unexpurgated unified diff glory, as Gupta's Exhibit E (497 p73-116).

Page 11: IPC locks breakup patch

At paragraph 29 Gupta states: "Another patch was also provided to Linux version 2.5.44 by IBM employee Mingming Cao. See Exhibit G. This patch appears to be incorporated into the Linux version 2.6." The patch printed in Exhibit G (497 p141-158) is in fact the Linux Scalability Effort's IPC Locks Breakup patch ipc-rcu-2544.patch [download]. The patch touches the following files:

include/linux/ipc.h
ipc/msg.c
ipc/sem.c
ipc/shm.c
ipc/util.c
ipc/util.h

Final Disclosure 22 December 2005

Item 2 (ongoing): Read-Copy-Update code [SCO 724 p.8]. Line-for-line copied code from derived works of System V created by IBM (or otherwise protected under the contracts) and contributed to Linux in violations of the IBM and Sequent Software Agreements [SCO 724 Appx A pp.2-3].

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