Duplicate headers in tools/testing/shared directory diverged - rcupdate.h

[Shuah Khan <skhan@linuxfoundation.org>]

All,

I am sending this email to you all because you touched tools/testing/shared
and its sub directories and show up in

get_maintainer.pl -f tools/testing/shared/ output

rbtree compile failed as it couldn't find urcu.h

cc -I../shared -I. -I../../include -I../../arch/x86/include -I../../../lib -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address -fsanitize=undefined    -c -o rbtree_test.o rbtree_test.c
In file included from ../shared/shared.h:11,
                  from rbtree_test.c:9:
../shared/linux/rcupdate.h:5:10: fatal error: urcu.h: No such file or directory
     5 | #include <urcu.h>
       |          ^~~~~~~~
compilation terminated.

This sent me down the path to look at the duplicate headers in tools/testing/shared
especially rcupdate.h which is under tools/testing/shared/linux

It appears this file is an exact copy of include/linux/rcupdate.h and now it
diverged. Why do we have these duplicate headers here in this shared
directory - it appears they are out of date and lead to maintenance problems.

thanks,
-- Shuah