Description of problem:

Failed to build radix tree test suite in kernel source tree by
linking to EPEL7 userspace-rcu library.

Using upstream git://git.liburcu.org/userspace-rcu.git libs instead
will fix this issue.

sh-4.2# pwd
/root/linux
sh-4.2# make -C tools/testing/radix-tree/
make: Entering directory `/root/linux/tools/testing/radix-tree'
cc -I. -I../../include -g -O2 -Wall -D_LGPL_SOURCE -lpthread -lurcu main.o radix-tree.o linux.o test.o tag_check.o find_next_bit.o regression1.o regression2.o regression3.o multiorder.o iteration_check.o benchmark.o -o main
multiorder.o: In function `multiorder_join3':
/root/linux/tools/testing/radix-tree/multiorder.c:415: undefined reference to `rcu_barrier'
iteration_check.o: In function `untagged_iteration_fn':
/root/linux/tools/testing/radix-tree/iteration_check.c:128: undefined reference to `rcu_barrier'
/root/linux/tools/testing/radix-tree/iteration_check.c:128: undefined reference to `rcu_barrier'
iteration_check.o: In function `tagged_iteration_fn':
/root/linux/tools/testing/radix-tree/iteration_check.c:87: undefined reference to `rcu_barrier'
/root/linux/tools/testing/radix-tree/iteration_check.c:87: undefined reference to `rcu_barrier'
main.o:/root/linux/tools/testing/radix-tree/main.c:294: more undefined references to `rcu_barrier' follow
collect2: error: ld returned 1 exit status
make: *** [main] Error 1
make: Leaving directory `/root/linux/tools/testing/radix-tree'
sh-4.2# 

Version-Release number of selected component (if applicable):

sh-4.2# rpm -qv userspace-rcu
userspace-rcu-0.7.16-1.el7.x86_64
sh-4.2# rpm -qv userspace-rcu-devel
userspace-rcu-devel-0.7.16-1.el7.x86_64
sh-4.2# uname -r
3.10.0-514.2.2.el7.x86_64
sh-4.2# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 7.3 (Maipo)

How reproducible:
always

Steps to Reproduce:
1. download lates Linus kernel tree
2. setup epel7 && install userspace-rcu-devel
3. in linux tree, make -C tools/testing/radix-tree

Actual results:
ld failure

Expected results:
build success

Additional info: