CONFIG_GUSA_RB is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Implement atomic operations by roll-back (gRB) (EXPERIMENTAL)

configname: CONFIG_GUSA_RB

Linux Kernel Configuration
└─>Kernel features
└─>Implement atomic operations by roll-back (gRB) (EXPERIMENTAL)
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
Enabling this option will allow the kernel to implement some
atomic operations using a software implementation of load-locked/
store-conditional (LLSC). On machines which do not have hardware
LLSC, this should be more efficient than the other alternative of
disabling interrupts around the atomic sequence.