Last week’s installment in this
series on lockless patterns took a first look
at the compare-and-swap (CAS) operation. CAS is a powerful tool that can
be used to implement a number of lockless primitives. The next step is to
look at other atomic read-modify-write operations that can
be implemented on top of compare-and-swap.

Source: LWN.net – [$] Lockless patterns: more read-modify-write operations