In traditional UNIX systems, every section of kernel code terminates either through an explicit call to sleep(1) to give up the processor or through a hardware interrupt. The Oracle Solaris OS operates differently. A kernel thread can be preempted at any time to run another thread. Because all kernel threads share kernel address space and often need to read and modify the same data, the kernel provides a number of locking primitives to prevent threads from corrupting shared data. These mechanisms include mutual exclusion locks, which are also known as mutexes, readers/writer locks, and semaphores.