Synchronization Issues
As you'll soon see, you can alter how the kernel perceives the operating system's state by manipulating the various kernel queue data structures. However, you risk damaging the system by simply traversing and/or modifying these objects by virtue of being preemptible; that is, if your code is interrupted and another thread accesses or manipulates the same objects that you were manipulating, data corruption can result. Moreover, with symmetric multiprocessing (SMP), preemption isn't even necessary; if your code is running on one CPU, while another thread on another CPU is manipulating the same object, data corruption can occur.
To safely manipulate the kernel queue data structures—that is, in order to ensure thread synchronization—your ...
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