Deadlock Characterization

Necessary conditions:

1) Mutual exclusion:
• at least one shared resource is held
2) Hold and wait:
• a process must be holding at least one resource and
waiting for another
3) No preemption:
• cannot steal a resource away from a process
4) Circular wait:
• E.g., A is waiting for B who is waiting for C who is
waiting for A.