Draw a timing diagram

Suppose that we implement test-and-set! using an ordinary procedure as shown in the text, without attempting to make the operation atomic. Draw a timing diagram like the one in figure 3.29 to demonstrate how the mutex implementation can fail by allowing two processes to acquire the mutex at the same time.

Figure 3.29: Timing diagram showing how interleaving the order of events in two banking withdrawals can lead to an incorrect final balance.