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#### 14.2.10.2.2 UNLOCK Operations

Unlock operations also act as a one-way permeable barrier. It guarantees that all memory operations before the UNLOCK operation will appear to happen before the UNLOCK operation with respect to the other components of the system.

Memory operations that occur after an UNLOCK operation may appear to happen before it completes.

LOCK and UNLOCK operations are guaranteed to appear with respect to each other strictly in the order specified.

The use of LOCK and UNLOCK operations generally precludes the need for other sorts of memory barrier (but note the exceptions mentioned in the subsection "MMIO write barrier").

Quick Quiz 14.10: What effect does the following sequence have on the order of stores to variables ``a'' and ``b''?
`a = 1;`
`b = 1;`
`<write barrier>` End Quick Quiz