How atomic update is implemented in Coroutines

Question

Here's update function from Coroutines StateFlow. I have two questions:

1. How is it atomic? We have multiple operations inside, how can atomicity be guaranteed without mutual exclusion?
2. Why is it in while(true) loop? At what condition the loop is necessary?
3. Can the loop be endless?

/**
 * Updates the [MutableStateFlow.value] atomically using the specified [function] of its value.
 *
 * [function] may be evaluated multiple times, if [value] is being concurrently updated.
 */
public inline fun <T> MutableStateFlow<T>.update(function: (T) -> T) {
    while (true) {
        val prevValue = value
        val nextValue = function(prevValue)
        if (compareAndSet(prevValue, nextValue)) {
            return
        }
    }
}