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<p dir="auto">As you already said, on all supported platform the read and write to/from int already is atomic. Making the variable atomic just helps unsupported platforms (e.g. 16 bit data bus).</p>
<p dir="auto">What I think of is code like</p>
<pre class="code highlight js-syntax-highlight plaintext" lang="plaintext" v-pre="true"><code><span id="LC1" class="line" lang="plaintext">if (session->internals.recv_state != RECV_STATE_FALSE_START &&</span>
<span id="LC2" class="line" lang="plaintext"> session->internals.recv_state != RECV_STATE_FALSE_START_HANDLING &&</span>
<span id="LC3" class="line" lang="plaintext"> session->internals.recv_state != RECV_STATE_EARLY_START &&</span>
<span id="LC4" class="line" lang="plaintext"> session->internals.recv_state != RECV_STATE_EARLY_START_HANDLING &&</span>
<span id="LC5" class="line" lang="plaintext"> !(session->internals.hsk_flags & HSK_EARLY_DATA_IN_FLIGHT))</span>
<span id="LC6" class="line" lang="plaintext">...</span></code></pre>
<p dir="auto">If a non-optimizing compiler reads the variable 4x, this allows a second thread to change the value between two comparisons. It might be unlikely, but to be sure you would save <code>session->internals.recv_state</code> into a temp variable and use that for comparison.</p>
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