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    <p><strong>Historical context:</strong> We should remember that Dijkstra wrote <em><a href="http://www.u.arizona.edu/~rubinson/copyright_violations/Go_To_Considered_Harmful.html" rel="noreferrer">Goto Considered Harmful</a></em> in 1968, when a lot of programmers used <code>goto</code> as a replacement for <a href="http://en.wikipedia.org/wiki/Structured_programming" rel="noreferrer">structured programming</a> (<code>if</code>, <code>while</code>, <code>for</code>, etc.). </p> <p>It's 44 years later, and it's rare to find this use of <code>goto</code> in the wild. Structured programming has already won, long ago.</p> <p><strong>Case analysis:</strong></p> <p>The example code looks like this:</p> <pre><code> SETUP... again: COMPUTE SOME VALUES... if (cmpxchg64(ptr, old_val, val) != old_val) goto again; </code></pre> <p>The structured version looks like this:</p> <pre><code>SETUP... do { COMPUTE SOME VALUES... } while (cmpxchg64(ptr, old_val, val) != old_val); </code></pre> <p>When I look at the structured version, I immediately think, "it's a loop". When I look at the <code>goto</code> version, I think of it as a straight line with a "try again" case at the end.</p> <p>The <code>goto</code> version has both <code>SETUP</code> and <code>COMPUTE SOME VALUES</code> on the same column, which emphasizes that most of the time, control flow passes through both. The structured version puts <code>SETUP</code> and <code>COMPUTE SOME VALUES</code> on different columns, which emphasizes that control may pass through them differently.</p> <p>The question here is what kind of emphasis do you want to put in the code? You can compare this with <code>goto</code> for error handling:</p> <p>Structured version:</p> <pre><code>if (do_something() != ERR) { if (do_something2() != ERR) { if (do_something3() != ERR) { if (do_something4() != ERR) { ... </code></pre> <p>Goto version:</p> <pre><code>if (do_something() == ERR) // Straight line goto error; // | if (do_something2() == ERR) // | goto error; // | if (do_something3() == ERR) // | goto error; // V if (do_something4() == ERR) // emphasizes normal control flow goto error; </code></pre> <p>The code generated is basically the same, so we can think of it as a typographical concern, like indentation.</p>
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    1. POWhy do some kernel programmers use goto instead of simple while loops?
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    1. CO[Kernel programmers agree](http://programmers.stackexchange.com/a/154980/27881). If you had ERR1, ERR2... ERRN, then you could `goto clean_err1;`/etc and reverse the changes as though it was stack.
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    2. CO+1 for showing how goto can emphasize the expected control flow.
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