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This is an automatically generated e-mail. To reply, visit:
<a href="https://reviewboard.asterisk.org/r/1752/">https://reviewboard.asterisk.org/r/1752/</a>
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<p style="margin-top: 0;">On February 22nd, 2012, 1:11 p.m., <b>wdoekes</b> wrote:</p>
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<a href="https://reviewboard.asterisk.org/r/1752/diff/2/?file=24509#file24509line1811" style="color: black; font-weight: bold; text-decoration: underline;">/trunk/res/res_calendar.c</a>
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(Diff revision 2)
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<td colspan="4"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">static int unload_module(void)</pre></td>
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<th bgcolor="#f0f0f0" style="border-right: 1px solid #C0C0C0;" align="right"><font size="2">1809</font></th>
<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">AST_LIST_TRAVERSE_SAFE_BEGIN</span><span class="p">(</span><span class="o">&</span><span class="n">techs</span><span class="p">,</span> <span class="n">tech</span><span class="p">,</span> <span class="n">list</span><span class="p">)</span> <span class="p">{</span></pre></td>
<th bgcolor="#f0f0f0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid #C0C0C0;" align="right"><font size="2">1811</font></th>
<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">AST_LIST_TRAVERSE_SAFE_BEGIN</span><span class="p">(</span><span class="o">&</span><span class="n">techs</span><span class="p">,</span> <span class="n">tech</span><span class="p">,</span> <span class="n">list</span><span class="p">)</span> <span class="p">{</span></pre></td>
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<th bgcolor="#f0f0f0" style="border-right: 1px solid #C0C0C0;" align="right"><font size="2">1810</font></th>
<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">ast_unload_resource</span><span class="p">(</span><span class="n">tech</span><span class="o">-></span><span class="n">module</span><span class="p">,</span> <span class="mi">0</span><span class="p">);</span></pre></td>
<th bgcolor="#f0f0f0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid #C0C0C0;" align="right"><font size="2">1812</font></th>
<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">ast_unload_resource</span><span class="p">(</span><span class="n">tech</span><span class="o">-></span><span class="n">module</span><span class="p">,</span> <span class="mi">0</span><span class="p">);</span></pre></td>
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<th bgcolor="#f0f0f0" style="border-right: 1px solid #C0C0C0;" align="right"><font size="2">1811</font></th>
<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="p">}</span></pre></td>
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<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="p">}</span></pre></td>
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<th bgcolor="#f0f0f0" style="border-right: 1px solid #C0C0C0;" align="right"><font size="2">1812</font></th>
<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">AST_LIST_TRAVERSE_SAFE_END</span><span class="p">;</span></pre></td>
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<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">AST_LIST_TRAVERSE_SAFE_END</span><span class="p">;</span></pre></td>
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<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">If it's now not possible to unload res_calendar before unloading those that depend on it, shouldn't this be replaced with an assert(AST_LIST_EMPTY(&techs)) ?</pre>
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<pre style="margin-left: 1em; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Bah. Indeed. The whole point originally was to be able to unload res_calendar and the dependent modules with "module unload res_calendar.so". Oh, well. At least this makes it obvious why it isn't unloading in that case and still allows it to shut down properly.</pre>
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<p>- Terry</p>
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<p>On February 22nd, 2012, 12:12 p.m., Terry Wilson wrote:</p>
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<div>Review request for Asterisk Developers.</div>
<div>By Terry Wilson.</div>
<p style="color: grey;"><i>Updated Feb. 22, 2012, 12:12 p.m.</i></p>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">res_calendar calls ast_unload_resource for the related tech modules when it is unloaded. If this happens through a 'core stop gracefully', then it will be unloading the tech modules that are already in the list that is being traversed (supposedly safely) for unloading, eventually causing a double free. The problem seems to be that ast_unload_resource, while it calls the unload() callback function for the module, does not actually unlink the module from the list of modules. So the AST_LIST_TRAVERSE_SAFE_BEGIN {} still iterates over the unloaded module.
This patch causes ast_unload_resource to call AST_LIST_REMOVE on successfully unloaded modules.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
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<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Scenario: Start Asterisk with res_calendar and assorted calendar tech modules loaded. Run 'core stop gracefully'.
Before patch: Crash.
After patch: No crash.</pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>/trunk/include/asterisk/calendar.h <span style="color: grey">(356213)</span></li>
<li>/trunk/main/loader.c <span style="color: grey">(356213)</span></li>
<li>/trunk/res/res_calendar.c <span style="color: grey">(356213)</span></li>
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<p><a href="https://reviewboard.asterisk.org/r/1752/diff/" style="margin-left: 3em;">View Diff</a></p>
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