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This is an automatically generated e-mail. To reply, visit:
<a href="https://reviewboard.asterisk.org/r/1323/">https://reviewboard.asterisk.org/r/1323/</a>
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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;">I'm so confused at how this could happen.... I don't doubt it though.</pre>
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<a href="https://reviewboard.asterisk.org/r/1323/diff/2/?file=17675#file17675line6326" style="color: black; font-weight: bold; text-decoration: underline;">/team/irroot/distrotech-customers-1.8/main/channel.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; ">int ast_do_masquerade(struct ast_channel *original)</pre></td>
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<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * until we unlock the container. */</span></pre></td>
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<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * until we unlock the container. */</span></pre></td>
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<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="k">while</span> <span class="p">(</span><span class="n">ast_channel_trylock</span><span class="p">(</span><span class="n">clonechan</span><span class="p">))</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="k">while</span> <span class="p">(</span><span class="n">ast_channel_trylock</span><span class="p">(</span><span class="n">clonechan</span><span class="p">))</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">CHANNEL_DEADLOCK_AVOIDANCE</span><span class="p">(</span><span class="n">original</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">CHANNEL_DEADLOCK_AVOIDANCE</span><span class="p">(</span><span class="n">original</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="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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<td bgcolor="#ffffff" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="cm">/* recheck if masq has been done the deadlock avoidance above could cause a double masq</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span class="cm"> * this is posible with at least ast_hangup*/</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">original</span><span class="o">-></span><span class="n">masq</span><span class="p">)</span> <span class="p">{</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">ast_channel_unlock</span><span class="p">(</span><span class="n">original</span><span class="p">);</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">ast_channel_unlock</span><span class="p">(</span><span class="n">clonechan</span><span class="p">);</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="n">ao2_unlock</span><span class="p">(</span><span class="n">channels</span><span class="p">);</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="k">return</span> <span class="mi">0</span><span class="p">;</span> <span class="cm">/* masq already completed by another thread, or never needed to be done to begin with */</span></pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span class="p">}</span></pre></td>
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<pre style="margin-left: 2em; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">seems like this check on original->masq should be done in the while loop up there during deadlock avoidance. Otherwise how are we guaranteed clonechan pointer is good for locking/unlocking
while ((clonechan = original->masq) && ast_channel_trylock(clonechan)) {
DEADLOCK_AVOIDANCE(original)
}
/*no clone chan, bail */
if (!original->masq) {
unlock original
unlock channels
return 0;
}</pre>
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<p>- David</p>
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<p>On July 29th, 2011, 11:12 a.m., irroot wrote:</p>
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<div>Review request for Asterisk Developers.</div>
<div>By irroot.</div>
<p style="color: grey;"><i>Updated July 29, 2011, 11:12 a.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;">seems like app_queue [and others likely] can leave a orphaned channel with no bridge and no thread running on it.
this is "ungood" here is a small patch that starts auto service waits for bridging and turns it off allowing the
hangup frame to get through and shut down the channel ... </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;">[Jul 29 09:23:57] NOTICE[9698] app_directed_pickup.c: pickup SIP/0207-000002d3 attempt by SIP/0226-000002d5
[Jul 29 09:23:58] WARNING[9698] chan_sip.c: No SIP tech_pvt! Fixup of SIP/0226-000002d5 failed.
[Jul 29 09:23:58] WARNING[9698] channel.c: Fixup failed on channel SIP/0226-000002d5<MASQ>, strange things may happen.
[Jul 29 09:25:10] NOTICE[10465] chan_sip.c: Disconnecting call 'SIP/0226-000002d5' for lack of RTP activity in 61 seconds
it seems possible this is a race condition between ast_hangup and ast_do_masquerade
do_masq holds the channels container [not allowing the channels to be unlinked] it also holds the original channel
ast_hangup hold origchan but will unlock it to run do_masq
do_masq will release the origchannel to avoid a deadlock with the clonechannel when this happens do_masq will run twice and orig chan will be removed by hangup
clonechan will be striped of all dignity </pre>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>/team/irroot/distrotech-customers-1.8/main/channel.c <span style="color: grey">(330200)</span></li>
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<p><a href="https://reviewboard.asterisk.org/r/1323/diff/" style="margin-left: 3em;">View Diff</a></p>
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