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This is an automatically generated e-mail. To reply, visit:
<a href="https://reviewboard.asterisk.org/r/1563/">https://reviewboard.asterisk.org/r/1563/</a>
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<p style="margin-top: 0;">On November 4th, 2011, 12:35 p.m., <b>mjordan</b> wrote:</p>
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<a href="https://reviewboard.asterisk.org/r/1563/diff/2/?file=21625#file21625line25012" style="color: black; font-weight: bold; text-decoration: underline;">trunk/channels/chan_sip.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 handle_request_subscribe(struct sip_pvt *p, struct sip_request *req, struct ast_sockaddr *addr, int seqno, const char *e)</pre></td>
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<td bgcolor="#c5ffc4" width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>
<th bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid #C0C0C0;" align="right"><font size="2">25011</font></th>
<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">p</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;">Same here with respect to unlocking / locking p</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;">It is going to be best to clear all locks before calling sip_send_mwi_to_peer().
This is weird, but it is possible in some really strange edge case that the peer->mwipvt accessed in the send_mwi function is not the same as the sip_pvt locked before entering this function. Since we lock the peer->mwipvt now during the transmit function we should enter the sip_send_mwi_to_peer with no locks held to guarantee no deadlocks occur due to two sip_pvt locks being held at the same time. It is also safer not to hold the sip_peer and sip_pvt lock at the same time when at all possible. If we enter the function with a sip_pvt locked we can not guarantee this.
Also, this function has the potential to block because of the voicemail count function which may access the disk. If recursive locks are held before this function is executed, we can not guarantee all locks are let go when the voicemail count is retrieved.</pre>
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<p>- David</p>
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<p>On November 4th, 2011, 11:16 a.m., opticron wrote:</p>
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<div>Review request for Asterisk Developers and David Vossel.</div>
<div>By opticron.</div>
<p style="color: grey;"><i>Updated Nov. 4, 2011, 11:16 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;">Fix a locking inversion that causes deadlocks during BLF subscriptions.</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;">Compile</pre>
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<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="https://issues.asterisk.org/jira/browse/ASTERISK-18663">ASTERISK-18663</a>
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<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
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<li>trunk/channels/chan_sip.c <span style="color: grey">(342600)</span></li>
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<p><a href="https://reviewboard.asterisk.org/r/1563/diff/" style="margin-left: 3em;">View Diff</a></p>
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