<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
/* List Definitions */
@list l0
{mso-list-id:451823006;
mso-list-type:hybrid;
mso-list-template-ids:1210626014 -1451229078 67698691 67698693 67698689 67698691 67698693 67698689 67698691 67698693;}
@list l0:level1
{mso-level-number-format:bullet;
mso-level-text:-;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:"Calibri","sans-serif";
mso-fareast-font-family:Calibri;
mso-bidi-font-family:"Times New Roman";}
@list l1
{mso-list-id:930509931;
mso-list-type:hybrid;
mso-list-template-ids:186185070 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l1:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l2
{mso-list-id:1185557835;
mso-list-type:hybrid;
mso-list-template-ids:-1017221382 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l2:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal>During the OFA plugfest at UNH I came across a problem in
which a verbs consumer application made a call to ibv_poll_cq after having
called ibv_destroy_qp(). The application segfaults in a call to a module supplied
by a verb provider that is invoked as a result of the call to ibv_destroy_qp().<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>As the writer of the application I am unclear as to ownership
of this problem – is this behavior “badness” in the code of
the verb provider, or is it an issue in my application.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The application is processing an abortive teardown process
in which it is attempting to terminate the RDMA stream and recover associated resources.
The peer at the other end may be doing the same thing at the “same”
time.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The application, when aborting does the following:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Sets the qp_state to IBV_QPS_ERR<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Sleeps for a second<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Calls ibv_destroy_qp<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>4.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Calls ibv_destoy_cq<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The event processing thread is doing the following:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo3'><![if !supportLists]><span
style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Calls bv_get_cq_event<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo3'><![if !supportLists]><span
style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Calls ibv_req_notify_cq<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo3'><![if !supportLists]><span
style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>while((ibv_poll_cq(cq_event, 1, xx) ==1 ) {};<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo3'><![if !supportLists]><span
style='mso-list:Ignore'>4.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>more stuff<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Does the application need to ensure that ibv_poll_cq is
never called after the associated qp is destroyed?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Barry
Reinhold<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>(603) 868-8411<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><a
href="mailto:bbr@lampreynetworks.com"><span style='color:blue'>bbr@lampreynetworks.com</span></a><o:p></o:p></span></p>
<p class=MsoNormal><o:p> </o:p></p>
</div>
</body>
</html>