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<p class="MsoNormal"><span style="font-size:11.0pt">Hi David,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I will look into this at earliest and provide feedback.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> David Marchand <david.marchand@redhat.com>
<br>
<b>Sent:</b> Friday, February 7, 2025 2:20 PM<br>
<b>To:</b> Jerin Jacob <jerinj@marvell.com>; Sunil Kumar Kori <skori@marvell.com><br>
<b>Cc:</b> dev@dpdk.org; Chengwen Feng <fengchengwen@huawei.com>; Kevin Laatz <kevin.laatz@intel.com>; Bruce Richardson <bruce.richardson@intel.com>; Tyler Retzlaff <roretzla@linux.microsoft.com>; Andre Muezerie <andremue@linux.microsoft.com>; Thomas Monjalon
<thomas@monjalon.net>; Stephen Hemminger <stephen@networkplumber.org><br>
<b>Subject:</b> [EXTERNAL] Re: [PATCH v2 3/3] trace: fix undefined behavior in register<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="mso-line-height-alt:.75pt"><span style="font-size:1.0pt;color:white">Hello Jerin, Sunil, On Thu, Jan 30, 2025 at 3:</span><span style="font-size:1.0pt;font-family:"Arial",sans-serif;color:white"> </span><span style="font-size:1.0pt;color:white">59
PM David Marchand <david.</span><span style="font-size:1.0pt;font-family:"Arial",sans-serif;color:white"> </span><span style="font-size:1.0pt;color:white">marchand@</span><span style="font-size:1.0pt;font-family:"Arial",sans-serif;color:white"> </span><span style="font-size:1.0pt;color:white">redhat.</span><span style="font-size:1.0pt;font-family:"Arial",sans-serif;color:white"> </span><span style="font-size:1.0pt;color:white">com>
wrote: > > Registering a tracepoint handler was resulting so far in undefined > behavior at runtime. > > The RTE_TRACE_POINT_REGISTER()<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-line-height-alt:.75pt"><span style="font-size:1.0pt;color:white"><o:p></o:p></span></p>
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<pre style="white-space:pre-wrap"><span style="font-size:12.0pt;font-family:"Arial",sans-serif">Hello Jerin, Sunil,<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">On Thu, Jan 30, 2025 at 3:59 PM David Marchand<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><<a href="mailto:david.marchand@redhat.com">david.marchand@redhat.com</a>> wrote:<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> Registering a tracepoint handler was resulting so far in undefined<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> behavior at runtime.<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> The RTE_TRACE_POINT_REGISTER() macro was casting the tracepoint handler<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> (which expects arguments) to a void (*)(void).<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> At runtime, calling this handler while registering resulted in<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> reading the current stack with no relation to this function prototype.<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> Instead, declare an additional inline _register() handler for each<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> tracepoint and make sure that the emitting macros in<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> rte_trace_point_register.h only work on arguments name and type.<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> The original tracepoint handler prototype is adjusted by adding a<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> __rte_unused for each argument (since emitting macros do nothing<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> with them).<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> This last part introduces an implementation limit of 15 arguments.<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> With this change in place, the workaround in dmadev tracepoints can be<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> removed.<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">> Signed-off-by: David Marchand <<a href="mailto:david.marchand@redhat.com">david.marchand@redhat.com</a>><o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">Can I have your opinion and review on this patch?<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">Thanks.<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">-- <o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif">David Marchand<o:p></o:p></span></pre>
<pre><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></pre>
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