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<p class="MsoNormal">Hi Team,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In my dpdk application, I am facing an issue where rte_pktmbuf_alloc() is returning same address for two consecutive calls in a single thread context.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Following is the code snippet,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">int Func(struct rte_mbuf *mblk)<o:p></o:p></p>
<p class="MsoNormal">{<o:p></o:p></p>
<p class="MsoNormal"> struct rte_mbuf *tmpbuf = nullptr;;<o:p></o:p></p>
<p class="MsoNormal"> struct rte_mbuf *copybuf = nullptr;<o:p></o:p></p>
<p class="MsoNormal"> char *nextPtr = NULL;<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> <b>tmpbuf = rte_pktmbuf_alloc(mbuf_pool);<o:p></o:p></b></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> nextPtr = rte_pktmbuf_append(tmpbuf, IPV4_HDR_LEN);<o:p></o:p></p>
<p class="MsoNormal"> //update some info on nextptr<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> <b>copybuf = rte_pktmbuf_copy(mblk, mbuf_pool, 0, pkt_len);<o:p></o:p></b></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> ….<o:p></o:p></p>
<p class="MsoNormal"> return 0;<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">With the above snippet, ‘tmpbuf’ and ‘copybuf’ which are getting allocated from same pool (mbuf_pool), pointing to same address, Due to this tmpbuf which gets allocated first, and further populated, is getting over written inside rte_pktmbuf_copy()
call which is not expected .<o:p></o:p></p>
<p class="MsoNormal">When I further debug , rte_pktmbuf_copy() is internally using rte_pktmbuf_alloc() to get the free buffer from mbuf_pool and copy the data from mblk.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please let us know if there is any known issue with rte_pktmbuf_alloc(), and why it may be giving same address on two consecutive calls.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards,<br>
Nagendra<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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