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Okay, so here the issue is still rte_eth_dev_stop(), but not rte_eth_dev_rx_queue_stop(), right? I mean, as long as not calling rte_eth_dev_stop() on control path, is it safe to call rte_eth_dev_rx_queue_stop/rte_eth_dev_rx_queue_start on control path while
fast path keeps calling rte_eth_rx_burst()? </div>
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<p> </p>
<p><i>Thanks,</i></p>
<p>Changchun</p>
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<div dir="ltr" id="divRplyFwdMsg"><span style="font-family: Calibri, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><b>From:</b> Stephen Hemminger <stephen@networkplumber.org><br>
<b>Sent:</b> Monday, February 17, 2025 2:06 PM<br>
<b>To:</b> Changchun Zhang <changchun.zhang@oracle.com><br>
<b>Cc:</b> Van Haaren, Harry <harry.van.haaren@intel.com>; NAGENDRA BALAGANI <nagendra.balagani@oracle.com>; users@dpdk.org <users@dpdk.org><br>
<b>Subject:</b> Re: [External] : Re: Query Regarding Race Condition Between Packet Reception and Device Stop in DPDK</span>
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<div class="elementToProof" style="font-size: 11pt;">On Mon, 17 Feb 2025 18:57:00 +0000<br>
Changchun Zhang <changchun.zhang@oracle.com> wrote:<br>
<br>
> Hi Harry,<br>
><br>
> Can we call rte_eth_dev_rx_queue_stop() on a rx queue when a fast path is still polling the queue? The sequence on control and fast path cores would like:<br>
> Control path:<br>
> rte_eth_dev_rx_queue_stop(rx_queue_id);<br>
> ...waiting for draining of rx_queue...<br>
> rte_eth_dev_stop()<br>
> ....<br>
><br>
> Fast path:<br>
> Keep calling rte_eth_rx_burst()<br>
> (I am expecting it will return 0 if queue is already drained and stopped)<br>
><br>
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No.<br>
The application needs to not call rx_burst when stop is being done.<br>
There rx_burst is a fast path with no additional checks and is intentionally not thread safe.<br>
You need to coordinate queue management inside the application.</div>
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