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Subject: bugs in rte_pktmbuf_copy
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Date: Mon, 17 Nov 2025 12:51:51 +0100
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Thread-Topic: bugs in rte_pktmbuf_copy
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: <stephen@networkplumber.org>,
	<dev@dpdk.org>
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While working on a rte_pktmbuf_copy_bulk() function, I noticed a couple =
of bugs in rte_pktmbuf_copy():

1. If the copy is allocated from a mempool using pinned external =
buffers, the copy's RTE_MBUF_F_EXTERNAL flag is lost.
This is simple to fix:

-	/* copied mbuf is not indirect or external */
-	mc->ol_flags =3D m->ol_flags & =
~(RTE_MBUF_F_INDIRECT|RTE_MBUF_F_EXTERNAL);
+	/* copy flags except indirect and external */
+	mc->ol_flags |=3D m->ol_flags & =
~(RTE_MBUF_F_INDIRECT|RTE_MBUF_F_EXTERNAL);

2. If the packet is copied with non-zero offset, much of the metadata do =
not apply to the copy, e.g. many of the offload flags and the =
packet_type field.
Maybe metadata should be reset when copying with a non-zero offset?
Or maybe rte_pktmbuf_copy() should be considered "payload copy", so the =
copy should have all metadata reset?


Venlig hilsen / Kind regards,
-Morten Br=F8rup