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Subject: questions about pinned external buffers
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Thread-Topic: questions about pinned external buffers
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Shahaf Shuler" <shahafs@nvidia.com>,
 "Viacheslav Ovsiienko" <viacheslavo@nvidia.com>, <dev@dpdk.org>
Cc: "Olivier Matz" <olivier.matz@6wind.com>,
	<thomas@monjalon.net>
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Pinned external buffers were introduced with this patch:
https://git.dpdk.org/dpdk/commit/lib/librte_mbuf/rte_mbuf.h?id=3D6ef1107a=
d4c6d4fcb6be627367ee0b97bb13e822

Question 1:
Please confirm that the mbuf's pinned external buffer's refcnt is =
supposed to be 1 when an mbuf is returned to the mempool?

If so, the below assertion should be updated for completion:

rte_mbuf_raw_free(struct rte_mbuf *m)
{
	RTE_ASSERT(!RTE_MBUF_CLONED(m) &&
-			(!RTE_MBUF_HAS_EXTBUF(m) || RTE_MBUF_HAS_PINNED_EXTBUF(m)));
+			(!RTE_MBUF_HAS_EXTBUF(m) ||
+			(RTE_MBUF_HAS_PINNED_EXTBUF(m) &&
+			rte_mbuf_ext_refcnt_read(m->shinfo) =3D=3D 1)));
	__rte_mbuf_raw_sanity_check(m);
	rte_mempool_put(m->pool, m);
}

The increased performance cost should be acceptable for debug builds =
(i.e. with assertions enabled).

Question 2:
Could this assertion be moved to __rte_mbuf_raw_sanity_check()?

I'm working on a new rte_mbuf_raw_free_bulk() function, for use with =
RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE; and if the assertion is not moved to =
__rte_mbuf_raw_sanity_check(), it needs to be copy-pasted into the new =
raw_free_bulk() function too.