From: Olivier Matz <olivier.matz@6wind.com>
To: dev@dpdk.org
Cc: andrew.rybchenko@oktetlabs.ru, konstantin.ananyev@intel.com,
mb@smartsharesystems.com, alialnu@nvidia.com,
ajitkhaparde@gmail.com, stable@dpdk.org,
Ajit Khaparde <ajit.khaparde@broadcom.com>
Subject: [dpdk-dev] [PATCH v3] mbuf: fix reset on mbuf free
Date: Wed, 6 Jan 2021 14:33:33 +0100 [thread overview]
Message-ID: <20210106133333.12528-1-olivier.matz@6wind.com> (raw)
In-Reply-To: <20201104170007.8026-1-olivier.matz@6wind.com>
m->nb_seg must be reset on mbuf free whatever the value of m->next,
because it can happen that m->nb_seg is != 1. For instance in this
case:
m1 = rte_pktmbuf_alloc(mp);
rte_pktmbuf_append(m1, 500);
m2 = rte_pktmbuf_alloc(mp);
rte_pktmbuf_append(m2, 500);
rte_pktmbuf_chain(m1, m2);
m0 = rte_pktmbuf_alloc(mp);
rte_pktmbuf_append(m0, 500);
rte_pktmbuf_chain(m0, m1);
As rte_pktmbuf_chain() does not reset nb_seg in the initial m1
segment (this is not required), after this code the mbuf chain
have 3 segments:
- m0: next=m1, nb_seg=3
- m1: next=m2, nb_seg=2
- m2: next=NULL, nb_seg=1
Then split this chain between m1 and m2, it would result in 2 packets:
- first packet
- m0: next=m1, nb_seg=2
- m1: next=NULL, nb_seg=2
- second packet
- m2: next=NULL, nb_seg=1
Freeing the first packet will not restore nb_seg=1 in the second
segment. This is an issue because it is expected that mbufs stored
in pool have their nb_seg field set to 1.
Fixes: 8f094a9ac5d7 ("mbuf: set mbuf fields while in pool")
Cc: stable@dpdk.org
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
---
v3
* fix commit log again (thanks Morten for spotting it)
v2
* avoid write access if uneeded (suggested by Konstantin)
* enhance comments in mbuf header file (suggested by Morten)
* fix commit log
lib/librte_mbuf/rte_mbuf.c | 4 ++--
lib/librte_mbuf/rte_mbuf.h | 8 ++++----
lib/librte_mbuf/rte_mbuf_core.h | 13 +++++++++++--
3 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 7d09ee2939..5f77840557 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -129,10 +129,10 @@ rte_pktmbuf_free_pinned_extmem(void *addr, void *opaque)
rte_mbuf_ext_refcnt_set(m->shinfo, 1);
m->ol_flags = EXT_ATTACHED_MBUF;
- if (m->next != NULL) {
+ if (m->next != NULL)
m->next = NULL;
+ if (m->nb_segs != 1)
m->nb_segs = 1;
- }
rte_mbuf_raw_free(m);
}
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index c4c9ebfaa0..8c1097ed76 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1340,10 +1340,10 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
return NULL;
}
- if (m->next != NULL) {
+ if (m->next != NULL)
m->next = NULL;
+ if (m->nb_segs != 1)
m->nb_segs = 1;
- }
return m;
@@ -1357,10 +1357,10 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
return NULL;
}
- if (m->next != NULL) {
+ if (m->next != NULL)
m->next = NULL;
+ if (m->nb_segs != 1)
m->nb_segs = 1;
- }
rte_mbuf_refcnt_set(m, 1);
return m;
diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h
index 567551deab..78a1fcc8ff 100644
--- a/lib/librte_mbuf/rte_mbuf_core.h
+++ b/lib/librte_mbuf/rte_mbuf_core.h
@@ -495,7 +495,12 @@ struct rte_mbuf {
* or non-atomic) is controlled by the RTE_MBUF_REFCNT_ATOMIC flag.
*/
uint16_t refcnt;
- uint16_t nb_segs; /**< Number of segments. */
+
+ /**
+ * Number of segments. Only valid for the first segment of an mbuf
+ * chain.
+ */
+ uint16_t nb_segs;
/** Input port (16 bits to support more than 256 virtual ports).
* The event eth Tx adapter uses this field to specify the output port.
@@ -591,7 +596,11 @@ struct rte_mbuf {
/* second cache line - fields only used in slow path or on TX */
RTE_MARKER cacheline1 __rte_cache_min_aligned;
- struct rte_mbuf *next; /**< Next segment of scattered packet. */
+ /**
+ * Next segment of scattered packet. Must be NULL in the last segment or
+ * in case of non-segmented packet.
+ */
+ struct rte_mbuf *next;
/* fields to support TX offloads */
RTE_STD_C11
--
2.29.2
next prev parent reply other threads:[~2021-01-06 13:33 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-04 17:00 [dpdk-dev] [PATCH] " Olivier Matz
2020-11-05 0:15 ` Ananyev, Konstantin
2020-11-05 7:46 ` Olivier Matz
2020-11-05 8:26 ` Andrew Rybchenko
2020-11-05 9:10 ` Olivier Matz
2020-11-05 11:34 ` Ananyev, Konstantin
2020-11-05 12:31 ` Olivier Matz
2020-11-05 13:14 ` Ananyev, Konstantin
2020-11-05 13:24 ` Olivier Matz
2020-11-05 13:55 ` Ananyev, Konstantin
2020-11-05 16:30 ` Morten Brørup
2020-11-05 23:55 ` Ananyev, Konstantin
2020-11-06 7:52 ` Morten Brørup
2020-11-06 8:20 ` Olivier Matz
2020-11-06 8:50 ` Morten Brørup
2020-11-06 10:04 ` Olivier Matz
2020-11-06 10:07 ` Morten Brørup
2020-11-06 11:53 ` Ananyev, Konstantin
2020-11-06 12:23 ` Morten Brørup
2020-11-08 14:16 ` Andrew Rybchenko
2020-11-08 14:19 ` Ananyev, Konstantin
2020-11-10 16:26 ` Olivier Matz
2020-11-05 8:33 ` Morten Brørup
2020-11-05 9:03 ` Olivier Matz
2020-11-05 9:09 ` Andrew Rybchenko
2020-11-08 7:25 ` Ali Alnubani
2020-12-18 12:52 ` [dpdk-dev] [PATCH v2] " Olivier Matz
2020-12-18 13:18 ` Morten Brørup
2020-12-18 23:33 ` Ajit Khaparde
2021-01-06 13:33 ` Olivier Matz [this message]
2021-01-10 9:28 ` [dpdk-dev] [PATCH v3] " Ali Alnubani
2021-01-11 13:14 ` Ananyev, Konstantin
2021-01-13 13:27 ` [dpdk-dev] [PATCH v4] " Olivier Matz
2021-01-15 13:59 ` [dpdk-dev] [dpdk-stable] " David Marchand
2021-01-15 18:39 ` Ali Alnubani
2021-01-18 17:52 ` Ali Alnubani
2021-01-19 8:32 ` Olivier Matz
2021-01-19 8:53 ` Morten Brørup
2021-01-19 12:00 ` Ferruh Yigit
2021-01-19 12:27 ` Morten Brørup
2021-01-19 14:03 ` Ferruh Yigit
2021-01-19 14:21 ` Morten Brørup
2021-01-21 9:15 ` Ferruh Yigit
2021-01-19 14:04 ` Slava Ovsiienko
2021-07-24 8:47 ` Thomas Monjalon
2021-07-30 12:36 ` Olivier Matz
2021-07-30 14:35 ` Morten Brørup
2021-07-30 14:54 ` Thomas Monjalon
2021-07-30 15:14 ` Olivier Matz
2021-07-30 15:23 ` Morten Brørup
2021-08-04 13:29 ` [dpdk-dev] [PATCH] doc: add known issue with mbuf segment Thomas Monjalon
2021-08-04 14:25 ` Ajit Khaparde
2021-08-05 6:08 ` Morten Brørup
2021-08-06 14:21 ` Thomas Monjalon
2021-08-06 14:24 ` Morten Brørup
2021-09-28 8:28 ` [dpdk-dev] [dpdk-stable] [PATCH v4] mbuf: fix reset on mbuf free Thomas Monjalon
2021-09-28 9:00 ` Slava Ovsiienko
2021-09-28 9:25 ` Ananyev, Konstantin
2021-09-28 9:39 ` Morten Brørup
2021-09-29 8:03 ` Ali Alnubani
2021-09-29 21:39 ` Olivier Matz
2021-09-30 13:29 ` Ali Alnubani
2021-10-21 8:26 ` Thomas Monjalon
2021-01-21 9:19 ` Ferruh Yigit
2021-01-21 9:29 ` Morten Brørup
2021-01-21 16:35 ` [dpdk-dev] [dpdklab] " Lincoln Lavoie
2021-01-23 8:57 ` Morten Brørup
2021-01-25 17:00 ` Brandon Lo
2021-01-25 18:42 ` Ferruh Yigit
2021-06-15 13:56 ` [dpdk-dev] " Morten Brørup
2021-09-29 21:37 ` [dpdk-dev] [PATCH v5] " Olivier Matz
2021-09-30 13:27 ` Ali Alnubani
2021-10-21 9:18 ` David Marchand
2022-07-28 14:06 ` CI performance test results might be misleading Morten Brørup
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