From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 3F711A09FD; Fri, 18 Dec 2020 13:53:07 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id AC4C3CAE0; Fri, 18 Dec 2020 13:52:43 +0100 (CET) Received: from proxy.6wind.com (host.76.145.23.62.rev.coltfrance.com [62.23.145.76]) by dpdk.org (Postfix) with ESMTP id 3A18BCAAF; Fri, 18 Dec 2020 13:52:41 +0100 (CET) Received: from glumotte.dev.6wind.com. (unknown [10.16.0.195]) by proxy.6wind.com (Postfix) with ESMTP id 176BC4AC307; Fri, 18 Dec 2020 13:52:41 +0100 (CET) From: Olivier Matz To: dev@dpdk.org Cc: andrew.rybchenko@oktetlabs.ru, konstantin.ananyev@intel.com, mb@smartsharesystems.com, stable@dpdk.org Date: Fri, 18 Dec 2020 13:52:37 +0100 Message-Id: <20201218125238.13074-1-olivier.matz@6wind.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201104170007.8026-1-olivier.matz@6wind.com> References: <20201104170007.8026-1-olivier.matz@6wind.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH v2] mbuf: fix reset on mbuf free X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 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=3 - m1: next=m2, 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 --- 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 -- 2.25.1