From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radu Nicolau Subject: Re: [PATCH v2] mbuf: use refcnt = 0 when debugging Date: Mon, 4 Sep 2017 15:27:55 +0100 Message-ID: References: <1502120243-8902-1-git-send-email-ciwillia@brocade.com> <1502122274-15657-1-git-send-email-ciwillia@brocade.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: olivier.matz@6wind.com To: "Charles (Chas) Williams" , dev@dpdk.org Return-path: Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by dpdk.org (Postfix) with ESMTP id 65D733989 for ; Mon, 4 Sep 2017 16:27:57 +0200 (CEST) In-Reply-To: <1502122274-15657-1-git-send-email-ciwillia@brocade.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 8/7/2017 5:11 PM, Charles (Chas) Williams wrote: > After commit 8f094a9ac5d7 ("mbuf: set mbuf fields while in pool") is it > much harder to detect a "double free". If the developer makes a copy > of an mbuf pointer and frees it twice, this condition is never detected > and the mbuf gets returned to the pool twice. > > Since this requires extra work to track, make this behavior conditional > on CONFIG_RTE_LIBRTE_MBUF_DEBUG. > > Signed-off-by: Chas Williams > --- > > @@ -1304,10 +1329,13 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) > m->next = NULL; > m->nb_segs = 1; > } > +#ifdef RTE_LIBRTE_MBUF_DEBUG > + rte_mbuf_refcnt_set(m, RTE_MBUF_UNUSED_CNT); > +#endif > > return m; > > - } else if (rte_atomic16_add_return(&m->refcnt_atomic, -1) == 0) { > + } else if (rte_mbuf_refcnt_update(m, -1) == 0) { Why replace the use of atomic operation? > > > if (RTE_MBUF_INDIRECT(m)) > @@ -1317,7 +1345,7 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) > m->next = NULL; > m->nb_segs = 1; > } > - rte_mbuf_refcnt_set(m, 1); > + rte_mbuf_refcnt_set(m, RTE_MBUF_UNUSED_CNT); > > return m; > } Reviewed-by: Radu Nicolau