patches for DPDK stable branches
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From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: Olivier Matz <olivier.matz@6wind.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "andrew.rybchenko@oktetlabs.ru" <andrew.rybchenko@oktetlabs.ru>,
	"mb@smartsharesystems.com" <mb@smartsharesystems.com>,
	"alialnu@nvidia.com" <alialnu@nvidia.com>,
	"ajitkhaparde@gmail.com" <ajitkhaparde@gmail.com>,
	"stable@dpdk.org" <stable@dpdk.org>,
	Ajit Khaparde <ajit.khaparde@broadcom.com>
Subject: Re: [dpdk-stable] [PATCH v3] mbuf: fix reset on mbuf free
Date: Mon, 11 Jan 2021 13:14:16 +0000
Message-ID: <BYAPR11MB3301E703BC2129EFA798397F9AAB0@BYAPR11MB3301.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20210106133333.12528-1-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
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.29.2


  parent reply	other threads:[~2021-01-11 13:14 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-04 17:00 [dpdk-stable] [PATCH] " Olivier Matz
2020-11-05  0:15 ` Ananyev, Konstantin
2020-11-05  7:46   ` Olivier Matz
2020-11-05  8:33     ` [dpdk-stable] [dpdk-dev] " 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-stable] [PATCH v2] " Olivier Matz
2020-12-18 13:18   ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2020-12-18 23:33     ` Ajit Khaparde
2021-01-06 13:33 ` [dpdk-stable] [PATCH v3] " Olivier Matz
2021-01-10  9:28   ` Ali Alnubani
2021-01-11 13:14   ` Ananyev, Konstantin [this message]
2021-01-13 13:27 ` [dpdk-stable] [PATCH v4] " Olivier Matz
2021-01-15 13:59   ` 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               ` [dpdk-stable] [dpdk-dev] " 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           ` [dpdk-stable] " Slava Ovsiienko
2021-07-24  8:47             ` [dpdk-stable] [dpdk-dev] " 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
2021-01-21  9:19       ` [dpdk-stable] " Ferruh Yigit
2021-01-21  9:29         ` [dpdk-stable] [dpdk-dev] " Morten Brørup
2021-01-21 16:35           ` [dpdk-stable] [dpdklab] " Lincoln Lavoie
2021-01-23  8:57             ` [dpdk-stable] [dpdk-dev] [dpdklab] " Morten Brørup
2021-01-25 17:00               ` Brandon Lo
2021-01-25 18:42             ` [dpdk-stable] [dpdklab] RE: [dpdk-dev] " Ferruh Yigit
2021-06-15 13:56   ` [dpdk-stable] " Morten Brørup

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