From: Thomas Monjalon <thomas@monjalon.net>
To: Ruifeng Wang <Ruifeng.Wang@arm.com>,
Min Zhou <zhoumin@loongson.cn>,
dev@dpdk.org, "Zhang, Qi Z" <qi.z.zhang@intel.com>
Cc: "mb@smartsharesystems.com" <mb@smartsharesystems.com>,
"konstantin.v.ananyev@yandex.ru" <konstantin.v.ananyev@yandex.ru>,
"Yang, Qiming" <qiming.yang@intel.com>,
"Wu, Wenjun1" <wenjun1.wu@intel.com>,
"drc@linux.vnet.ibm.com" <drc@linux.vnet.ibm.com>,
"roretzla@linux.microsoft.com" <roretzla@linux.microsoft.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"stable@dpdk.org" <stable@dpdk.org>,
"maobibo@loongson.cn" <maobibo@loongson.cn>, nd <nd@arm.com>,
david.marchand@redhat.com
Subject: Re: [PATCH v3] net/ixgbe: add proper memory barriers for some Rx functions
Date: Mon, 12 Jun 2023 12:26:06 +0200 [thread overview]
Message-ID: <3202143.AJdgDx1Vlc@thomas> (raw)
In-Reply-To: <DM4PR11MB59940F773E4CEF01650A392BD7789@DM4PR11MB5994.namprd11.prod.outlook.com>
15/05/2023 04:10, Zhang, Qi Z:
> From: Ruifeng Wang <Ruifeng.Wang@arm.com>
> > From: Min Zhou <zhoumin@loongson.cn>
> > >
> > > Segmentation fault has been observed while running the
> > > ixgbe_recv_pkts_lro() function to receive packets on the Loongson
> > > 3C5000 processor which has 64 cores and 4 NUMA nodes.
> > >
> > > From the ixgbe_recv_pkts_lro() function, we found that as long as the
> > > first packet has the EOP bit set, and the length of this packet is
> > > less than or equal to rxq->crc_len, the segmentation fault will
> > > definitely happen even though on the other platforms. For example, if
> > > we made the first packet which had the EOP bit set had a zero length by
> > force, the segmentation fault would happen on X86.
> > >
> > > Because when processd the first packet the first_seg->next will be
> > > NULL, if at the same time this packet has the EOP bit set and its
> > > length is less than or equal to rxq->crc_len, the following loop will be
> > executed:
> > >
> > > for (lp = first_seg; lp->next != rxm; lp = lp->next)
> > > ;
> > >
> > > We know that the first_seg->next will be NULL under this condition. So
> > > the expression of
> > > lp->next->next will cause the segmentation fault.
> > >
> > > Normally, the length of the first packet with EOP bit set will be
> > > greater than rxq-
> > > >crc_len. However, the out-of-order execution of CPU may make the read
> > > >ordering of the
> > > status and the rest of the descriptor fields in this function not be
> > > correct. The related codes are as following:
> > >
> > > rxdp = &rx_ring[rx_id];
> > > #1 staterr = rte_le_to_cpu_32(rxdp->wb.upper.status_error);
> > >
> > > if (!(staterr & IXGBE_RXDADV_STAT_DD))
> > > break;
> > >
> > > #2 rxd = *rxdp;
> > >
> > > The sentence #2 may be executed before sentence #1. This action is
> > > likely to make the ready packet zero length. If the packet is the
> > > first packet and has the EOP bit set, the above segmentation fault will
> > happen.
> > >
> > > So, we should add a proper memory barrier to ensure the read ordering
> > > be correct. We also did the same thing in the ixgbe_recv_pkts()
> > > function to make the rxd data be valid even though we did not find
> > segmentation fault in this function.
> > >
> > > Fixes: 8eecb3295ae ("ixgbe: add LRO support")
> > > Cc: stable@dpdk.org
> > >
> > > Signed-off-by: Min Zhou <zhoumin@loongson.cn>
> > > ---
> > > v3:
> > > - Use rte_smp_rmb() as the proper memory barrier instead of rte_rmb()
> > > ---
> > > v2:
> > > - Make the calling of rte_rmb() for all platforms
> > > ---
[...]
> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
>
> Applied to dpdk-next-net-intel.
>
> Thanks
> Qi
>
Why ignoring checkpatch?
It is saying:
"
Warning in drivers/net/ixgbe/ixgbe_rxtx.c:
Using rte_smp_[r/w]mb
"
Ruifeng proposed "rte_atomic_thread_fence(__ATOMIC_ACQUIRE)"
in a comment on the v2.
I will drop this patch from the pull of next-net-intel branch.
next prev parent reply other threads:[~2023-06-12 10:26 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-24 9:05 [PATCH v2] " Min Zhou
2023-04-28 3:43 ` Zhang, Qi Z
2023-04-28 6:27 ` Morten Brørup
2023-05-04 12:58 ` zhoumin
2023-05-04 12:42 ` zhoumin
2023-05-01 13:29 ` Konstantin Ananyev
2023-05-04 6:13 ` Ruifeng Wang
2023-05-05 1:45 ` zhoumin
2023-05-04 13:16 ` zhoumin
2023-05-04 13:21 ` Morten Brørup
2023-05-04 13:33 ` Zhang, Qi Z
2023-05-05 2:42 ` zhoumin
2023-05-06 1:30 ` Zhang, Qi Z
2023-05-05 1:54 ` zhoumin
2023-05-06 10:23 ` [PATCH v3] " Min Zhou
2023-05-08 6:03 ` Ruifeng Wang
2023-05-15 2:10 ` Zhang, Qi Z
2023-06-12 10:26 ` Thomas Monjalon [this message]
2023-06-12 11:58 ` zhoumin
2023-06-12 12:44 ` Thomas Monjalon
2023-06-13 1:42 ` zhoumin
2023-06-13 3:30 ` Jiawen Wu
2023-06-13 10:12 ` zhoumin
2023-06-14 10:58 ` Konstantin Ananyev
2023-06-13 9:25 ` Ruifeng Wang
2023-06-20 15:52 ` Thomas Monjalon
2023-06-21 6:50 ` Ruifeng Wang
2023-06-13 9:44 ` [PATCH v4] " Min Zhou
2023-06-13 10:20 ` Ruifeng Wang
2023-06-13 12:11 ` Zhang, Qi Z
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