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From: Bin Zheng <zhengbin.89740@bytedance.com>
To: dev@dpdk.org
Cc: haiyue.wang@intel.com, liangma@liangbit.com,
	Bin Zheng <zhengbin.89740@bytedance.com>,
	jia.guo@intel.com, stable@dpdk.org
Subject: [PATCH v2 1/2] net/ixgbe: add vector Rx parameter check
Date: Thu,  2 Dec 2021 17:20:00 +0800	[thread overview]
Message-ID: <20211202092001.1830481-1-zhengbin.89740@bytedance.com> (raw)

Under the circumstance that `rx_tail` wrap back to zero
and the advance speed of `rx_tail` is greater than `rxrearm_start`,
`rx_tail` will catch up with `rxrearm_start` and surpass it.
This may cause some mbufs be reused by application.

So we need to make some restrictions to ensure that
 `rx_tail` will not exceed `rxrearm_start`.

e.g.

RDH: 972 RDT: 991 rxrearm_nb: 991 rxrearm_start: 992 rx_tail: 959
RDH: 1004 RDT: 1023 rxrearm_nb: 991 rxrearm_start: 0 rx_tail: 991
RDH: 12 RDT: 31 rxrearm_nb: 991 rxrearm_start: 32 rx_tail: 1023
RDH: 31 RDT: 63 rxrearm_nb: 960 rxrearm_start: 64 rx_tail: 0
RDH: 95 RDT: 95 rxrearm_nb: 1016 rxrearm_start: 96 rx_tail: 88
RDH: 95 RDT: 127 rxrearm_nb: 991 rxrearm_start: 128 rx_tail: 95
...
RDH: 908 RDT: 927 rxrearm_nb: 991 rxrearm_start: 928 rx_tail: 895
RDH: 940 RDT: 959 rxrearm_nb: 991 rxrearm_start: 960 rx_tail: 927
RDH: 980 RDT: 991 rxrearm_nb: 991 rxrearm_start: 992 rx_tail: 959
RDH: 991 RDT: 991 rxrearm_nb: 1026 rxrearm_start: 992 rx_tail: 994

when `rx_tail` catches up with `rxrearm_start`,
2(994 - 992) mbufs be reused by application !

Bugzilla ID: 882
Fixes: 5a3cca342417 ("net/ixgbe: fix vector Rx")
Cc: jia.guo@intel.com
Cc: stable@dpdk.org

Signed-off-by: Bin Zheng <zhengbin.89740@bytedance.com>
---
 drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
index 1eed949495..5811749b95 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
@@ -364,6 +364,17 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 	uint8_t vlan_flags;
 	uint16_t udp_p_flag = 0; /* Rx Descriptor UDP header present */
 
+	/*
+	 * Under the circumstance that `rx_tail` wrap back to zero
+	 * and the advance speed of `rx_tail` is greater than `rxrearm_start`,
+	 * `rx_tail` will catch up with `rxrearm_start` and surpass it.
+	 * This may cause some mbufs be reused by applicaion.
+	 *
+	 * So we need to make some restrictions to ensure that
+	 * `rx_tail` will not exceed `rxrearm_start`.
+	 */
+	nb_pkts = RTE_MIN(nb_pkts, RTE_IXGBE_RXQ_REARM_THRESH);
+
 	/* nb_pkts has to be floor-aligned to RTE_IXGBE_DESCS_PER_LOOP */
 	nb_pkts = RTE_ALIGN_FLOOR(nb_pkts, RTE_IXGBE_DESCS_PER_LOOP);
 
-- 
2.25.1


             reply	other threads:[~2021-12-02  9:20 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-02  9:20 Bin Zheng [this message]
2021-12-02  9:20 ` [PATCH v2 2/2] net/ixgbe: fix spelling mistakes Bin Zheng
2021-12-02 12:53   ` Wang, Haiyue
2021-12-10  8:22   ` [PATCH v3] net/ixgbe: add vector Rx parameter check Bin Zheng
2021-12-13  3:02     ` Rong, Leyi
2021-12-14  7:29       ` Wang, Haiyue
2022-01-11  0:31         ` Zhang, Qi Z
2021-12-15  8:07     ` Liang Ma

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