From bdc14ddec75a529e6ecf327e78d5746c120247ff Mon Sep 17 00:00:00 2001
From: Chengwen Feng <fengchengwen@huawei.com>
Date: Mon, 22 Apr 2024 06:38:13 +0000
Subject: [PATCH] ethdev: fix strict aliasing lead to link cannot be up
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[ upstream commit 8841786ab4aa72d205f97528af8708a13a851f4f ]

Fix a problem introduced by a compiler upgrade (from gcc10 to gcc12.3),
which will lead the hns3 NIC can't link up. The root cause is strict
aliasing violation in rte_eth_linkstatus_set() with hns3 driver, see
[1] for more details.

This commit use union to avoid such aliasing violation. Also the
impacted components (cxgbe and qos_sched) have been adapted to the
struct change.

[1] https://inbox.dpdk.org/dev/8175c905-e661-b910-7f20-59b6ab605c38@huawei.com/

Cc: stable@dpdk.org

Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Dengdui Huang <huangdengdui@huawei.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Ferruh Yigit <ferruh.yigit@amd.com>
---
 drivers/net/cxgbe/cxgbe_ethdev.c |  3 ++-
 examples/qos_sched/init.c        |  3 ++-
 lib/ethdev/ethdev_driver.h       | 24 +++++++++---------------
 lib/ethdev/rte_ethdev.h          | 17 +++++++++++------
 4 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/drivers/net/cxgbe/cxgbe_ethdev.c b/drivers/net/cxgbe/cxgbe_ethdev.c
index 8cc3d9f..781f48c 100644
--- a/drivers/net/cxgbe/cxgbe_ethdev.c
+++ b/drivers/net/cxgbe/cxgbe_ethdev.c
@@ -211,9 +211,9 @@ int cxgbe_dev_link_update(struct rte_eth_dev *eth_dev,
 	unsigned int i, work_done, budget = 32;
 	struct link_config *lc = &pi->link_cfg;
 	struct adapter *adapter = pi->adapter;
-	struct rte_eth_link new_link = { 0 };
 	u8 old_link = pi->link_cfg.link_ok;
 	struct sge *s = &adapter->sge;
+	struct rte_eth_link new_link;
 
 	for (i = 0; i < CXGBE_LINK_STATUS_POLL_CNT; i++) {
 		if (!s->fw_evtq.desc)
@@ -232,6 +232,7 @@ int cxgbe_dev_link_update(struct rte_eth_dev *eth_dev,
 		rte_delay_ms(CXGBE_LINK_STATUS_POLL_MS);
 	}
 
+	memset(&new_link, 0, sizeof(new_link));
 	new_link.link_status = cxgbe_force_linkup(adapter) ?
 			       RTE_ETH_LINK_UP : pi->link_cfg.link_ok;
 	new_link.link_autoneg = (lc->link_caps & FW_PORT_CAP32_ANEG) ? 1 : 0;
diff --git a/examples/qos_sched/init.c b/examples/qos_sched/init.c
index d8abae6..32964fd 100644
--- a/examples/qos_sched/init.c
+++ b/examples/qos_sched/init.c
@@ -335,7 +335,7 @@ int app_init(void)
 	for(i = 0; i < nb_pfc; i++) {
 		uint32_t socket = rte_lcore_to_socket_id(qos_conf[i].rx_core);
 		struct rte_ring *ring;
-		struct rte_eth_link link = {0};
+		struct rte_eth_link link;
 		int retry_count = 100, retry_delay = 100; /* try every 100ms for 10 sec */
 
 		snprintf(ring_name, MAX_NAME_LEN, "ring-%u-%u", i, qos_conf[i].rx_core);
@@ -367,6 +367,7 @@ int app_init(void)
 		app_init_port(qos_conf[i].rx_port, qos_conf[i].mbuf_pool);
 		app_init_port(qos_conf[i].tx_port, qos_conf[i].mbuf_pool);
 
+		memset(&link, 0, sizeof(link));
 		rte_eth_link_get(qos_conf[i].tx_port, &link);
 		if (link.link_status == 0)
 			printf("Waiting for link on port %u\n", qos_conf[i].tx_port);
diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
index b482cd1..ec56925 100644
--- a/lib/ethdev/ethdev_driver.h
+++ b/lib/ethdev/ethdev_driver.h
@@ -1655,18 +1655,13 @@ static inline int
 rte_eth_linkstatus_set(struct rte_eth_dev *dev,
 		       const struct rte_eth_link *new_link)
 {
-	RTE_ATOMIC(uint64_t) *dev_link = (uint64_t __rte_atomic *)&(dev->data->dev_link);
-	union {
-		uint64_t val64;
-		struct rte_eth_link link;
-	} orig;
-
-	RTE_BUILD_BUG_ON(sizeof(*new_link) != sizeof(uint64_t));
+	struct rte_eth_link old_link;
 
-	orig.val64 = rte_atomic_exchange_explicit(dev_link, *(const uint64_t *)new_link,
-					rte_memory_order_seq_cst);
+	old_link.val64 = rte_atomic_exchange_explicit(&dev->data->dev_link.val64,
+						      new_link->val64,
+						      rte_memory_order_seq_cst);
 
-	return (orig.link.link_status == new_link->link_status) ? -1 : 0;
+	return (old_link.link_status == new_link->link_status) ? -1 : 0;
 }
 
 /**
@@ -1682,12 +1677,11 @@ static inline void
 rte_eth_linkstatus_get(const struct rte_eth_dev *dev,
 		       struct rte_eth_link *link)
 {
-	RTE_ATOMIC(uint64_t) *src = (uint64_t __rte_atomic *)&(dev->data->dev_link);
-	uint64_t *dst = (uint64_t *)link;
-
-	RTE_BUILD_BUG_ON(sizeof(*link) != sizeof(uint64_t));
+	struct rte_eth_link curr_link;
 
-	*dst = rte_atomic_load_explicit(src, rte_memory_order_seq_cst);
+	curr_link.val64 = rte_atomic_load_explicit(&dev->data->dev_link.val64,
+						   rte_memory_order_seq_cst);
+	rte_atomic_store_explicit(&link->val64, curr_link.val64, rte_memory_order_seq_cst);
 }
 
 /**
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 57a9a55..b95ae69 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -331,13 +331,18 @@ struct rte_eth_stats {
 /**
  * A structure used to retrieve link-level information of an Ethernet port.
  */
-__extension__
 struct rte_eth_link {
-	uint32_t link_speed;        /**< RTE_ETH_SPEED_NUM_ */
-	uint16_t link_duplex  : 1;  /**< RTE_ETH_LINK_[HALF/FULL]_DUPLEX */
-	uint16_t link_autoneg : 1;  /**< RTE_ETH_LINK_[AUTONEG/FIXED] */
-	uint16_t link_status  : 1;  /**< RTE_ETH_LINK_[DOWN/UP] */
-} __rte_aligned(8);      /**< aligned for atomic64 read/write */
+        union {
+                RTE_ATOMIC(uint64_t) val64; /**< used for atomic64 read/write */
+                __extension__
+                struct {
+                        uint32_t link_speed;        /**< RTE_ETH_SPEED_NUM_ */
+                        uint16_t link_duplex  : 1;  /**< RTE_ETH_LINK_[HALF/FULL]_DUPLEX */
+                        uint16_t link_autoneg : 1;  /**< RTE_ETH_LINK_[AUTONEG/FIXED] */
+                        uint16_t link_status  : 1;  /**< RTE_ETH_LINK_[DOWN/UP] */
+                };
+        };
+};
 
 /**@{@name Link negotiation
  * Constants used in link management.
-- 
2.33.0

