* [PATCH v2] ethdev: fix strict aliasing lead to link cannot be up
@ 2024-04-11 11:58 Chengwen Feng
0 siblings, 0 replies; only message in thread
From: Chengwen Feng @ 2024-04-11 11:58 UTC (permalink / raw)
To: thomas, ferruh.yigit; +Cc: dev, huangdengdui, mb, stephen, roretzla
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.
[1] Strict aliasing problem with rte_eth_linkstatus_set()
https://marc.info/?l=dpdk-dev&m=171274148514777&w=3
Cc: stable@dpdk.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Dengdui Huang <huangdengdui@huawei.com>
---
v2: add RTE_ATOMIC(uint64_t) wrap which address Morten's comment.
---
lib/ethdev/ethdev_driver.h | 23 +++++++----------------
lib/ethdev/rte_ethdev.h | 16 ++++++++++------
2 files changed, 17 insertions(+), 22 deletions(-)
diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
index 0dbf2dd6a2..9d831d5c84 100644
--- a/lib/ethdev/ethdev_driver.h
+++ b/lib/ethdev/ethdev_driver.h
@@ -1674,18 +1674,13 @@ 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;
}
/**
@@ -1701,12 +1696,8 @@ 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));
-
- *dst = rte_atomic_load_explicit(src, rte_memory_order_seq_cst);
+ link->val64 = rte_atomic_load_explicit(&dev->data->dev_link.val64,
+ rte_memory_order_seq_cst);
}
/**
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 147257d6a2..ccf43e468a 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -332,12 +332,16 @@ struct rte_eth_stats {
/**
* A structure used to retrieve link-level information of an Ethernet port.
*/
-__extension__
-struct __rte_aligned(8) rte_eth_link { /**< aligned for atomic64 read/write */
- 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] */
+struct rte_eth_link {
+ union {
+ RTE_ATOMIC(uint64_t) val64; /**< used for atomic64 read/write */
+ 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
--
2.17.1
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