From: "Morten Brørup" <mb@smartsharesystems.com>
To: dev@dpdk.org
Cc: "Morten Brørup" <mb@smartsharesystems.com>
Subject: [PATCH] net: improve vlan header type alignment
Date: Sun, 13 Oct 2024 08:35:54 +0000 [thread overview]
Message-ID: <20241013083554.97489-1-mb@smartsharesystems.com> (raw)
Ethernet packets can be VLAN tagged, i.e. an Ethernet header can have a
VLAN tag (a.k.a. VLAN header) embedded.
Since the Ethernet header is 2 byte aligned, and the VLAN tag is directly
related to the Ethernet header, the VLAN tag is also 2 byte aligned, so
packing the VLAN tag structure is not necessary.
Furthermore, the Ethernet header type is implictly 2 byte aligned, so
removed the superfluous explicit 2 byte alignment.
Added static_asserts to verify the size and alignment of the various
Ethernet types.
Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
lib/net/rte_ether.h | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/lib/net/rte_ether.h b/lib/net/rte_ether.h
index 403e84f50b..c9a0b536c3 100644
--- a/lib/net/rte_ether.h
+++ b/lib/net/rte_ether.h
@@ -11,6 +11,8 @@
* Ethernet Helpers in RTE
*/
+#include <assert.h>
+#include <stdalign.h>
#include <stdint.h>
#include <stdio.h>
@@ -75,6 +77,11 @@ struct __rte_aligned(2) rte_ether_addr {
uint8_t addr_bytes[RTE_ETHER_ADDR_LEN]; /**< Addr bytes in tx order */
};
+static_assert(sizeof(struct rte_ether_addr) == 6,
+ "sizeof(struct rte_ether_addr) == 6");
+static_assert(alignof(struct rte_ether_addr) == 2,
+ "alignof(struct rte_ether_addr) == 2");
+
#define RTE_ETHER_LOCAL_ADMIN_ADDR 0x02 /**< Locally assigned Eth. address. */
#define RTE_ETHER_GROUP_ADDR 0x01 /**< Multicast or broadcast Eth. address. */
@@ -290,12 +297,17 @@ rte_ether_unformat_addr(const char *str, struct rte_ether_addr *eth_addr);
* Ethernet header: Contains the destination address, source address
* and frame type.
*/
-struct __rte_aligned(2) rte_ether_hdr {
+struct rte_ether_hdr {
struct rte_ether_addr dst_addr; /**< Destination address. */
struct rte_ether_addr src_addr; /**< Source address. */
rte_be16_t ether_type; /**< Frame type. */
};
+static_assert(sizeof(struct rte_ether_hdr) == 14,
+ "sizeof(struct rte_ether_hdr) == 14");
+static_assert(alignof(struct rte_ether_hdr) == 2,
+ "alignof(struct rte_ether_hdr) == 2");
+
/**
* Ethernet VLAN Header.
* Contains the 16-bit VLAN Tag Control Identifier and the Ethernet type
@@ -304,7 +316,12 @@ struct __rte_aligned(2) rte_ether_hdr {
struct rte_vlan_hdr {
rte_be16_t vlan_tci; /**< Priority (3) + CFI (1) + Identifier Code (12) */
rte_be16_t eth_proto; /**< Ethernet type of encapsulated frame. */
-} __rte_packed;
+};
+
+static_assert(sizeof(struct rte_vlan_hdr) == 4,
+ "sizeof(struct rte_vlan_hdr) == 4");
+static_assert(alignof(struct rte_vlan_hdr) == 2,
+ "alignof(struct rte_vlan_hdr) == 2");
--
2.43.0
next reply other threads:[~2024-10-13 8:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-13 8:35 Morten Brørup [this message]
2024-10-13 8:51 ` Morten Brørup
2024-10-14 5:42 ` fengchengwen
2024-10-14 8:04 ` Bruce Richardson
2024-10-17 20:44 ` Thomas Monjalon
2024-10-17 23:41 ` Morten Brørup
2024-10-18 9:11 ` Thomas Monjalon
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