[v3,5/6] net/ether: mark ethernet addresses as being 2-byte aligned
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Commit Message
From: Bruce Richardson <bruce.richardson@intel.com>
When including the rte_ether.h header in applications with warnings
enabled, a warning was given because of the assumption of 2-byte alignment
of ethernet addresses when processing them.
.../include/rte_ether.h:149:2: warning: converting a packed ‘const
struct ether_addr’ pointer (alignment 1) to a ‘unaligned_uint16_t’
{aka ‘const short unsigned int’} pointer (alignment 2) may result in
an unaligned pointer value [-Waddress-of-packed-member]
149 | const unaligned_uint16_t *ea_words = (const unaligned_uint16_t *)ea;
| ^~~~~
Since ethernet addresses should always be aligned on a two-byte boundary,
we can just inform the compiler of this assumption to remove the warnings
and allow us to always access the addresses using 16-bit operations.
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
lib/librte_net/rte_ether.h | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
Comments
On 6/5/19 4:08 AM, Stephen Hemminger wrote:
> From: Bruce Richardson <bruce.richardson@intel.com>
>
> When including the rte_ether.h header in applications with warnings
> enabled, a warning was given because of the assumption of 2-byte alignment
> of ethernet addresses when processing them.
>
> .../include/rte_ether.h:149:2: warning: converting a packed ‘const
> struct ether_addr’ pointer (alignment 1) to a ‘unaligned_uint16_t’
> {aka ‘const short unsigned int’} pointer (alignment 2) may result in
> an unaligned pointer value [-Waddress-of-packed-member]
> 149 | const unaligned_uint16_t *ea_words = (const unaligned_uint16_t *)ea;
> | ^~~~~
>
> Since ethernet addresses should always be aligned on a two-byte boundary,
> we can just inform the compiler of this assumption to remove the warnings
> and allow us to always access the addresses using 16-bit operations.
>
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
@@ -58,7 +58,8 @@ extern "C" {
* See http://standards.ieee.org/regauth/groupmac/tutorial.html
*/
struct rte_ether_addr {
- uint8_t addr_bytes[RTE_ETHER_ADDR_LEN]; /**< Addr bytes in tx order */
+ uint8_t addr_bytes[RTE_ETHER_ADDR_LEN] __rte_aligned(2);
+ /**< Addr bytes in tx order */
} __attribute__((__packed__));
#define RTE_ETHER_LOCAL_ADMIN_ADDR 0x02 /**< Locally assigned Eth. address. */
@@ -81,8 +82,8 @@ struct rte_ether_addr {
static inline int rte_is_same_ether_addr(const struct rte_ether_addr *ea1,
const struct rte_ether_addr *ea2)
{
- const unaligned_uint16_t *w1 = (const uint16_t *)ea1;
- const unaligned_uint16_t *w2 = (const uint16_t *)ea2;
+ const uint16_t *w1 = (const uint16_t *)ea1;
+ const uint16_t *w2 = (const uint16_t *)ea2;
return ((w1[0] ^ w2[0]) | (w1[1] ^ w2[1]) | (w1[2] ^ w2[2])) == 0;
}
@@ -99,7 +100,7 @@ static inline int rte_is_same_ether_addr(const struct rte_ether_addr *ea1,
*/
static inline int rte_is_zero_ether_addr(const struct rte_ether_addr *ea)
{
- const unaligned_uint16_t *w = (const uint16_t *)ea;
+ const uint16_t *w = (const uint16_t *)ea;
return (w[0] | w[1] | w[2]) == 0;
}
@@ -146,7 +147,7 @@ static inline int rte_is_multicast_ether_addr(const struct rte_ether_addr *ea)
*/
static inline int rte_is_broadcast_ether_addr(const struct rte_ether_addr *ea)
{
- const unaligned_uint16_t *ea_words = (const unaligned_uint16_t *)ea;
+ const uint16_t *ea_words = (const uint16_t *)ea;
return (ea_words[0] == 0xFFFF && ea_words[1] == 0xFFFF &&
ea_words[2] == 0xFFFF);