RE: [RFC] ethdev: convert string initialization

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Ferruh Yigit [mailto:ferruh.yigit@amd.com]
> Sent: Thursday, 1 August 2024 11.27
> 
> gcc 15 experimental [1], with -Wextra flag, gives warning in variable
> initialization as string [2].
> 
> The warning has a point when initialized variable is intended to use as
> string, since assignment is missing the required null terminator for
> this case. But warning is useless for our usecase.
> 
> I don't know if this behaviour will change in gcc15, as it is still
> under development. But if not we may need to update our initialization.
> 
> In this patch only updated a few instance to show the issue, there are
> many instances to fix, if we prefer to go this way.
> Other option is to disable warning but it can be useful for actual
> string usecases, so I prefer to keep it.

Compiler warnings are here to help, so +1 for fixing the code.

> 
> [1]
> gcc (GCC) 15.0.0 20240801 (experimental)
> 
> [2]
> ../lib/ethdev/rte_flow.h:906:36:
>   error: initializer-string for array of ‘unsigned char’ is too long
>         [-Werror=unterminated-string-initialization]
> 906 |         .hdr.dst_addr.addr_bytes = "\xff\xff\xff\xff\xff\xff",
>     |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ../lib/ethdev/rte_flow.h:907:36:
>   error: initializer-string for array of ‘unsigned char’ is too long
>          [-Werror=unterminated-string-initialization]
> 907 |         .hdr.src_addr.addr_bytes = "\xff\xff\xff\xff\xff\xff",
>     |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ../lib/ethdev/rte_flow.h:1009:25:
>   error: initializer-string for array of ‘unsigned char’ is too long
>          [-Werror=unterminated-string-initialization]
> 1009 |                         "\xff\xff\xff\xff\xff\xff\xff\xff"
>      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ../lib/ethdev/rte_flow.h:1012:25:
>   error: initializer-string for array of ‘unsigned char’ is too long
>          [-Werror=unterminated-string-initialization]
> 1012 |                         "\xff\xff\xff\xff\xff\xff\xff\xff"
>      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ../lib/ethdev/rte_flow.h:1135:20:
>   error: initializer-string for array of ‘unsigned char’ is too long
>          [-Werror=unterminated-string-initialization]
> 1135 |         .hdr.vni = "\xff\xff\xff",
>      |                    ^~~~~~~~~~~~~~
> 
> Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> ---
>  lib/ethdev/rte_flow.h | 16 +++++++---------
>  1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h
> index f864578f806b..8b623974cd44 100644
> --- a/lib/ethdev/rte_flow.h
> +++ b/lib/ethdev/rte_flow.h
> @@ -903,8 +903,8 @@ struct rte_flow_item_eth {
>  /** Default mask for RTE_FLOW_ITEM_TYPE_ETH. */
>  #ifndef __cplusplus
>  static const struct rte_flow_item_eth rte_flow_item_eth_mask = {
> -	.hdr.dst_addr.addr_bytes = "\xff\xff\xff\xff\xff\xff",
> -	.hdr.src_addr.addr_bytes = "\xff\xff\xff\xff\xff\xff",
> +	.hdr.dst_addr.addr_bytes = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
> +	.hdr.src_addr.addr_bytes = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },

Please define and use an RTE_ETHER_ADDR() macro like RTE_IPV4() [1]:

/** Create Ethernet address */
#define RTE_ETHER_ADDR(a, b, c, d, e, f) \
	(struct rte_ether_addr){{a, b, c, d, e, f}}

Or even better, also add and use an RTE_ETHER_ADDR_BROADCAST definition like RTE_IPV4_BROADCAST [2]:

#define RTE_ETHER_ADDR_BROADCAST RTE_ETHER_ADDR(0xff, 0xff, 0xff, 0xff, 0xff, 0xff)

Then the above code could become:
+	.hdr.dst_addr = RTE_ETHER_ADDR_BROADCAST,
+	.hdr.src_addr = RTE_ETHER_ADDR_BROADCAST,

On the other hand, if they are address masks, maybe using RTE_ETHER_ADDR(0xff, 0xff, 0xff, 0xff, 0xff, 0xff) would be more appropriate.

[1]: https://elixir.bootlin.com/dpdk/v24.07/source/lib/net/rte_ip.h#L67
[2]: https://elixir.bootlin.com/dpdk/v24.07/source/lib/net/rte_ip.h#L111

>  	.hdr.ether_type = RTE_BE16(0x0000),
>  };
>  #endif
> @@ -1005,12 +1005,10 @@ struct rte_flow_item_ipv6 {
>  #ifndef __cplusplus
>  static const struct rte_flow_item_ipv6 rte_flow_item_ipv6_mask = {
>  	.hdr = {
> -		.src_addr =
> -			"\xff\xff\xff\xff\xff\xff\xff\xff"
> -			"\xff\xff\xff\xff\xff\xff\xff\xff",
> -		.dst_addr =
> -			"\xff\xff\xff\xff\xff\xff\xff\xff"
> -			"\xff\xff\xff\xff\xff\xff\xff\xff",
> +		.src_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
> 0xff,
> +			      0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
> },
> +		.dst_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
> 0xff,
> +			      0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
> },

Please define and use an RTE_IPV6() macro like RTE_IPV4() [1].
Or even better, add and use an RTE_IPV6_BROADCAST definition like RTE_IPV4_BROADCAST [2].

(Same comment about maybe using RTE_IPV6() instead of RTE_IPV6_BROADCAST for masks being more appropriate.)

Note: Robin is working on a series to introduce an IPv6 address type [3], so you should coordinate the definition of the IPV6 macros/definitions with him.

[3]: https://inbox.dpdk.org/dev/98CBD80474FA8B44BF855DF32C47DC35E9F5B1@smartserver.smartshare.dk/

>  	},
>  };
>  #endif
> @@ -1132,7 +1130,7 @@ struct rte_flow_item_vxlan {
>  /** Default mask for RTE_FLOW_ITEM_TYPE_VXLAN. */
>  #ifndef __cplusplus
>  static const struct rte_flow_item_vxlan rte_flow_item_vxlan_mask = {
> -	.hdr.vni = "\xff\xff\xff",
> +	.hdr.vni = { 0xff, 0xff, 0xff },

Yes you your suggestion here. (No special type/macro required.)

>  };
>  #endif
> 
> --
> 2.43.0

With suggested changes,

Acked-by: Morten Brørup <mb@smartsharesystems.com>