Re: [RFC] ethdev: convert string initialization

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 8/1/2024 12:29 PM, Morten Brørup wrote:
>> 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.
> 

Hi Morten,

These are all masks used for flow API, and as mentioned in the commit
log there are bunch of them, not just the ones in the patch, I am not
sure about creating a macro for each is necessary.


> [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>
>