[PATCH v3 2/3] ethdev: add compare item

[Ferruh Yigit]

On 1/31/2024 3:56 PM, Ori Kam wrote:
> Hi
> 
>> -----Original Message-----
>> From: Suanming Mou <suanmingm at nvidia.com>
>> Sent: Wednesday, January 31, 2024 4:48 AM
>>
>> Hi,
>>
>>> -----Original Message-----
>>> From: Ferruh Yigit <ferruh.yigit at amd.com>
>>> Sent: Wednesday, January 31, 2024 1:34 AM
>>> To: Suanming Mou <suanmingm at nvidia.com>; Ori Kam
>> <orika at nvidia.com>;
>>> Aman Singh <aman.deep.singh at intel.com>; Yuying Zhang
>>> <yuying.zhang at intel.com>; NBU-Contact-Thomas Monjalon (EXTERNAL)
>>> <thomas at monjalon.net>; Andrew Rybchenko
>>> <andrew.rybchenko at oktetlabs.ru>
>>> Cc: dev at dpdk.org
>>> Subject: Re: [PATCH v3 2/3] ethdev: add compare item
>>>
>>> On 1/15/2024 9:13 AM, Suanming Mou wrote:
>>>> The new item type is added for the case user wants to match traffic
>>>> based on packet field compare result with other fields or immediate
>>>> value.
>>>>
>>>> e.g. take advantage the compare item user will be able to accumulate a
>>>> IPv4/TCP packet's TCP data_offset and IPv4 IHL field to a tag
>>>> register, then compare the tag register with IPv4 header total length
>>>> to understand the packet has payload or not.
>>>>
>>>
>>> ack, above sample makes it easier to understand.
>>>
>>> This patch is adding testpmd commands, can you please provide some
>> sample
>>> commands in commit log?
>>> The more samples are better, as far as I remember there was a testpmd
>>> documentation that documents the sample usages, can you please check
>> for it?
> 
> [Snip ..]
> 
>>>
>>>> +/**
>>>> + * @warning
>>>> + * @b EXPERIMENTAL: this structure may change without prior notice
>>>> + *
>>>> + * Field description for packet field.
>>>> + */
>>>> +struct rte_flow_field_data {
>>>> +	enum rte_flow_field_id field; /**< Field or memory type ID. */
>>>> +	union {
>>>> +		struct {
>>>> +			/** Encapsulation level and tag index or flex item
>>> handle. */
>>>> +			union {
>>>> +				struct {
>>>> +					/**
>>>> +					 * Packet encapsulation level
>> containing
>>>> +					 * the field to modify.
>>>> +					 *
>>>> +					 * - @p 0 requests the default
>> behavior.
>>>> +					 *   Depending on the packet type, it
>>>> +					 *   can mean outermost, innermost
>> or
>>>> +					 *   anything in between.
>>>> +					 *
>>>> +					 *   It basically stands for the
>>>> +					 *   innermost encapsulation level.
>>>> +					 *   Modification can be performed
>>>> +					 *   according to PMD and device
>>>> +					 *   capabilities.
>>>> +					 *
>>>> +					 * - @p 1 requests modification to be
>>>> +					 *   performed on the outermost
>> packet
>>>> +					 *   encapsulation level.
>>>> +					 *
>>>> +					 * - @p 2 and subsequent values
>>> request
>>>> +					 *   modification to be performed on
>>>> +					 *   the specified inner packet
>>>> +					 *   encapsulation level, from
>>>> +					 *   outermost to innermost (lower to
>>>> +					 *   higher values).
>>>> +					 *
>>>> +					 * Values other than @p 0 are not
>>>> +					 * necessarily supported.
>>>> +					 *
>>>> +					 * @note that for MPLS field,
>>>> +					 * encapsulation level also include
>>>> +					 * tunnel since MPLS may appear in
>>>> +					 * outer, inner or tunnel.
>>>> +					 */
>>>> +					uint8_t level;
>>>> +					union {
>>>> +						/**
>>>> +						 * Tag index array inside
>>>> +						 * encapsulation level.
>>>> +						 * Used for VLAN, MPLS or
>> TAG
>>> types.
>>>> +						 */
>>>> +						uint8_t tag_index;
>>>> +						/**
>>>> +						 * Geneve option identifier.
>>>> +						 * Relevant only for
>>>> +						 *
>>> RTE_FLOW_FIELD_GENEVE_OPT_XXXX
>>>> +						 * modification type.
>>>> +						 */
>>>> +						struct {
>>>> +							/**
>>>> +							 * Geneve option
>> type.
>>>> +							 */
>>>> +							uint8_t type;
>>>> +							/**
>>>> +							 * Geneve option
>> class.
>>>> +							 */
>>>> +							rte_be16_t class_id;
>>>> +						};
>>>> +					};
>>>> +				};
>>>> +				struct rte_flow_item_flex_handle
>> *flex_handle;
>>>> +			};
>>>> +			/** Number of bits to skip from a field. */
>>>> +			uint32_t offset;
>>>> +		};
>>>> +		/**
>>>> +		 * Immediate value for RTE_FLOW_FIELD_VALUE, presented
>> in
>>> the
>>>> +		 * same byte order and length as in relevant
>> rte_flow_item_xxx.
>>>> +		 * The immediate source bitfield offset is inherited from
>>>> +		 * the destination's one.
>>>> +		 */
>>>> +		uint8_t value[16];
>>>> +		/**
>>>> +		 * Memory address for RTE_FLOW_FIELD_POINTER, memory
>>> layout
>>>> +		 * should be the same as for relevant field in the
>>>> +		 * rte_flow_item_xxx structure.
>>>> +		 */
>>>> +		void *pvalue;
>>>> +	};
>>>> +};
>>>> +
>>>>
>>>
>>> I am aware that you are just moving the above struct, but it is nested too
>> much
>>> which is making it hard to read.
>>>
>>> As you are touching it, can we extract some structs and make this struct less
>>> nested, what do you think?
>>> Of course it needs to be done in separate patch, as a preperation/clean-up
>> patch
>>> before moving it around.
>>
>> Agree the struct maybe a bit nested. But not sure how it was discussed
>> before during the last new member was added... @Ori, Do you have any idea
>> about this?
>>
> 
> As far as I remember, it was never discussed, 
> 
> I think for this series we should keep it as is, and revise it later.
> 

If you don't want to make this set more complex with this, that is OK as
long as it is addressed at some point.

> Best,
> Ori
>> And if it is really expected, I believe another new thread is worth for that
>> change,  better not be in that series.
>> Need to discuss the new struct name and other stuff. What do you think?
>>
>>>
>>> <...>
>>>
>>>> +/**
>>>> + *
>>>> + * RTE_FLOW_ITEM_TYPE_COMPARE
>>>> + *
>>>> + * Matches the packet with compare result.
>>>> + *
>>>> + * The operation means a compare with b result.
>>>> + */
>>>> +struct rte_flow_item_compare {
>>>> +	enum rte_flow_item_compare_op operation; /* The compare
>> operation.
>>> */
>>>> +	struct rte_flow_field_data a;		 /* Field be compared.  */
>>>> +	struct rte_flow_field_data b;		 /* Field as comparator. */
>>>>
>>>
>>> Variable names 'a' and 'b' are not descriptive although it may be OK since
>> there is
>>> no significance to the values, but other option can be 'first' and 'second',
>> but
>>> overall not strong opinion.
>>
>> Yes, thanks for the suggestion, in fact we also discussed about the name a lot,
>> finally we choose the widely used 'a' and 'b'
>>
>> Thanks
>