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

[Ori Kam]

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.

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