[PATCH v7 2/4] mbuf: remove rte marker fields

[Tyler Retzlaff]

RTE_MARKER typedefs are a GCC extension unsupported by MSVC. Remove
RTE_MARKER fields from rte_mbuf struct.

Maintain alignment of fields after removed cacheline1 marker by placing
C11 alignas(RTE_CACHE_LINE_MIN_SIZE).

Provide new rearm_data and rx_descriptor_fields1 fields in anonymous
unions as single element arrays of with types matching the original
markers to maintain API compatibility.

Signed-off-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
---
 doc/guides/rel_notes/release_24_03.rst |   2 +
 lib/mbuf/rte_mbuf.h                    |   4 +-
 lib/mbuf/rte_mbuf_core.h               | 188 ++++++++++++++++++---------------
 3 files changed, 104 insertions(+), 90 deletions(-)

diff --git a/doc/guides/rel_notes/release_24_03.rst b/doc/guides/rel_notes/release_24_03.rst
index 14826ea..4f18cca 100644
--- a/doc/guides/rel_notes/release_24_03.rst
+++ b/doc/guides/rel_notes/release_24_03.rst
@@ -216,6 +216,8 @@ Removed Items
 
 * acc101: Removed obsolete code for non productized HW variant.
 
+* mbuf: ``RTE_MARKER`` fields ``cacheline0`` and ``cacheline1``
+  have been removed from ``struct rte_mbuf``.
 
 API Changes
 -----------
diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h
index 286b32b..4c4722e 100644
--- a/lib/mbuf/rte_mbuf.h
+++ b/lib/mbuf/rte_mbuf.h
@@ -108,7 +108,7 @@
 static inline void
 rte_mbuf_prefetch_part1(struct rte_mbuf *m)
 {
-	rte_prefetch0(&m->cacheline0);
+	rte_prefetch0(m);
 }
 
 /**
@@ -126,7 +126,7 @@
 rte_mbuf_prefetch_part2(struct rte_mbuf *m)
 {
 #if RTE_CACHE_LINE_SIZE == 64
-	rte_prefetch0(&m->cacheline1);
+	rte_prefetch0(RTE_PTR_ADD(m, RTE_CACHE_LINE_MIN_SIZE));
 #else
 	RTE_SET_USED(m);
 #endif
diff --git a/lib/mbuf/rte_mbuf_core.h b/lib/mbuf/rte_mbuf_core.h
index 9f58076..665213c 100644
--- a/lib/mbuf/rte_mbuf_core.h
+++ b/lib/mbuf/rte_mbuf_core.h
@@ -465,8 +465,6 @@ enum {
  * The generic rte_mbuf, containing a packet mbuf.
  */
 struct __rte_cache_aligned rte_mbuf {
-	RTE_MARKER cacheline0;
-
 	void *buf_addr;           /**< Virtual address of segment buffer. */
 #if RTE_IOVA_IN_MBUF
 	/**
@@ -488,116 +486,130 @@ struct __rte_cache_aligned rte_mbuf {
 #endif
 
 	/* next 8 bytes are initialised on RX descriptor rearm */
-	RTE_MARKER64 rearm_data;
-	uint16_t data_off;
-
-	/**
-	 * Reference counter. Its size should at least equal to the size
-	 * of port field (16 bits), to support zero-copy broadcast.
-	 * It should only be accessed using the following functions:
-	 * rte_mbuf_refcnt_update(), rte_mbuf_refcnt_read(), and
-	 * rte_mbuf_refcnt_set(). The functionality of these functions (atomic,
-	 * or non-atomic) is controlled by the RTE_MBUF_REFCNT_ATOMIC flag.
-	 */
-	RTE_ATOMIC(uint16_t) refcnt;
+	union {
+		uint64_t rearm_data[1];
+		__extension__
+		struct {
+			uint16_t data_off;
+
+			/**
+			 * Reference counter. Its size should at least equal to the size
+			 * of port field (16 bits), to support zero-copy broadcast.
+			 * It should only be accessed using the following functions:
+			 * rte_mbuf_refcnt_update(), rte_mbuf_refcnt_read(), and
+			 * rte_mbuf_refcnt_set(). The functionality of these functions (atomic,
+			 * or non-atomic) is controlled by the RTE_MBUF_REFCNT_ATOMIC flag.
+			 */
+			RTE_ATOMIC(uint16_t) refcnt;
 
-	/**
-	 * Number of segments. Only valid for the first segment of an mbuf
-	 * chain.
-	 */
-	uint16_t nb_segs;
+			/**
+			 * Number of segments. Only valid for the first segment of an mbuf
+			 * chain.
+			 */
+			uint16_t nb_segs;
 
-	/** Input port (16 bits to support more than 256 virtual ports).
-	 * The event eth Tx adapter uses this field to specify the output port.
-	 */
-	uint16_t port;
+			/** Input port (16 bits to support more than 256 virtual ports).
+			 * The event eth Tx adapter uses this field to specify the output port.
+			 */
+			uint16_t port;
+		};
+	};
 
 	uint64_t ol_flags;        /**< Offload features. */
 
 	/* remaining bytes are set on RX when pulling packet from descriptor */
-	RTE_MARKER rx_descriptor_fields1;
-
-	/*
-	 * The packet type, which is the combination of outer/inner L2, L3, L4
-	 * and tunnel types. The packet_type is about data really present in the
-	 * mbuf. Example: if vlan stripping is enabled, a received vlan packet
-	 * would have RTE_PTYPE_L2_ETHER and not RTE_PTYPE_L2_VLAN because the
-	 * vlan is stripped from the data.
-	 */
 	union {
-		uint32_t packet_type; /**< L2/L3/L4 and tunnel information. */
+		void *rx_descriptor_fields1[1];
 		__extension__
 		struct {
-			uint8_t l2_type:4;   /**< (Outer) L2 type. */
-			uint8_t l3_type:4;   /**< (Outer) L3 type. */
-			uint8_t l4_type:4;   /**< (Outer) L4 type. */
-			uint8_t tun_type:4;  /**< Tunnel type. */
+			/*
+			 * The packet type, which is the combination of outer/inner L2, L3, L4
+			 * and tunnel types. The packet_type is about data really present in the
+			 * mbuf. Example: if vlan stripping is enabled, a received vlan packet
+			 * would have RTE_PTYPE_L2_ETHER and not RTE_PTYPE_L2_VLAN because the
+			 * vlan is stripped from the data.
+			 */
 			union {
-				uint8_t inner_esp_next_proto;
-				/**< ESP next protocol type, valid if
-				 * RTE_PTYPE_TUNNEL_ESP tunnel type is set
-				 * on both Tx and Rx.
-				 */
+				uint32_t packet_type; /**< L2/L3/L4 and tunnel information. */
 				__extension__
 				struct {
-					uint8_t inner_l2_type:4;
-					/**< Inner L2 type. */
-					uint8_t inner_l3_type:4;
-					/**< Inner L3 type. */
+					uint8_t l2_type:4;   /**< (Outer) L2 type. */
+					uint8_t l3_type:4;   /**< (Outer) L3 type. */
+					uint8_t l4_type:4;   /**< (Outer) L4 type. */
+					uint8_t tun_type:4;  /**< Tunnel type. */
+					union {
+						uint8_t inner_esp_next_proto;
+						/**< ESP next protocol type, valid if
+						 * RTE_PTYPE_TUNNEL_ESP tunnel type is set
+						 * on both Tx and Rx.
+						 */
+						__extension__
+						struct {
+							uint8_t inner_l2_type:4;
+							/**< Inner L2 type. */
+							uint8_t inner_l3_type:4;
+							/**< Inner L3 type. */
+						};
+					};
+					uint8_t inner_l4_type:4; /**< Inner L4 type. */
 				};
 			};
-			uint8_t inner_l4_type:4; /**< Inner L4 type. */
-		};
-	};
 
-	uint32_t pkt_len;         /**< Total pkt len: sum of all segments. */
-	uint16_t data_len;        /**< Amount of data in segment buffer. */
-	/** VLAN TCI (CPU order), valid if RTE_MBUF_F_RX_VLAN is set. */
-	uint16_t vlan_tci;
+			/*
+			 * pkt_len is not actually part of rx_descriptor_fields1
+			 * but is included here to account for changes in alignment
+			 * and offset for void * on 32-bit vs 64-bit targets.
+			 */
+			uint32_t pkt_len;         /**< Total pkt len: sum of all segments. */
 
-	union {
-		union {
-			uint32_t rss;     /**< RSS hash result if RSS enabled */
-			struct {
+			uint16_t data_len;        /**< Amount of data in segment buffer. */
+			/** VLAN TCI (CPU order), valid if RTE_MBUF_F_RX_VLAN is set. */
+			uint16_t vlan_tci;
+
+			union {
 				union {
+					uint32_t rss;     /**< RSS hash result if RSS enabled */
 					struct {
-						uint16_t hash;
-						uint16_t id;
-					};
-					uint32_t lo;
-					/**< Second 4 flexible bytes */
-				};
-				uint32_t hi;
-				/**< First 4 flexible bytes or FD ID, dependent
-				 * on RTE_MBUF_F_RX_FDIR_* flag in ol_flags.
-				 */
-			} fdir;	/**< Filter identifier if FDIR enabled */
-			struct rte_mbuf_sched sched;
-			/**< Hierarchical scheduler : 8 bytes */
-			struct {
-				uint32_t reserved1;
-				uint16_t reserved2;
-				uint16_t txq;
-				/**< The event eth Tx adapter uses this field
-				 * to store Tx queue id.
-				 * @see rte_event_eth_tx_adapter_txq_set()
-				 */
-			} txadapter; /**< Eventdev ethdev Tx adapter */
-			uint32_t usr;
-			/**< User defined tags. See rte_distributor_process() */
-		} hash;                   /**< hash information */
-	};
+						union {
+							struct {
+								uint16_t hash;
+								uint16_t id;
+							};
+							uint32_t lo;
+							/**< Second 4 flexible bytes */
+						};
+						uint32_t hi;
+						/**< First 4 flexible bytes or FD ID, dependent
+						 * on RTE_MBUF_F_RX_FDIR_* flag in ol_flags.
+						 */
+					} fdir;	/**< Filter identifier if FDIR enabled */
+					struct rte_mbuf_sched sched;
+					/**< Hierarchical scheduler : 8 bytes */
+					struct {
+						uint32_t reserved1;
+						uint16_t reserved2;
+						uint16_t txq;
+						/**< The event eth Tx adapter uses this field
+						 * to store Tx queue id.
+						 * @see rte_event_eth_tx_adapter_txq_set()
+						 */
+					} txadapter; /**< Eventdev ethdev Tx adapter */
+					uint32_t usr;
+					/**< User defined tags. See rte_distributor_process() */
+				} hash;                   /**< hash information */
+			};
 
-	/** Outer VLAN TCI (CPU order), valid if RTE_MBUF_F_RX_QINQ is set. */
-	uint16_t vlan_tci_outer;
+			/** Outer VLAN TCI (CPU order), valid if RTE_MBUF_F_RX_QINQ is set. */
+			uint16_t vlan_tci_outer;
 
-	uint16_t buf_len;         /**< Length of segment buffer. */
+			uint16_t buf_len;         /**< Length of segment buffer. */
+		};
+	};
 
 	struct rte_mempool *pool; /**< Pool from which mbuf was allocated. */
 
 	/* second cache line - fields only used in slow path or on TX */
-	alignas(RTE_CACHE_LINE_MIN_SIZE) RTE_MARKER cacheline1;
-
+	alignas(RTE_CACHE_LINE_MIN_SIZE)
 #if RTE_IOVA_IN_MBUF
 	/**
 	 * Next segment of scattered packet. Must be NULL in the last
-- 
1.8.3.1