[PATCH v3] mbuf: deprecate GCC marker in rte mbuf struct
Tyler Retzlaff
roretzla at linux.microsoft.com
Wed Feb 14 00:33:29 CET 2024
Provide a macro that allows conditional expansion of RTE_MARKER fields
to empty to allow rte_mbuf to be used with MSVC. It is proposed that
we announce the fields to be __rte_deprecated (currently disabled).
Introduce C11 anonymous unions to permit aliasing of well-known
offsets by name into the rte_mbuf structure by a *new* name and to
provide padding for cache alignment.
Signed-off-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
---
lib/eal/include/rte_common.h | 6 +
lib/mbuf/rte_mbuf_core.h | 365 +++++++++++++++++++++++--------------------
2 files changed, 201 insertions(+), 170 deletions(-)
diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index d7d6390..af73f67 100644
--- a/lib/eal/include/rte_common.h
+++ b/lib/eal/include/rte_common.h
@@ -582,6 +582,12 @@ static void __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
/** Marker for 8B alignment in a structure. */
__extension__ typedef uint64_t RTE_MARKER64[0];
+#define __rte_marker(type, name) type name /* __rte_deprecated */
+
+#else
+
+#define __rte_marker(type, name)
+
#endif
/*********** Macros for calculating min and max **********/
diff --git a/lib/mbuf/rte_mbuf_core.h b/lib/mbuf/rte_mbuf_core.h
index 5688683..fd02353 100644
--- a/lib/mbuf/rte_mbuf_core.h
+++ b/lib/mbuf/rte_mbuf_core.h
@@ -16,7 +16,10 @@
* New fields and flags should fit in the "dynamic space".
*/
+#include <assert.h>
+#include <stdalign.h>
#include <stdint.h>
+#include <stddef.h>
#include <rte_byteorder.h>
#include <rte_stdatomic.h>
@@ -464,206 +467,228 @@ enum {
* The generic rte_mbuf, containing a packet mbuf.
*/
struct rte_mbuf {
- RTE_MARKER cacheline0;
-
- void *buf_addr; /**< Virtual address of segment buffer. */
+ __rte_marker(RTE_MARKER, cacheline0);
+ union {
+ char mbuf_cacheline0[RTE_CACHE_LINE_MIN_SIZE];
+ struct {
+ void *buf_addr; /**< Virtual address of segment buffer. */
#if RTE_IOVA_IN_MBUF
- /**
- * Physical address of segment buffer.
- * This field is undefined if the build is configured to use only
- * virtual address as IOVA (i.e. RTE_IOVA_IN_MBUF is 0).
- * Force alignment to 8-bytes, so as to ensure we have the exact
- * same mbuf cacheline0 layout for 32-bit and 64-bit. This makes
- * working on vector drivers easier.
- */
- rte_iova_t buf_iova __rte_aligned(sizeof(rte_iova_t));
+ /**
+ * Physical address of segment buffer.
+ * This field is undefined if the build is configured to use only
+ * virtual address as IOVA (i.e. RTE_IOVA_IN_MBUF is 0).
+ * Force alignment to 8-bytes, so as to ensure we have the exact
+ * same mbuf cacheline0 layout for 32-bit and 64-bit. This makes
+ * working on vector drivers easier.
+ */
+ rte_iova_t buf_iova __rte_aligned(sizeof(rte_iova_t));
#else
- /**
- * Next segment of scattered packet.
- * This field is valid when physical address field is undefined.
- * Otherwise next pointer in the second cache line will be used.
- */
- struct rte_mbuf *next;
+ /**
+ * Next segment of scattered packet.
+ * This field is valid when physical address field is undefined.
+ * Otherwise next pointer in the second cache line will be used.
+ */
+ struct rte_mbuf *next;
#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;
-
- /**
- * 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;
-
- uint64_t ol_flags; /**< Offload features. */
+ /* next 8 bytes are initialised on RX descriptor rearm */
+ __rte_marker(RTE_MARKER64, rearm_data);
+ union {
+ char mbuf_rearm_data[8];
+ 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;
+
+ /** 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;
+ };
+ };
- /* remaining bytes are set on RX when pulling packet from descriptor */
- RTE_MARKER rx_descriptor_fields1;
+ uint64_t ol_flags; /**< Offload features. */
- /*
- * 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. */
- __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. */
+ /* remaining bytes are set on RX when pulling packet from descriptor */
+ __rte_marker(RTE_MARKER, rx_descriptor_fields1);
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__
+ char mbuf_rx_descriptor_fields1[sizeof(void *)];
struct {
- uint8_t inner_l2_type:4;
- /**< Inner L2 type. */
- uint8_t inner_l3_type:4;
- /**< Inner L3 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 {
+ uint32_t packet_type; /**< L2/L3/L4 and tunnel information. */
+ __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. */
+ 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. */
+ };
+ };
+ uint32_t pkt_len; /**< Total pkt len: sum of all segments. */
};
};
- 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;
+ 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 {
+ 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. */
+ struct rte_mempool *pool; /**< Pool from which mbuf was allocated. */
+ };
+ };
/* second cache line - fields only used in slow path or on TX */
- RTE_MARKER cacheline1 __rte_cache_min_aligned;
-
-#if RTE_IOVA_IN_MBUF
- /**
- * Next segment of scattered packet. Must be NULL in the last
- * segment or in case of non-segmented packet.
- */
- struct rte_mbuf *next;
-#else
- /**
- * Reserved for dynamic fields
- * when the next pointer is in first cache line (i.e. RTE_IOVA_IN_MBUF is 0).
- */
- uint64_t dynfield2;
-#endif
-
- /* fields to support TX offloads */
+ __rte_marker(RTE_MARKER, cacheline1);
union {
- uint64_t tx_offload; /**< combined for easy fetch */
- __extension__
+ char mbuf_cacheline1[RTE_CACHE_LINE_MIN_SIZE];
struct {
- uint64_t l2_len:RTE_MBUF_L2_LEN_BITS;
- /**< L2 (MAC) Header Length for non-tunneling pkt.
- * Outer_L4_len + ... + Inner_L2_len for tunneling pkt.
+#if RTE_IOVA_IN_MBUF
+ /**
+ * Next segment of scattered packet. Must be NULL in the last
+ * segment or in case of non-segmented packet.
*/
- uint64_t l3_len:RTE_MBUF_L3_LEN_BITS;
- /**< L3 (IP) Header Length. */
- uint64_t l4_len:RTE_MBUF_L4_LEN_BITS;
- /**< L4 (TCP/UDP) Header Length. */
- uint64_t tso_segsz:RTE_MBUF_TSO_SEGSZ_BITS;
- /**< TCP TSO segment size */
-
- /*
- * Fields for Tx offloading of tunnels.
- * These are undefined for packets which don't request
- * any tunnel offloads (outer IP or UDP checksum,
- * tunnel TSO).
- *
- * PMDs should not use these fields unconditionally
- * when calculating offsets.
- *
- * Applications are expected to set appropriate tunnel
- * offload flags when they fill in these fields.
+ struct rte_mbuf *next;
+#else
+ /**
+ * Reserved for dynamic fields
+ * when the next pointer is in first cache line (i.e. RTE_IOVA_IN_MBUF is 0).
*/
- uint64_t outer_l3_len:RTE_MBUF_OUTL3_LEN_BITS;
- /**< Outer L3 (IP) Hdr Length. */
- uint64_t outer_l2_len:RTE_MBUF_OUTL2_LEN_BITS;
- /**< Outer L2 (MAC) Hdr Length. */
+ uint64_t dynfield2;
+#endif
- /* uint64_t unused:RTE_MBUF_TXOFLD_UNUSED_BITS; */
- };
- };
+ /* fields to support TX offloads */
+ union {
+ uint64_t tx_offload; /**< combined for easy fetch */
+ __extension__
+ struct {
+ uint64_t l2_len:RTE_MBUF_L2_LEN_BITS;
+ /**< L2 (MAC) Header Length for non-tunneling pkt.
+ * Outer_L4_len + ... + Inner_L2_len for tunneling pkt.
+ */
+ uint64_t l3_len:RTE_MBUF_L3_LEN_BITS;
+ /**< L3 (IP) Header Length. */
+ uint64_t l4_len:RTE_MBUF_L4_LEN_BITS;
+ /**< L4 (TCP/UDP) Header Length. */
+ uint64_t tso_segsz:RTE_MBUF_TSO_SEGSZ_BITS;
+ /**< TCP TSO segment size */
+
+ /*
+ * Fields for Tx offloading of tunnels.
+ * These are undefined for packets which don't request
+ * any tunnel offloads (outer IP or UDP checksum,
+ * tunnel TSO).
+ *
+ * PMDs should not use these fields unconditionally
+ * when calculating offsets.
+ *
+ * Applications are expected to set appropriate tunnel
+ * offload flags when they fill in these fields.
+ */
+ uint64_t outer_l3_len:RTE_MBUF_OUTL3_LEN_BITS;
+ /**< Outer L3 (IP) Hdr Length. */
+ uint64_t outer_l2_len:RTE_MBUF_OUTL2_LEN_BITS;
+ /**< Outer L2 (MAC) Hdr Length. */
+
+ /* uint64_t unused:RTE_MBUF_TXOFLD_UNUSED_BITS; */
+ };
+ };
- /** Shared data for external buffer attached to mbuf. See
- * rte_pktmbuf_attach_extbuf().
- */
- struct rte_mbuf_ext_shared_info *shinfo;
+ /** Shared data for external buffer attached to mbuf. See
+ * rte_pktmbuf_attach_extbuf().
+ */
+ struct rte_mbuf_ext_shared_info *shinfo;
- /** Size of the application private data. In case of an indirect
- * mbuf, it stores the direct mbuf private data size.
- */
- uint16_t priv_size;
+ /** Size of the application private data. In case of an indirect
+ * mbuf, it stores the direct mbuf private data size.
+ */
+ uint16_t priv_size;
- /** Timesync flags for use with IEEE1588. */
- uint16_t timesync;
+ /** Timesync flags for use with IEEE1588. */
+ uint16_t timesync;
- uint32_t dynfield1[9]; /**< Reserved for dynamic fields. */
+ uint32_t dynfield1[9]; /**< Reserved for dynamic fields. */
+ };
+ };
} __rte_cache_aligned;
+static_assert(alignof(struct rte_mbuf) == RTE_CACHE_LINE_SIZE, "alignof rte_mbuf");
+static_assert(offsetof(struct rte_mbuf, cacheline0) == 0, "cacheline0");
+static_assert(offsetof(struct rte_mbuf, cacheline1) == RTE_CACHE_LINE_MIN_SIZE, "cacheline1");
+static_assert(sizeof(struct rte_mbuf) == RTE_CACHE_LINE_MIN_SIZE * 2, "sizeof rte_mbuf");
+
/**
* Function typedef of callback to free externally attached buffer.
*/
--
1.8.3.1
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