[dpdk-dev] [RFC] mbuf: remove control mbuf

[Olivier Matz <olivier.matz@6wind.com>]

The rte_ctrlmbuf structure is not used by any example application
in dpdk. Remove it, as announced on the mailing list.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---

This RFC targets 18.05.
If no opposition, I'll send a deprecation notice for it.


 doc/guides/prog_guide/glossary.rst   |  3 --
 doc/guides/prog_guide/mbuf_lib.rst   | 11 +++--
 doc/guides/prog_guide/overview.rst   |  4 +-
 doc/guides/prog_guide/source_org.rst |  2 +-
 lib/librte_mbuf/Makefile             |  2 +-
 lib/librte_mbuf/rte_mbuf.c           | 15 -------
 lib/librte_mbuf/rte_mbuf.h           | 86 ------------------------------------
 lib/librte_mbuf/rte_mbuf_version.map |  1 -
 8 files changed, 9 insertions(+), 115 deletions(-)

diff --git a/doc/guides/prog_guide/glossary.rst b/doc/guides/prog_guide/glossary.rst
index 4cbed4c60..a49319423 100644
--- a/doc/guides/prog_guide/glossary.rst
+++ b/doc/guides/prog_guide/glossary.rst
@@ -68,9 +68,6 @@ CPU
 CRC
    Cyclic Redundancy Check
 
-ctrlmbuf
-   An *mbuf* carrying control data.
-
 Data Plane
    In contrast to the control plane, the data plane in a network architecture
    are the layers involved when forwarding packets.  These layers must be
diff --git a/doc/guides/prog_guide/mbuf_lib.rst b/doc/guides/prog_guide/mbuf_lib.rst
index 6e73fc5a8..b82f88764 100644
--- a/doc/guides/prog_guide/mbuf_lib.rst
+++ b/doc/guides/prog_guide/mbuf_lib.rst
@@ -37,9 +37,8 @@ The mbuf library provides the ability to allocate and free buffers (mbufs)
 that may be used by the DPDK application to store message buffers.
 The message buffers are stored in a mempool, using the :ref:`Mempool Library <Mempool_Library>`.
 
-A rte_mbuf struct can carry network packet buffers
-or generic control buffers (indicated by the CTRL_MBUF_FLAG).
-This can be extended to other types.
+A rte_mbuf struct generally carries network packet buffers, but it can actually
+be any data (control data, events, ...).
 The rte_mbuf header structure is kept as small as possible and currently uses
 just two cache lines, with the most frequently used fields being on the first
 of the two cache lines.
@@ -95,13 +94,13 @@ Buffers Stored in Memory Pools
 The Buffer Manager uses the :ref:`Mempool Library <Mempool_Library>` to allocate buffers.
 Therefore, it ensures that the packet header is interleaved optimally across the channels and ranks for L3 processing.
 An mbuf contains a field indicating the pool that it originated from.
-When calling rte_ctrlmbuf_free(m) or rte_pktmbuf_free(m), the mbuf returns to its original pool.
+When calling rte_pktmbuf_free(m), the mbuf returns to its original pool.
 
 Constructors
 ------------
 
-Packet and control mbuf constructors are provided by the API.
-The rte_pktmbuf_init() and rte_ctrlmbuf_init() functions initialize some fields in the mbuf structure that
+Packet mbuf constructors are provided by the API.
+The rte_pktmbuf_init() function initializes some fields in the mbuf structure that
 are not modified by the user once created (mbuf type, origin pool, buffer start address, and so on).
 This function is given as a callback function to the rte_mempool_create() function at pool creation time.
 
diff --git a/doc/guides/prog_guide/overview.rst b/doc/guides/prog_guide/overview.rst
index 9986e3cbc..af411fd3b 100644
--- a/doc/guides/prog_guide/overview.rst
+++ b/doc/guides/prog_guide/overview.rst
@@ -157,8 +157,8 @@ The mbuf library provides the facility to create and destroy buffers
 that may be used by the DPDK application to store message buffers.
 The message buffers are created at startup time and stored in a mempool, using the DPDK mempool library.
 
-This library provides an API to allocate/free mbufs, manipulate control message buffers (ctrlmbuf) which are generic message buffers,
-and packet buffers (pktmbuf) which are used to carry network packets.
+This library provides an API to allocate/free mbufs, manipulate
+packet buffers which are used to carry network packets.
 
 Network Packet Buffer Management is described in :ref:`Mbuf Library <Mbuf_Library>`.
 
diff --git a/doc/guides/prog_guide/source_org.rst b/doc/guides/prog_guide/source_org.rst
index 7aab4b45e..06c9d8fe9 100644
--- a/doc/guides/prog_guide/source_org.rst
+++ b/doc/guides/prog_guide/source_org.rst
@@ -73,7 +73,7 @@ The lib directory contains::
     +-- librte_kni          # Kernel NIC interface
     +-- librte_kvargs       # Argument parsing library
     +-- librte_lpm          # Longest prefix match library
-    +-- librte_mbuf         # Packet and control mbuf manipulation
+    +-- librte_mbuf         # Packet buffer manipulation
     +-- librte_mempool      # Memory pool manager (fixed sized objects)
     +-- librte_meter        # QoS metering library
     +-- librte_net          # Various IP-related headers
diff --git a/lib/librte_mbuf/Makefile b/lib/librte_mbuf/Makefile
index f6be35366..aa879a13e 100644
--- a/lib/librte_mbuf/Makefile
+++ b/lib/librte_mbuf/Makefile
@@ -39,7 +39,7 @@ LDLIBS += -lrte_eal -lrte_mempool
 
 EXPORT_MAP := rte_mbuf_version.map
 
-LIBABIVER := 3
+LIBABIVER := 4
 
 # all source are stored in SRCS-y
 SRCS-$(CONFIG_RTE_LIBRTE_MBUF) := rte_mbuf.c rte_mbuf_ptype.c
diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 7543662f7..2f0dec1e3 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -60,21 +60,6 @@
 #include <rte_memcpy.h>
 
 /*
- * ctrlmbuf constructor, given as a callback function to
- * rte_mempool_obj_iter() or rte_mempool_create()
- */
-void
-rte_ctrlmbuf_init(struct rte_mempool *mp,
-		__attribute__((unused)) void *opaque_arg,
-		void *_m,
-		__attribute__((unused)) unsigned i)
-{
-	struct rte_mbuf *m = _m;
-	rte_pktmbuf_init(mp, opaque_arg, _m, i);
-	m->ol_flags |= CTRL_MBUF_FLAG;
-}
-
-/*
  * pktmbuf pool constructor, given as a callback function to
  * rte_mempool_create(), or called directly if using
  * rte_mempool_create_empty()/rte_mempool_populate()
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index dd08cb72b..2c48ef9ae 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -343,9 +343,6 @@ extern "C" {
 
 #define IND_ATTACHED_MBUF    (1ULL << 62) /**< Indirect attached mbuf */
 
-/* Use final bit of flags to indicate a control mbuf */
-#define CTRL_MBUF_FLAG       (1ULL << 63) /**< Mbuf contains control data */
-
 /** Alignment constraint of mbuf private area. */
 #define RTE_MBUF_PRIV_ALIGN 8
 
@@ -930,89 +927,6 @@ __rte_mbuf_raw_free(struct rte_mbuf *m)
 	rte_mbuf_raw_free(m);
 }
 
-/* Operations on ctrl mbuf */
-
-/**
- * The control mbuf constructor.
- *
- * This function initializes some fields in an mbuf structure that are
- * not modified by the user once created (mbuf type, origin pool, buffer
- * start address, and so on). This function is given as a callback function
- * to rte_mempool_obj_iter() or rte_mempool_create() at pool creation time.
- *
- * @param mp
- *   The mempool from which the mbuf is allocated.
- * @param opaque_arg
- *   A pointer that can be used by the user to retrieve useful information
- *   for mbuf initialization. This pointer is the opaque argument passed to
- *   rte_mempool_obj_iter() or rte_mempool_create().
- * @param m
- *   The mbuf to initialize.
- * @param i
- *   The index of the mbuf in the pool table.
- */
-void rte_ctrlmbuf_init(struct rte_mempool *mp, void *opaque_arg,
-		void *m, unsigned i);
-
-/**
- * Allocate a new mbuf (type is ctrl) from mempool *mp*.
- *
- * This new mbuf is initialized with data pointing to the beginning of
- * buffer, and with a length of zero.
- *
- * @param mp
- *   The mempool from which the mbuf is allocated.
- * @return
- *   - The pointer to the new mbuf on success.
- *   - NULL if allocation failed.
- */
-#define rte_ctrlmbuf_alloc(mp) rte_pktmbuf_alloc(mp)
-
-/**
- * Free a control mbuf back into its original mempool.
- *
- * @param m
- *   The control mbuf to be freed.
- */
-#define rte_ctrlmbuf_free(m) rte_pktmbuf_free(m)
-
-/**
- * A macro that returns the pointer to the carried data.
- *
- * The value that can be read or assigned.
- *
- * @param m
- *   The control mbuf.
- */
-#define rte_ctrlmbuf_data(m) ((char *)((m)->buf_addr) + (m)->data_off)
-
-/**
- * A macro that returns the length of the carried data.
- *
- * The value that can be read or assigned.
- *
- * @param m
- *   The control mbuf.
- */
-#define rte_ctrlmbuf_len(m) rte_pktmbuf_data_len(m)
-
-/**
- * Tests if an mbuf is a control mbuf
- *
- * @param m
- *   The mbuf to be tested
- * @return
- *   - True (1) if the mbuf is a control mbuf
- *   - False(0) otherwise
- */
-static inline int
-rte_is_ctrlmbuf(struct rte_mbuf *m)
-{
-	return !!(m->ol_flags & CTRL_MBUF_FLAG);
-}
-
-/* Operations on pkt mbuf */
-
 /**
  * The packet mbuf constructor.
  *
diff --git a/lib/librte_mbuf/rte_mbuf_version.map b/lib/librte_mbuf/rte_mbuf_version.map
index 6e2ea8456..43bed8c95 100644
--- a/lib/librte_mbuf/rte_mbuf_version.map
+++ b/lib/librte_mbuf/rte_mbuf_version.map
@@ -1,7 +1,6 @@
 DPDK_2.0 {
 	global:
 
-	rte_ctrlmbuf_init;
 	rte_get_rx_ol_flag_name;
 	rte_get_tx_ol_flag_name;
 	rte_mbuf_sanity_check;
-- 
2.11.0