[dpdk-dev] [PATCH v5] mempool: return 0 if area is too small on populate

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

Change rte_mempool_populate_iova() and rte_mempool_populate_virt() to
return 0 instead of -EINVAL when there is not enough room to store one
object, as it can be helpful for applications to distinguish this
specific case.

As this is an ABI change, use symbol versioning to preserve old
behavior for binary applications.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---

changes in v5:
    - fix version: 20.0.2 -> 21
    - fix commit log: populate_iova -> populate_virt

changes in v4:
    - move populate_iova trace in v20_0_2 base function

changes in v3:
    - rebase
    - remove deprecation notice
    - notify API change in release notes
    - fix ABI version from 20.0.1 to 20.0.2 (should be 21 maybe)


 doc/guides/rel_notes/deprecation.rst       |  5 --
 doc/guides/rel_notes/release_20_05.rst     |  4 ++
 examples/ntb/ntb_fwd.c                     |  2 +-
 lib/librte_mempool/meson.build             |  2 +
 lib/librte_mempool/rte_mempool.c           | 80 ++++++++++++++++++----
 lib/librte_mempool/rte_mempool.h           | 14 ++--
 lib/librte_mempool/rte_mempool_version.map |  7 ++
 7 files changed, 92 insertions(+), 22 deletions(-)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 1339f54f5..20aa745b7 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -65,11 +65,6 @@ Deprecation Notices
   structure would be made internal (or removed if all dependencies are cleared)
   in future releases.
 
-* mempool: starting from v20.05, the API of rte_mempool_populate_iova()
-  and rte_mempool_populate_virt() will change to return 0 instead
-  of -EINVAL when there is not enough room to store one object. The ABI
-  will be preserved until 20.11.
-
 * ethdev: the legacy filter API, including
   ``rte_eth_dev_filter_supported()``, ``rte_eth_dev_filter_ctrl()`` as well
   as filter types MACVLAN, ETHERTYPE, FLEXIBLE, SYN, NTUPLE, TUNNEL, FDIR,
diff --git a/doc/guides/rel_notes/release_20_05.rst b/doc/guides/rel_notes/release_20_05.rst
index b124c3f28..ab20a7d02 100644
--- a/doc/guides/rel_notes/release_20_05.rst
+++ b/doc/guides/rel_notes/release_20_05.rst
@@ -241,6 +241,10 @@ API Changes
    Also, make sure to start the actual text at the margin.
    =========================================================
 
+* mempool: The API of ``rte_mempool_populate_iova()`` and
+  ``rte_mempool_populate_virt()`` changed to return 0 instead of -EINVAL
+  when there is not enough room to store one object.
+
 
 ABI Changes
 -----------
diff --git a/examples/ntb/ntb_fwd.c b/examples/ntb/ntb_fwd.c
index d49189e17..eba8ebf9f 100644
--- a/examples/ntb/ntb_fwd.c
+++ b/examples/ntb/ntb_fwd.c
@@ -1319,7 +1319,7 @@ ntb_mbuf_pool_create(uint16_t mbuf_seg_size, uint32_t nb_mbuf,
 					mz->len - ntb_info.ntb_hdr_size,
 					ntb_mempool_mz_free,
 					(void *)(uintptr_t)mz);
-		if (ret < 0) {
+		if (ret <= 0) {
 			rte_memzone_free(mz);
 			rte_mempool_free(mp);
 			return NULL;
diff --git a/lib/librte_mempool/meson.build b/lib/librte_mempool/meson.build
index a6e861cbf..7dbe6b9be 100644
--- a/lib/librte_mempool/meson.build
+++ b/lib/librte_mempool/meson.build
@@ -9,6 +9,8 @@ foreach flag: extra_flags
 	endif
 endforeach
 
+use_function_versioning = true
+
 sources = files('rte_mempool.c', 'rte_mempool_ops.c',
 		'rte_mempool_ops_default.c', 'mempool_trace_points.c')
 headers = files('rte_mempool.h', 'rte_mempool_trace.h',
diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 0be8f9f59..0bde995b5 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -31,6 +31,7 @@
 #include <rte_string_fns.h>
 #include <rte_spinlock.h>
 #include <rte_tailq.h>
+#include <rte_function_versioning.h>
 
 #include "rte_mempool.h"
 #include "rte_mempool_trace.h"
@@ -303,12 +304,17 @@ mempool_ops_alloc_once(struct rte_mempool *mp)
 	return 0;
 }
 
+__vsym int
+rte_mempool_populate_iova_v21(struct rte_mempool *mp, char *vaddr,
+	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
+	void *opaque);
+
 /* Add objects in the pool, using a physically contiguous memory
  * zone. Return the number of objects added, or a negative value
  * on error.
  */
-static int
-__rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
+__vsym int
+rte_mempool_populate_iova_v21(struct rte_mempool *mp, char *vaddr,
 	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
 	void *opaque)
 {
@@ -359,6 +365,8 @@ __rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 
 	STAILQ_INSERT_TAIL(&mp->mem_list, memhdr, next);
 	mp->nb_mem_chunks++;
+
+	rte_mempool_trace_populate_iova(mp, vaddr, iova, len, free_cb, opaque);
 	return i;
 
 fail:
@@ -366,21 +374,34 @@ __rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 	return ret;
 }
 
-int
-rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
+BIND_DEFAULT_SYMBOL(rte_mempool_populate_iova, _v21, 21);
+MAP_STATIC_SYMBOL(
+	int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
+				rte_iova_t iova, size_t len,
+				rte_mempool_memchunk_free_cb_t *free_cb,
+				void *opaque),
+	rte_mempool_populate_iova_v21);
+
+__vsym int
+rte_mempool_populate_iova_v20(struct rte_mempool *mp, char *vaddr,
+	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
+	void *opaque);
+
+__vsym int
+rte_mempool_populate_iova_v20(struct rte_mempool *mp, char *vaddr,
 	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
 	void *opaque)
 {
 	int ret;
 
-	ret = __rte_mempool_populate_iova(mp, vaddr, iova, len, free_cb,
+	ret = rte_mempool_populate_iova_v21(mp, vaddr, iova, len, free_cb,
 					opaque);
 	if (ret == 0)
 		ret = -EINVAL;
 
-	rte_mempool_trace_populate_iova(mp, vaddr, iova, len, free_cb, opaque);
 	return ret;
 }
+VERSION_SYMBOL(rte_mempool_populate_iova, _v20, 20.0);
 
 static rte_iova_t
 get_iova(void *addr)
@@ -395,11 +416,16 @@ get_iova(void *addr)
 	return ms->iova + RTE_PTR_DIFF(addr, ms->addr);
 }
 
+__vsym int
+rte_mempool_populate_virt_v21(struct rte_mempool *mp, char *addr,
+	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
+	void *opaque);
+
 /* Populate the mempool with a virtual area. Return the number of
  * objects added, or a negative value on error.
  */
-int
-rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
+__vsym int
+rte_mempool_populate_virt_v21(struct rte_mempool *mp, char *addr,
 	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
 	void *opaque)
 {
@@ -432,7 +458,7 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
 				break;
 		}
 
-		ret = __rte_mempool_populate_iova(mp, addr + off, iova,
+		ret = rte_mempool_populate_iova_v21(mp, addr + off, iova,
 			phys_len, free_cb, opaque);
 		if (ret == 0)
 			continue;
@@ -443,9 +469,6 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
 		cnt += ret;
 	}
 
-	if (cnt == 0)
-		return -EINVAL;
-
 	rte_mempool_trace_populate_virt(mp, addr, len, pg_sz, free_cb, opaque);
 	return cnt;
 
@@ -453,6 +476,35 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
 	rte_mempool_free_memchunks(mp);
 	return ret;
 }
+BIND_DEFAULT_SYMBOL(rte_mempool_populate_virt, _v21, 21);
+MAP_STATIC_SYMBOL(
+	int rte_mempool_populate_virt(struct rte_mempool *mp,
+				char *addr, size_t len, size_t pg_sz,
+				rte_mempool_memchunk_free_cb_t *free_cb,
+				void *opaque),
+	rte_mempool_populate_virt_v21);
+
+__vsym int
+rte_mempool_populate_virt_v20(struct rte_mempool *mp, char *addr,
+	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
+	void *opaque);
+
+__vsym int
+rte_mempool_populate_virt_v20(struct rte_mempool *mp, char *addr,
+	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
+	void *opaque)
+{
+	int ret;
+
+	ret = rte_mempool_populate_virt_v21(mp, addr, len, pg_sz,
+						free_cb, opaque);
+
+	if (ret == 0)
+		ret = -EINVAL;
+
+	return ret;
+}
+VERSION_SYMBOL(rte_mempool_populate_virt, _v20, 20.0);
 
 /* Get the minimal page size used in a mempool before populating it. */
 int
@@ -609,6 +661,8 @@ rte_mempool_populate_default(struct rte_mempool *mp)
 				mz->len, pg_sz,
 				rte_mempool_memchunk_mz_free,
 				(void *)(uintptr_t)mz);
+		if (ret == 0) /* should not happen */
+			ret = -ENOBUFS;
 		if (ret < 0) {
 			rte_memzone_free(mz);
 			goto fail;
@@ -701,6 +755,8 @@ rte_mempool_populate_anon(struct rte_mempool *mp)
 
 	ret = rte_mempool_populate_virt(mp, addr, size, getpagesize(),
 		rte_mempool_memchunk_anon_free, addr);
+	if (ret == 0) /* should not happen */
+		ret = -ENOBUFS;
 	if (ret < 0) {
 		rte_errno = -ret;
 		goto fail;
diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
index 6e0573ea4..652d19f9f 100644
--- a/lib/librte_mempool/rte_mempool.h
+++ b/lib/librte_mempool/rte_mempool.h
@@ -1112,9 +1112,12 @@ rte_mempool_free(struct rte_mempool *mp);
  * @param opaque
  *   An opaque argument passed to free_cb.
  * @return
- *   The number of objects added on success.
+ *   The number of objects added on success (strictly positive).
  *   On error, the chunk is not added in the memory list of the
- *   mempool and a negative errno is returned.
+ *   mempool the following code is returned:
+ *     (0): not enough room in chunk for one object.
+ *     (-ENOSPC): mempool is already populated.
+ *     (-ENOMEM): allocation failure.
  */
 int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
@@ -1139,9 +1142,12 @@ int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
  * @param opaque
  *   An opaque argument passed to free_cb.
  * @return
- *   The number of objects added on success.
+ *   The number of objects added on success (strictly positive).
  *   On error, the chunk is not added in the memory list of the
- *   mempool and a negative errno is returned.
+ *   mempool the following code is returned:
+ *     (0): not enough room in chunk for one object.
+ *     (-ENOSPC): mempool is already populated.
+ *     (-ENOMEM): allocation failure.
  */
 int
 rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
diff --git a/lib/librte_mempool/rte_mempool_version.map b/lib/librte_mempool/rte_mempool_version.map
index 695dd6e04..826a0b882 100644
--- a/lib/librte_mempool/rte_mempool_version.map
+++ b/lib/librte_mempool/rte_mempool_version.map
@@ -31,6 +31,13 @@ DPDK_20.0 {
 	local: *;
 };
 
+DPDK_21 {
+	global:
+
+	rte_mempool_populate_iova;
+	rte_mempool_populate_virt;
+} DPDK_20.0;
+
 EXPERIMENTAL {
 	global:
 
-- 
2.25.1