[dpdk-dev] [PATCH v2 1/3] mempool: fix mempool virt populate with small chunks

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

To populate a mempool with a virtual area, the mempool code calls
rte_mempool_populate_iova() for each iova-contiguous area. It happens
(rarely) that this area is too small to store one object. In this case,
rte_mempool_populate_iova() returns an error, which is forwarded by
rte_mempool_populate_virt().

This case should not throw an error in
rte_mempool_populate_virt(). Instead, the area that is too small should
just be ignored.

To fix this issue, change the return value of
rte_mempool_populate_iova() to 0 when no object can be populated,
so it can be ignored by the caller. As this would be an API/ABI change,
only do this modification internally for now.

Fixes: 354788b60cfd ("mempool: allow populating with unaligned virtual area")
Cc: stable@dpdk.org

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Tested-by: Anatoly Burakov <anatoly.burakov@intel.com>
Tested-by: Zhang Alvin <alvinx.zhang@intel.com>
---
 lib/librte_mempool/rte_mempool.c | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index f8d453d21..b434d9f17 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -297,8 +297,8 @@ mempool_ops_alloc_once(struct rte_mempool *mp)
  * zone. Return the number of objects added, or a negative value
  * on error.
  */
-int
-rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
+static 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)
 {
@@ -332,7 +332,7 @@ rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 		off = RTE_PTR_ALIGN_CEIL(vaddr, RTE_MEMPOOL_ALIGN) - vaddr;
 
 	if (off > len) {
-		ret = -EINVAL;
+		ret = 0;
 		goto fail;
 	}
 
@@ -343,7 +343,7 @@ rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 
 	/* not enough room to store one object */
 	if (i == 0) {
-		ret = -EINVAL;
+		ret = 0;
 		goto fail;
 	}
 
@@ -356,6 +356,21 @@ rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
 	return ret;
 }
 
+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)
+{
+	int ret;
+
+	ret = __rte_mempool_populate_iova(mp, vaddr, iova, len, free_cb,
+					opaque);
+	if (ret == 0)
+		ret = -EINVAL;
+
+	return ret;
+}
+
 static rte_iova_t
 get_iova(void *addr)
 {
@@ -406,8 +421,10 @@ 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(mp, addr + off, iova,
 			phys_len, free_cb, opaque);
+		if (ret == 0)
+			continue;
 		if (ret < 0)
 			goto fail;
 		/* no need to call the free callback for next chunks */
@@ -415,6 +432,9 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
 		cnt += ret;
 	}
 
+	if (cnt == 0)
+		return -EINVAL;
+
 	return cnt;
 
  fail:
-- 
2.20.1