[dpdk-dev] [PATCH v4] eal: fix create user mem map repeatedly when it exists

[wangyunjian]

From: Yunjian Wang <wangyunjian at huawei.com>

Currently, user mem maps will check if the newly mapped area is adjacent
to any existing mapping, but will not check if the mapping is identical
because it assumes that the API will never get called with the same
mapping twice. This will result in duplicate entries in the user mem
maps list.

Fix it by also checking for duplicate mappings, and skipping them if
they are found.

Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
Cc: stable at dpdk.org

Signed-off-by: Yunjian Wang <wangyunjian at huawei.com>
Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
v4:
  Update commit log suggested by Anatoly Burakov
---
 lib/librte_eal/linux/eal_vfio.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/librte_eal/linux/eal_vfio.c b/lib/librte_eal/linux/eal_vfio.c
index 050082444e..0967215783 100644
--- a/lib/librte_eal/linux/eal_vfio.c
+++ b/lib/librte_eal/linux/eal_vfio.c
@@ -168,6 +168,10 @@ adjust_map(struct user_mem_map *src, struct user_mem_map *end,
 static int
 merge_map(struct user_mem_map *left, struct user_mem_map *right)
 {
+	/* merge the same maps into one */
+	if (memcmp(left, right, sizeof(struct user_mem_map)) == 0)
+		goto out;
+
 	if (left->addr + left->len != right->addr)
 		return 0;
 	if (left->iova + left->len != right->iova)
@@ -175,6 +179,7 @@ merge_map(struct user_mem_map *left, struct user_mem_map *right)
 
 	left->len += right->len;
 
+out:
 	memset(right, 0, sizeof(*right));
 
 	return 1;
-- 
2.23.0