[dpdk-stable] [dpdk-dev] [PATCH v2] eal/linux: do not create user mem map repeatedly when it exists

[wangyunjian]

From: Yunjian Wang <wangyunjian at huawei.com>

Currently, we will create new user mem map entry for the same memory
segment, but in fact it has already been added to the user mem maps.
It's not necessary to create it twice.

To resolve the issue, add support to remove the same entry in the
function compact_user_maps().

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

Signed-off-by: Yunjian Wang <wangyunjian at huawei.com>
---
v2:
* Remove the same entry in the function compact_user_maps()
---
 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 abb12a354..df99307b7 100644
--- a/lib/librte_eal/linux/eal_vfio.c
+++ b/lib/librte_eal/linux/eal_vfio.c
@@ -167,6 +167,10 @@ 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)
@@ -174,6 +178,7 @@ 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