[dpdk-dev] [PATCH] lib/lpm:fix two issues in the delete_depth_small()

[Jijiang Liu <jijiang.liu@intel.com>]

Fix two issues in the delete_depth_small() function.
 
1> The control is not strict in this function.
 
In the following structure,
struct rte_lpm_tbl24_entry {
        union {
                uint8_t next_hop;
                uint8_t tbl8_gindex;
        };
     uint8_t ext_entry :1;
}
 
When ext_entry = 0, use next_hop.only to process rte_lpm_tbl24_entry.
 
When ext_entry = 1, use tbl8_gindex to process the rte_lpm_tbl8_entry.
 
When using LPM24 + 8 algorithm, it will use ext_entry to decide to process rte_lpm_tbl24_entry structure or rte_lpm_tbl8_entry structure. 
If a route is deleted, the prefix of previous route is used to override the deleted route. when (lpm->tbl24[i].ext_entry == 0 && lpm->tbl24[i].depth > depth) 
it should be ignored, but due to the incorrect logic, the next_hop is used as tbl8_gindex and will process the rte_lpm_tbl8_entry.
 
2> Initialization of rte_lpm_tbl8_entry is incorrect in this function 
 
In this function, use new rte_lpm_tbl8_entry we call A to replace the old rte_lpm_tbl8_entry. But the valid_group do not set VALID, so it will be INVALID.
Then when adding a new route which depth is > 24,the tbl8_alloc() function will search the rte_lpm_tbl8_entrys to find INVALID valid_group, 
and it will return the A to the add_depth_big function, so A's data is overridden.

Signed-off-by: NaNa <nana.nn@alibaba-inc.com>

---
 lib/librte_lpm/rte_lpm.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c
index 163ba3c..3981452 100644
--- a/lib/librte_lpm/rte_lpm.c
+++ b/lib/librte_lpm/rte_lpm.c
@@ -734,8 +734,7 @@ delete_depth_small(struct rte_lpm *lpm, uint32_t ip_masked,
 			if (lpm->tbl24[i].ext_entry == 0 &&
 					lpm->tbl24[i].depth <= depth ) {
 				lpm->tbl24[i].valid = INVALID;
-			}
-			else {
+			} else if (lpm->tbl24[i].ext_entry == 1) {
 				/*
 				 * If TBL24 entry is extended, then there has
 				 * to be a rule with depth >= 25 in the
@@ -770,6 +769,7 @@ delete_depth_small(struct rte_lpm *lpm, uint32_t ip_masked,
 
 		struct rte_lpm_tbl8_entry new_tbl8_entry = {
 			.valid = VALID,
+			.valid_group = VALID,
 			.depth = sub_rule_depth,
 			.next_hop = lpm->rules_tbl
 			[sub_rule_index].next_hop,
@@ -780,8 +780,7 @@ delete_depth_small(struct rte_lpm *lpm, uint32_t ip_masked,
 			if (lpm->tbl24[i].ext_entry == 0 &&
 					lpm->tbl24[i].depth <= depth ) {
 				lpm->tbl24[i] = new_tbl24_entry;
-			}
-			else {
+			} else  if (lpm->tbl24[i].ext_entry == 1) {
 				/*
 				 * If TBL24 entry is extended, then there has
 				 * to be a rule with depth >= 25 in the
-- 
1.7.7.6