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authorDave Barach <dave@barachs.net>2023-03-16 13:03:47 -0400
committerFlorin Coras <florin.coras@gmail.com>2023-03-18 18:35:46 +0000
commitb9c8c57e983246ec034bc9059b1740558c951d51 (patch)
treecd7267591894b30cea54522fb53ffa1deca1f450 /src/plugins
parent04bd0ea8e22dac53c09e3867cabf6256d19477fa (diff)
vppinfra: fix corner-cases in bihash lookup
In a case where one pounds on a single kvp in a KVP_AT_BUCKET_LEVEL table, the code would sporadically return a transitional value (junk) from a half-deleted kvp. At most, 64-bits worth of the kvp will be written atomically, so using memset(...) to smear 0xFF's across a kvp to free it left a lot to be desired. Performance impact: very mild positive, thanks to FC for doing a multi-thread host stack perf/scale test. Added an ASSERT to catch attempts to add a (key,value) pair which contains the magic "free kvp" value. Type: fix Signed-off-by: Dave Barach <dave@barachs.net> Change-Id: I6a1aa8a2c30bc70bec4b696ce7b17c2839927065
Diffstat (limited to 'src/plugins')
-rw-r--r--src/plugins/cnat/cnat_bihash.h9
-rw-r--r--src/plugins/cnat/cnat_session.c2
2 files changed, 8 insertions, 3 deletions
diff --git a/src/plugins/cnat/cnat_bihash.h b/src/plugins/cnat/cnat_bihash.h
index c488e61a07d..75099f6bfdb 100644
--- a/src/plugins/cnat/cnat_bihash.h
+++ b/src/plugins/cnat/cnat_bihash.h
@@ -44,11 +44,16 @@ typedef struct
u64 value[7];
} clib_bihash_kv_40_56_t;
+static inline void
+clib_bihash_mark_free_40_56 (clib_bihash_kv_40_56_t *v)
+{
+ v->value[0] = 0xFEEDFACE8BADF00DULL;
+}
+
static inline int
clib_bihash_is_free_40_56 (const clib_bihash_kv_40_56_t *v)
{
- /* Free values are clib_memset to 0xff, check a bit... */
- if (v->key[0] == ~0ULL && v->value[0] == ~0ULL)
+ if (v->value[0] == 0xFEEDFACE8BADF00DULL)
return 1;
return 0;
}
diff --git a/src/plugins/cnat/cnat_session.c b/src/plugins/cnat/cnat_session.c
index fa04de602b4..ea34d913217 100644
--- a/src/plugins/cnat/cnat_session.c
+++ b/src/plugins/cnat/cnat_session.c
@@ -238,7 +238,7 @@ cnat_session_scan (vlib_main_t * vm, f64 start_time, int i)
{
for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
{
- if (v->kvp[k].key[0] == ~0ULL && v->kvp[k].value[0] == ~0ULL)
+ if (BV (clib_bihash_is_free) (&v->kvp[k]))
continue;
cnat_session_t *session = (cnat_session_t *) & v->kvp[k];