From b9c8c57e983246ec034bc9059b1740558c951d51 Mon Sep 17 00:00:00 2001 From: Dave Barach Date: Thu, 16 Mar 2023 13:03:47 -0400 Subject: 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 Change-Id: I6a1aa8a2c30bc70bec4b696ce7b17c2839927065 --- src/plugins/cnat/cnat_bihash.h | 9 +++++++-- src/plugins/cnat/cnat_session.c | 2 +- 2 files changed, 8 insertions(+), 3 deletions(-) (limited to 'src/plugins/cnat') 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]; -- cgit 1.2.3-korg