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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/vppinfra/bihash_template.h
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/vppinfra/bihash_template.h')
-rw-r--r--src/vppinfra/bihash_template.h12
1 files changed, 10 insertions, 2 deletions
diff --git a/src/vppinfra/bihash_template.h b/src/vppinfra/bihash_template.h
index c4e120e4a1f..e8a2c01cece 100644
--- a/src/vppinfra/bihash_template.h
+++ b/src/vppinfra/bihash_template.h
@@ -410,6 +410,7 @@ BV (clib_bihash_get_bucket) (BVT (clib_bihash) * h, u64 hash)
static inline int BV (clib_bihash_search_inline_with_hash)
(BVT (clib_bihash) * h, u64 hash, BVT (clib_bihash_kv) * key_result)
{
+ BVT (clib_bihash_kv) rv;
BVT (clib_bihash_value) * v;
BVT (clib_bihash_bucket) * b;
int i, limit;
@@ -455,7 +456,10 @@ static inline int BV (clib_bihash_search_inline_with_hash)
{
if (BV (clib_bihash_key_compare) (v->kvp[i].key, key_result->key))
{
- *key_result = v->kvp[i];
+ rv = v->kvp[i];
+ if (BV (clib_bihash_is_free) (&rv))
+ return -1;
+ *key_result = rv;
return 0;
}
}
@@ -509,6 +513,7 @@ static inline int BV (clib_bihash_search_inline_2_with_hash)
(BVT (clib_bihash) * h,
u64 hash, BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep)
{
+ BVT (clib_bihash_kv) rv;
BVT (clib_bihash_value) * v;
BVT (clib_bihash_bucket) * b;
int i, limit;
@@ -556,7 +561,10 @@ static inline int BV (clib_bihash_search_inline_2_with_hash)
{
if (BV (clib_bihash_key_compare) (v->kvp[i].key, search_key->key))
{
- *valuep = v->kvp[i];
+ rv = v->kvp[i];
+ if (BV (clib_bihash_is_free) (&rv))
+ return -1;
+ *valuep = rv;
return 0;
}
}