vppinfra: Fix bihash coverity warning

[vpp.git] / src / vppinfra / bihash_template.h

diff --git a/src/vppinfra/bihash_template.h b/src/vppinfra/bihash_template.h
index b8e0a23..d6aa3c9 100644 (file)
--- a/src/vppinfra/bihash_template.h
+++ b/src/vppinfra/bihash_template.h
@@ -260,21 +260,19 @@ static inline void BV (clib_bihash_alloc_unlock) (BVT (clib_bihash) * h)
 
 static inline void BV (clib_bihash_lock_bucket) (BVT (clib_bihash_bucket) * b)
 {
-  BVT (clib_bihash_bucket) unlocked_bucket, locked_bucket;
+  /* *INDENT-OFF* */
+  BVT (clib_bihash_bucket) mask = { .lock = 1 };
+  /* *INDENT-ON* */
+  u64 old;
 
-  locked_bucket.as_u64 = unlocked_bucket.as_u64 = b->as_u64;
-  unlocked_bucket.lock = 0;
-  locked_bucket.lock = 1;
+try_again:
+  old = clib_atomic_fetch_or (&b->as_u64, mask.as_u64);
 
-  while (__atomic_compare_exchange_n (&b->as_u64, &unlocked_bucket.as_u64,
-                                     locked_bucket.as_u64, 1 /* weak */ ,
-                                     __ATOMIC_ACQUIRE,
-                                     __ATOMIC_ACQUIRE) == 0)
+  if (PREDICT_FALSE (old & mask.as_u64))
     {
+      /* somebody else flipped the bit, try again */
       CLIB_PAUSE ();
-      locked_bucket.as_u64 = unlocked_bucket.as_u64 = b->as_u64;
-      unlocked_bucket.lock = 0;
-      locked_bucket.lock = 1;
+      goto try_again;
     }
 }
 
@@ -320,9 +318,9 @@ void BV (clib_bihash_init)
 void BV (clib_bihash_init2) (BVT (clib_bihash_init2_args) * a);
 
 #if BIHASH_32_64_SVM
-void BV (clib_bihash_master_init_svm)
+void BV (clib_bihash_initiator_init_svm)
   (BVT (clib_bihash) * h, char *name, u32 nbuckets, u64 memory_size);
-void BV (clib_bihash_slave_init_svm)
+void BV (clib_bihash_responder_init_svm)
   (BVT (clib_bihash) * h, char *name, int fd);
 #endif
 
@@ -370,9 +368,9 @@ BV (clib_bihash_get_bucket) (BVT (clib_bihash) * h, u64 hash)
   offset = offset * (sizeof (BVT (clib_bihash_bucket))
                     + (BIHASH_KVP_PER_PAGE * sizeof (BVT (clib_bihash_kv))));
   return ((BVT (clib_bihash_bucket) *) (((u8 *) h->buckets) + offset));
-#endif
-
+#else
   return h->buckets + (hash & (h->nbuckets - 1));
+#endif
 }
 
 static inline int BV (clib_bihash_search_inline_with_hash)
@@ -382,8 +380,15 @@ static inline int BV (clib_bihash_search_inline_with_hash)
   BVT (clib_bihash_bucket) * b;
   int i, limit;
 
+  /* *INDENT-OFF* */
+  static const BVT (clib_bihash_bucket) mask = {
+    .linear_search = 1,
+    .log2_pages = -1
+  };
+  /* *INDENT-ON* */
+
 #if BIHASH_LAZY_INSTANTIATE
-  if (PREDICT_FALSE (alloc_arena (h) == 0))
+  if (PREDICT_FALSE (h->instantiated == 0))
     return -1;
 #endif
 
@@ -399,15 +404,18 @@ static inline int BV (clib_bihash_search_inline_with_hash)
        CLIB_PAUSE ();
     }
 
-  hash >>= h->log2_nbuckets;
-
   v = BV (clib_bihash_get_value) (h, b->offset);
 
   /* If the bucket has unresolvable collisions, use linear search */
   limit = BIHASH_KVP_PER_PAGE;
-  v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0;
-  if (PREDICT_FALSE (b->linear_search))
-    limit <<= b->log2_pages;
+
+  if (PREDICT_FALSE (b->as_u64 & mask.as_u64))
+    {
+      if (PREDICT_FALSE (b->linear_search))
+       limit <<= b->log2_pages;
+      else
+       v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
+    }
 
   for (i = 0; i < limit; i++)
     {
@@ -445,7 +453,7 @@ static inline void BV (clib_bihash_prefetch_data)
   BVT (clib_bihash_bucket) * b;
 
 #if BIHASH_LAZY_INSTANTIATE
-  if (PREDICT_FALSE (alloc_arena (h) == 0))
+  if (PREDICT_FALSE (h->instantiated == 0))
     return;
 #endif
 
@@ -454,12 +462,13 @@ static inline void BV (clib_bihash_prefetch_data)
   if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
     return;
 
-  hash >>= h->log2_nbuckets;
   v = BV (clib_bihash_get_value) (h, b->offset);
 
-  v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0;
+  if (PREDICT_FALSE (b->log2_pages && b->linear_search == 0))
+    v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
 
-  clib_prefetch_load (v);
+  CLIB_PREFETCH (v, BIHASH_KVP_PER_PAGE * sizeof (BVT (clib_bihash_kv)),
+                LOAD);
 }
 
 static inline int BV (clib_bihash_search_inline_2_with_hash)
@@ -470,10 +479,17 @@ static inline int BV (clib_bihash_search_inline_2_with_hash)
   BVT (clib_bihash_bucket) * b;
   int i, limit;
 
+/* *INDENT-OFF* */
+  static const BVT (clib_bihash_bucket) mask = {
+    .linear_search = 1,
+    .log2_pages = -1
+  };
+/* *INDENT-ON* */
+
   ASSERT (valuep);
 
 #if BIHASH_LAZY_INSTANTIATE
-  if (PREDICT_FALSE (alloc_arena (h) == 0))
+  if (PREDICT_FALSE (h->instantiated == 0))
     return -1;
 #endif
 
@@ -489,14 +505,18 @@ static inline int BV (clib_bihash_search_inline_2_with_hash)
        CLIB_PAUSE ();
     }
 
-  hash >>= h->log2_nbuckets;
   v = BV (clib_bihash_get_value) (h, b->offset);
 
   /* If the bucket has unresolvable collisions, use linear search */
   limit = BIHASH_KVP_PER_PAGE;
-  v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0;
-  if (PREDICT_FALSE (b->linear_search))
-    limit <<= b->log2_pages;
+
+  if (PREDICT_FALSE (b->as_u64 & mask.as_u64))
+    {
+      if (PREDICT_FALSE (b->linear_search))
+       limit <<= b->log2_pages;
+      else
+       v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
+    }
 
   for (i = 0; i < limit; i++)
     {