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-rw-r--r--accel/tcg/translate-all.c2
-rw-r--r--include/qemu/qht.h7
-rw-r--r--tests/qht-bench.c4
-rw-r--r--tests/test-qht.c8
-rw-r--r--util/qht.c27
5 files changed, 32 insertions, 16 deletions
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index f39123b..1695f8c 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1242,7 +1242,7 @@ static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc,
/* add in the hash table */
h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK,
tb->trace_vcpu_dstate);
- qht_insert(&tb_ctx.htable, tb, h);
+ qht_insert(&tb_ctx.htable, tb, h, NULL);
#ifdef CONFIG_USER_ONLY
if (DEBUG_TB_CHECK_GATE) {
diff --git a/include/qemu/qht.h b/include/qemu/qht.h
index 5f03a0f..1fb9116 100644
--- a/include/qemu/qht.h
+++ b/include/qemu/qht.h
@@ -70,6 +70,7 @@ void qht_destroy(struct qht *ht);
* @ht: QHT to insert to
* @p: pointer to be inserted
* @hash: hash corresponding to @p
+ * @existing: address where the pointer to an existing entry can be copied to
*
* Attempting to insert a NULL @p is a bug.
* Inserting the same pointer @p with different @hash values is a bug.
@@ -78,9 +79,11 @@ void qht_destroy(struct qht *ht);
* inserted into the hash table.
*
* Returns true on success.
- * Returns false if the @p-@hash pair already exists in the hash table.
+ * Returns false if there is an existing entry in the table that is equivalent
+ * (i.e. ht->cmp matches and the hash is the same) to @p-@h. If @existing
+ * is !NULL, a pointer to this existing entry is copied to it.
*/
-bool qht_insert(struct qht *ht, void *p, uint32_t hash);
+bool qht_insert(struct qht *ht, void *p, uint32_t hash, void **existing);
/**
* qht_lookup_custom - Look up a pointer using a custom comparison function.
diff --git a/tests/qht-bench.c b/tests/qht-bench.c
index c94ac25..f492b3a 100644
--- a/tests/qht-bench.c
+++ b/tests/qht-bench.c
@@ -163,7 +163,7 @@ static void do_rw(struct thread_info *info)
bool written = false;
if (qht_lookup(&ht, p, hash) == NULL) {
- written = qht_insert(&ht, p, hash);
+ written = qht_insert(&ht, p, hash, NULL);
}
if (written) {
stats->in++;
@@ -322,7 +322,7 @@ static void htable_init(void)
r = xorshift64star(r);
p = &keys[r & (init_range - 1)];
hash = h(*p);
- if (qht_insert(&ht, p, hash)) {
+ if (qht_insert(&ht, p, hash, NULL)) {
break;
}
retries++;
diff --git a/tests/test-qht.c b/tests/test-qht.c
index b069881..dda6a06 100644
--- a/tests/test-qht.c
+++ b/tests/test-qht.c
@@ -27,11 +27,17 @@ static void insert(int a, int b)
for (i = a; i < b; i++) {
uint32_t hash;
+ void *existing;
+ bool inserted;
arr[i] = i;
hash = i;
- qht_insert(&ht, &arr[i], hash);
+ inserted = qht_insert(&ht, &arr[i], hash, NULL);
+ g_assert_true(inserted);
+ inserted = qht_insert(&ht, &arr[i], hash, &existing);
+ g_assert_false(inserted);
+ g_assert_true(existing == &arr[i]);
}
}
diff --git a/util/qht.c b/util/qht.c
index 487e923..c138777 100644
--- a/util/qht.c
+++ b/util/qht.c
@@ -511,9 +511,9 @@ void *qht_lookup(struct qht *ht, const void *userp, uint32_t hash)
}
/* call with head->lock held */
-static bool qht_insert__locked(struct qht *ht, struct qht_map *map,
- struct qht_bucket *head, void *p, uint32_t hash,
- bool *needs_resize)
+static void *qht_insert__locked(struct qht *ht, struct qht_map *map,
+ struct qht_bucket *head, void *p, uint32_t hash,
+ bool *needs_resize)
{
struct qht_bucket *b = head;
struct qht_bucket *prev = NULL;
@@ -523,8 +523,9 @@ static bool qht_insert__locked(struct qht *ht, struct qht_map *map,
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->pointers[i]) {
- if (unlikely(b->pointers[i] == p)) {
- return false;
+ if (unlikely(b->hashes[i] == hash &&
+ ht->cmp(b->pointers[i], p))) {
+ return b->pointers[i];
}
} else {
goto found;
@@ -553,7 +554,7 @@ static bool qht_insert__locked(struct qht *ht, struct qht_map *map,
atomic_set(&b->hashes[i], hash);
atomic_set(&b->pointers[i], p);
seqlock_write_end(&head->sequence);
- return true;
+ return NULL;
}
static __attribute__((noinline)) void qht_grow_maybe(struct qht *ht)
@@ -577,25 +578,31 @@ static __attribute__((noinline)) void qht_grow_maybe(struct qht *ht)
qemu_mutex_unlock(&ht->lock);
}
-bool qht_insert(struct qht *ht, void *p, uint32_t hash)
+bool qht_insert(struct qht *ht, void *p, uint32_t hash, void **existing)
{
struct qht_bucket *b;
struct qht_map *map;
bool needs_resize = false;
- bool ret;
+ void *prev;
/* NULL pointers are not supported */
qht_debug_assert(p);
b = qht_bucket_lock__no_stale(ht, hash, &map);
- ret = qht_insert__locked(ht, map, b, p, hash, &needs_resize);
+ prev = qht_insert__locked(ht, map, b, p, hash, &needs_resize);
qht_bucket_debug__locked(b);
qemu_spin_unlock(&b->lock);
if (unlikely(needs_resize) && ht->mode & QHT_MODE_AUTO_RESIZE) {
qht_grow_maybe(ht);
}
- return ret;
+ if (likely(prev == NULL)) {
+ return true;
+ }
+ if (existing) {
+ *existing = prev;
+ }
+ return false;
}
static inline bool qht_entry_is_last(struct qht_bucket *b, int pos)