Commit 32359d52 authored by Emilio G. Cota's avatar Emilio G. Cota Committed by Richard Henderson
Browse files

qht: return existing entry when qht_insert fails 



The meaning of "existing" is now changed to "matches in hash and
ht->cmp result". This is saner than just checking the pointer value.

Suggested-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarEmilio G. Cota <cota@braap.org>
Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent 61b8cef1

accel/tcg/translate-all.c

+1 −1
Original line number Diff line number Diff line
@@ -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) {

include/qemu/qht.h

+5 −2
Original line number Diff line number Diff line
@@ -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.

tests/qht-bench.c

+2 −2
Original line number Diff line number Diff line
@@ -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++;

tests/test-qht.c

+7 −1
Original line number Diff line number Diff line
@@ -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]);

    }

}

util/qht.c

+17 −10
Original line number Diff line number Diff line
@@ -511,7 +511,7 @@ 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,

static void *qht_insert__locked(struct qht *ht, struct qht_map *map,

                                struct qht_bucket *head, void *p, uint32_t hash,

                                bool *needs_resize)

{
@@ -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)