1 files changed, 104 insertions, 34 deletions

diff --git a/util/qht.c b/util/qht.c
index 1e3a072e25..aa51be3c52 100644
--- a/util/qht.c
+++ b/util/qht.c
@@ -89,6 +89,19 @@
 #define QHT_BUCKET_ENTRIES 4
 #endif
 
+enum qht_iter_type {
+    QHT_ITER_VOID,    /* do nothing; use retvoid */
+    QHT_ITER_RM,      /* remove element if retbool returns true */
+};
+
+struct qht_iter {
+    union {
+        qht_iter_func_t retvoid;
+        qht_iter_bool_func_t retbool;
+    } f;
+    enum qht_iter_type type;
+};
+
 /*
  * Do _not_ use qemu_mutex_[try]lock directly! Use these macros, otherwise
  * the profiler (QSP) will deadlock.
@@ -223,7 +236,7 @@ static inline void qht_head_init(struct qht_bucket *b)
 }
 
 static inline
-struct qht_bucket *qht_map_to_bucket(struct qht_map *map, uint32_t hash)
+struct qht_bucket *qht_map_to_bucket(const struct qht_map *map, uint32_t hash)
 {
     return &map->buckets[hash & (map->n_buckets - 1)];
 }
@@ -255,7 +268,8 @@ static void qht_map_unlock_buckets(struct qht_map *map)
  * Call with at least a bucket lock held.
  * @map should be the value read before acquiring the lock (or locks).
  */
-static inline bool qht_map_is_stale__locked(struct qht *ht, struct qht_map *map)
+static inline bool qht_map_is_stale__locked(const struct qht *ht,
+                                            const struct qht_map *map)
 {
     return map != ht->map;
 }
@@ -324,12 +338,12 @@ struct qht_bucket *qht_bucket_lock__no_stale(struct qht *ht, uint32_t hash,
     return b;
 }
 
-static inline bool qht_map_needs_resize(struct qht_map *map)
+static inline bool qht_map_needs_resize(const struct qht_map *map)
 {
     return atomic_read(&map->n_added_buckets) > map->n_added_buckets_threshold;
 }
 
-static inline void qht_chain_destroy(struct qht_bucket *head)
+static inline void qht_chain_destroy(const struct qht_bucket *head)
 {
     struct qht_bucket *curr = head->next;
     struct qht_bucket *prev;
@@ -469,10 +483,10 @@ bool qht_reset_size(struct qht *ht, size_t n_elems)
 }
 
 static inline
-void *qht_do_lookup(struct qht_bucket *head, qht_lookup_func_t func,
+void *qht_do_lookup(const struct qht_bucket *head, qht_lookup_func_t func,
                     const void *userp, uint32_t hash)
 {
-    struct qht_bucket *b = head;
+    const struct qht_bucket *b = head;
     int i;
 
     do {
@@ -496,7 +510,7 @@ void *qht_do_lookup(struct qht_bucket *head, qht_lookup_func_t func,
 }
 
 static __attribute__((noinline))
-void *qht_lookup__slowpath(struct qht_bucket *b, qht_lookup_func_t func,
+void *qht_lookup__slowpath(const struct qht_bucket *b, qht_lookup_func_t func,
                            const void *userp, uint32_t hash)
 {
     unsigned int version;
@@ -509,11 +523,11 @@ void *qht_lookup__slowpath(struct qht_bucket *b, qht_lookup_func_t func,
     return ret;
 }
 
-void *qht_lookup_custom(struct qht *ht, const void *userp, uint32_t hash,
+void *qht_lookup_custom(const struct qht *ht, const void *userp, uint32_t hash,
                         qht_lookup_func_t func)
 {
-    struct qht_bucket *b;
-    struct qht_map *map;
+    const struct qht_bucket *b;
+    const struct qht_map *map;
     unsigned int version;
     void *ret;
 
@@ -532,13 +546,16 @@ void *qht_lookup_custom(struct qht *ht, const void *userp, uint32_t hash,
     return qht_lookup__slowpath(b, func, userp, hash);
 }
 
-void *qht_lookup(struct qht *ht, const void *userp, uint32_t hash)
+void *qht_lookup(const struct qht *ht, const void *userp, uint32_t hash)
 {
     return qht_lookup_custom(ht, userp, hash, ht->cmp);
 }
 
-/* call with head->lock held */
-static void *qht_insert__locked(struct qht *ht, struct qht_map *map,
+/*
+ * call with head->lock held
+ * @ht is const since it is only used for ht->cmp()
+ */
+static void *qht_insert__locked(const struct qht *ht, struct qht_map *map,
                                 struct qht_bucket *head, void *p, uint32_t hash,
                                 bool *needs_resize)
 {
@@ -632,7 +649,7 @@ bool qht_insert(struct qht *ht, void *p, uint32_t hash, void **existing)
     return false;
 }
 
-static inline bool qht_entry_is_last(struct qht_bucket *b, int pos)
+static inline bool qht_entry_is_last(const struct qht_bucket *b, int pos)
 {
     if (pos == QHT_BUCKET_ENTRIES - 1) {
         if (b->next == NULL) {
@@ -658,7 +675,7 @@ qht_entry_move(struct qht_bucket *to, int i, struct qht_bucket *from, int j)
 }
 
 /*
- * Find the last valid entry in @head, and swap it with @orig[pos], which has
+ * Find the last valid entry in @orig, and swap it with @orig[pos], which has
  * just been invalidated.
  */
 static inline void qht_bucket_remove_entry(struct qht_bucket *orig, int pos)
@@ -692,8 +709,7 @@ static inline void qht_bucket_remove_entry(struct qht_bucket *orig, int pos)
 
 /* call with b->lock held */
 static inline
-bool qht_remove__locked(struct qht_map *map, struct qht_bucket *head,
-                        const void *p, uint32_t hash)
+bool qht_remove__locked(struct qht_bucket *head, const void *p, uint32_t hash)
 {
     struct qht_bucket *b = head;
     int i;
@@ -728,15 +744,16 @@ bool qht_remove(struct qht *ht, const void *p, uint32_t hash)
     qht_debug_assert(p);
 
     b = qht_bucket_lock__no_stale(ht, hash, &map);
-    ret = qht_remove__locked(map, b, p, hash);
+    ret = qht_remove__locked(b, p, hash);
     qht_bucket_debug__locked(b);
     qemu_spin_unlock(&b->lock);
     return ret;
 }
 
-static inline void qht_bucket_iter(struct qht *ht, struct qht_bucket *b,
-                                   qht_iter_func_t func, void *userp)
+static inline void qht_bucket_iter(struct qht_bucket *head,
+                                   const struct qht_iter *iter, void *userp)
 {
+    struct qht_bucket *b = head;
     int i;
 
     do {
@@ -744,37 +761,83 @@ static inline void qht_bucket_iter(struct qht *ht, struct qht_bucket *b,
             if (b->pointers[i] == NULL) {
                 return;
             }
-            func(ht, b->pointers[i], b->hashes[i], userp);
+            switch (iter->type) {
+            case QHT_ITER_VOID:
+                iter->f.retvoid(b->pointers[i], b->hashes[i], userp);
+                break;
+            case QHT_ITER_RM:
+                if (iter->f.retbool(b->pointers[i], b->hashes[i], userp)) {
+                    /* replace i with the last valid element in the bucket */
+                    seqlock_write_begin(&head->sequence);
+                    qht_bucket_remove_entry(b, i);
+                    seqlock_write_end(&head->sequence);
+                    qht_bucket_debug__locked(b);
+                    /* reevaluate i, since it just got replaced */
+                    i--;
+                    continue;
+                }
+                break;
+            default:
+                g_assert_not_reached();
+            }
         }
         b = b->next;
     } while (b);
 }
 
 /* call with all of the map's locks held */
-static inline void qht_map_iter__all_locked(struct qht *ht, struct qht_map *map,
-                                            qht_iter_func_t func, void *userp)
+static inline void qht_map_iter__all_locked(struct qht_map *map,
+                                            const struct qht_iter *iter,
+                                            void *userp)
 {
     size_t i;
 
     for (i = 0; i < map->n_buckets; i++) {
-        qht_bucket_iter(ht, &map->buckets[i], func, userp);
+        qht_bucket_iter(&map->buckets[i], iter, userp);
     }
 }
 
-void qht_iter(struct qht *ht, qht_iter_func_t func, void *userp)
+static inline void
+do_qht_iter(struct qht *ht, const struct qht_iter *iter, void *userp)
 {
     struct qht_map *map;
 
     map = atomic_rcu_read(&ht->map);
     qht_map_lock_buckets(map);
-    /* Note: ht here is merely for carrying ht->mode; ht->map won't be read */
-    qht_map_iter__all_locked(ht, map, func, userp);
+    qht_map_iter__all_locked(map, iter, userp);
     qht_map_unlock_buckets(map);
 }
 
-static void qht_map_copy(struct qht *ht, void *p, uint32_t hash, void *userp)
+void qht_iter(struct qht *ht, qht_iter_func_t func, void *userp)
+{
+    const struct qht_iter iter = {
+        .f.retvoid = func,
+        .type = QHT_ITER_VOID,
+    };
+
+    do_qht_iter(ht, &iter, userp);
+}
+
+void qht_iter_remove(struct qht *ht, qht_iter_bool_func_t func, void *userp)
+{
+    const struct qht_iter iter = {
+        .f.retbool = func,
+        .type = QHT_ITER_RM,
+    };
+
+    do_qht_iter(ht, &iter, userp);
+}
+
+struct qht_map_copy_data {
+    struct qht *ht;
+    struct qht_map *new;
+};
+
+static void qht_map_copy(void *p, uint32_t hash, void *userp)
 {
-    struct qht_map *new = userp;
+    struct qht_map_copy_data *data = userp;
+    struct qht *ht = data->ht;
+    struct qht_map *new = data->new;
     struct qht_bucket *b = qht_map_to_bucket(new, hash);
 
     /* no need to acquire b->lock because no thread has seen this map yet */
@@ -788,6 +851,11 @@ static void qht_map_copy(struct qht *ht, void *p, uint32_t hash, void *userp)
 static void qht_do_resize_reset(struct qht *ht, struct qht_map *new, bool reset)
 {
     struct qht_map *old;
+    const struct qht_iter iter = {
+        .f.retvoid = qht_map_copy,
+        .type = QHT_ITER_VOID,
+    };
+    struct qht_map_copy_data data;
 
     old = ht->map;
     qht_map_lock_buckets(old);
@@ -802,7 +870,9 @@ static void qht_do_resize_reset(struct qht *ht, struct qht_map *new, bool reset)
     }
 
     g_assert(new->n_buckets != old->n_buckets);
-    qht_map_iter__all_locked(ht, old, qht_map_copy, new);
+    data.ht = ht;
+    data.new = new;
+    qht_map_iter__all_locked(old, &iter, &data);
     qht_map_debug__all_locked(new);
 
     atomic_rcu_set(&ht->map, new);
@@ -829,9 +899,9 @@ bool qht_resize(struct qht *ht, size_t n_elems)
 }
 
 /* pass @stats to qht_statistics_destroy() when done */
-void qht_statistics_init(struct qht *ht, struct qht_stats *stats)
+void qht_statistics_init(const struct qht *ht, struct qht_stats *stats)
 {
-    struct qht_map *map;
+    const struct qht_map *map;
     int i;
 
     map = atomic_rcu_read(&ht->map);
@@ -848,8 +918,8 @@ void qht_statistics_init(struct qht *ht, struct qht_stats *stats)
     stats->head_buckets = map->n_buckets;
 
     for (i = 0; i < map->n_buckets; i++) {
-        struct qht_bucket *head = &map->buckets[i];
-        struct qht_bucket *b;
+        const struct qht_bucket *head = &map->buckets[i];
+        const struct qht_bucket *b;
         unsigned int version;
         size_t buckets;
         size_t entries;