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Merge branch 'jk/index-pack-threading-races' into maint
When receiving an invalid pack stream that records the same object twice, multiple threads got confused due to a race. * jk/index-pack-threading-races: index-pack: fix race condition with duplicate bases
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commit
46092ebf22
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@ -112,6 +112,10 @@ static pthread_mutex_t deepest_delta_mutex;
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#define deepest_delta_lock() lock_mutex(&deepest_delta_mutex)
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#define deepest_delta_unlock() unlock_mutex(&deepest_delta_mutex)
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static pthread_mutex_t type_cas_mutex;
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#define type_cas_lock() lock_mutex(&type_cas_mutex)
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#define type_cas_unlock() unlock_mutex(&type_cas_mutex)
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static pthread_key_t key;
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static inline void lock_mutex(pthread_mutex_t *mutex)
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@ -135,6 +139,7 @@ static void init_thread(void)
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init_recursive_mutex(&read_mutex);
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pthread_mutex_init(&counter_mutex, NULL);
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pthread_mutex_init(&work_mutex, NULL);
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pthread_mutex_init(&type_cas_mutex, NULL);
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if (show_stat)
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pthread_mutex_init(&deepest_delta_mutex, NULL);
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pthread_key_create(&key, NULL);
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@ -157,6 +162,7 @@ static void cleanup_thread(void)
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pthread_mutex_destroy(&read_mutex);
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pthread_mutex_destroy(&counter_mutex);
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pthread_mutex_destroy(&work_mutex);
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pthread_mutex_destroy(&type_cas_mutex);
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if (show_stat)
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pthread_mutex_destroy(&deepest_delta_mutex);
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for (i = 0; i < nr_threads; i++)
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@ -862,7 +868,6 @@ static void resolve_delta(struct object_entry *delta_obj,
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{
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void *base_data, *delta_data;
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delta_obj->real_type = base->obj->real_type;
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if (show_stat) {
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delta_obj->delta_depth = base->obj->delta_depth + 1;
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deepest_delta_lock();
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@ -888,6 +893,26 @@ static void resolve_delta(struct object_entry *delta_obj,
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counter_unlock();
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}
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/*
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* Standard boolean compare-and-swap: atomically check whether "*type" is
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* "want"; if so, swap in "set" and return true. Otherwise, leave it untouched
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* and return false.
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*/
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static int compare_and_swap_type(enum object_type *type,
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enum object_type want,
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enum object_type set)
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{
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enum object_type old;
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type_cas_lock();
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old = *type;
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if (old == want)
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*type = set;
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type_cas_unlock();
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return old == want;
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}
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static struct base_data *find_unresolved_deltas_1(struct base_data *base,
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struct base_data *prev_base)
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{
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@ -915,7 +940,10 @@ static struct base_data *find_unresolved_deltas_1(struct base_data *base,
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struct object_entry *child = objects + deltas[base->ref_first].obj_no;
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struct base_data *result = alloc_base_data();
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assert(child->real_type == OBJ_REF_DELTA);
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if (!compare_and_swap_type(&child->real_type, OBJ_REF_DELTA,
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base->obj->real_type))
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die("BUG: child->real_type != OBJ_REF_DELTA");
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resolve_delta(child, base, result);
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if (base->ref_first == base->ref_last && base->ofs_last == -1)
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free_base_data(base);
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@ -929,6 +957,7 @@ static struct base_data *find_unresolved_deltas_1(struct base_data *base,
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struct base_data *result = alloc_base_data();
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assert(child->real_type == OBJ_OFS_DELTA);
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child->real_type = base->obj->real_type;
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resolve_delta(child, base, result);
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if (base->ofs_first == base->ofs_last)
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free_base_data(base);
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