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array: More locking fixes #400

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merged 2 commits into from
Jun 8, 2020
Merged

array: More locking fixes #400

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b22ca95
array: More locking fixes
chrissie-c Jun 5, 2020
6ae509b
We also need to protect a->max_elements
chrissie-c Jun 8, 2020
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30 changes: 24 additions & 6 deletions lib/array.c
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Original file line number Diff line number Diff line change
Expand Up @@ -122,14 +122,19 @@ qb_array_index(struct qb_array * a, int32_t idx, void **element_out)
if (idx < 0) {
return -ERANGE;
}
(void)qb_thread_lock(a->grow_lock);
if ((uint32_t) idx >= a->max_elements) {
if (a->autogrow_elements == 0) {
(void)qb_thread_unlock(a->grow_lock);
return -ERANGE;
} else {
/* qb_array_grow gets the lock */
(void)qb_thread_unlock(a->grow_lock);
rc = qb_array_grow(a, idx + 1);
if (rc != 0) {
return rc;
}
(void)qb_thread_lock(a->grow_lock);
}
}
b = BIN_NUM_GET((uint32_t) idx);
Expand All @@ -138,8 +143,6 @@ qb_array_index(struct qb_array * a, int32_t idx, void **element_out)
if (b >= a->num_bins || a->bin[b] == NULL) {
int32_t bin_alloced = QB_FALSE;

(void)qb_thread_lock(a->grow_lock);

if (b >= a->num_bins) {
rc = _grow_bin_array(a, b + 1);
if (rc < 0) {
Expand All @@ -154,11 +157,13 @@ qb_array_index(struct qb_array * a, int32_t idx, void **element_out)
}
bin_alloced = QB_TRUE;
}

/* new_bin_cb() needs to be called unlocked so can't extend the lock after the if block */
(void)qb_thread_unlock(a->grow_lock);
if (bin_alloced && a->new_bin_cb) {
a->new_bin_cb(a, b);
}
} else {
(void)qb_thread_unlock(a->grow_lock);
}

elem = ELEM_NUM_GET(idx);
Expand Down Expand Up @@ -188,10 +193,15 @@ qb_array_new_bin_cb_set(struct qb_array * a, qb_array_new_bin_cb_fn fn)
size_t
qb_array_num_bins_get(struct qb_array * a)
{
size_t bins;

if (a == NULL) {
return -EINVAL;
}
return a->num_bins;
(void)qb_thread_lock(a->grow_lock);
bins = a->num_bins;
(void)qb_thread_unlock(a->grow_lock);
return bins;
}

size_t
Expand All @@ -212,25 +222,33 @@ qb_array_grow(struct qb_array * a, size_t max_elements)
if (a == NULL || max_elements > QB_ARRAY_MAX_ELEMENTS) {
return -EINVAL;
}

(void)qb_thread_lock(a->grow_lock);
if (max_elements <= a->max_elements) {
(void)qb_thread_unlock(a->grow_lock);
return 0;
}
a->max_elements = max_elements;
b = QB_MIN((max_elements / MAX_ELEMENTS_PER_BIN) + 1, MAX_BINS);
if (b > a->num_bins) {
(void)qb_thread_lock(a->grow_lock);
if (b >= a->num_bins) {
rc = _grow_bin_array(a, b + 1);
}
(void)qb_thread_unlock(a->grow_lock);
}
(void)qb_thread_unlock(a->grow_lock);
return rc;
}

void
qb_array_free(struct qb_array *a)
{
size_t i;

/* In theory we should lock before accessing a->num_bins
* but as we're freeing the whole array here it seems
* a bit pointless as any other threads would segv when we
* unlock anyway
*/
for (i = 0; i < a->num_bins; i++) {
free(a->bin[i]);
}
Expand Down