[dpdk-dev] [PATCH v2 3/4] hash: keep the list locked at creation
De Lara Guarch, Pablo
pablo.de.lara.guarch at intel.com
Tue Apr 5 13:05:46 CEST 2016
> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Olivier Matz
> Sent: Tuesday, April 05, 2016 8:36 AM
> To: dev at dpdk.org
> Cc: Richardson, Bruce
> Subject: [dpdk-dev] [PATCH v2 3/4] hash: keep the list locked at creation
>
> To avoid a race condition while creating a new hash object, the
> list has to be locked before the lookup, and released only once the
> new object is added in the list.
>
> As the lock is held by the rte_ring_create(), move its creation at the
> beginning of the function and only take the lock after the ring is
> created to avoid a deadlock.
>
> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
> ---
> lib/librte_hash/rte_cuckoo_hash.c | 68 ++++++++++++++++++++++-------------
> ----
> 1 file changed, 38 insertions(+), 30 deletions(-)
>
> diff --git a/lib/librte_hash/rte_cuckoo_hash.c
> b/lib/librte_hash/rte_cuckoo_hash.c
> index ccec2db..63a74fd 100644
> --- a/lib/librte_hash/rte_cuckoo_hash.c
> +++ b/lib/librte_hash/rte_cuckoo_hash.c
> @@ -226,19 +226,46 @@ rte_hash_create(const struct rte_hash_parameters
> *params)
> if (params->extra_flag &
> RTE_HASH_EXTRA_FLAGS_TRANS_MEM_SUPPORT)
> hw_trans_mem_support = 1;
>
> + /* Store all keys and leave the first entry as a dummy entry for
> lookup_bulk */
> + if (hw_trans_mem_support)
> + /*
> + * Increase number of slots by total number of indices
> + * that can be stored in the lcore caches
> + * except for the first cache
> + */
> + num_key_slots = params->entries + (RTE_MAX_LCORE - 1) *
> + LCORE_CACHE_SIZE + 1;
> + else
> + num_key_slots = params->entries + 1;
> +
> + snprintf(ring_name, sizeof(ring_name), "HT_%s", params->name);
> + r = rte_ring_create(ring_name, rte_align32pow2(num_key_slots),
> + params->socket_id, 0);
> + if (r == NULL) {
> + RTE_LOG(ERR, HASH, "memory allocation failed\n");
> + goto err;
> + }
> +
> snprintf(hash_name, sizeof(hash_name), "HT_%s", params->name);
>
> - /* Guarantee there's no existing */
> - h = rte_hash_find_existing(params->name);
> - if (h != NULL) {
> + rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);
> +
> + /* guarantee there's no existing: this is normally already checked
> + * by ring creation above */
> + TAILQ_FOREACH(te, hash_list, next) {
> + h = (struct rte_hash *) te->data;
> + if (strncmp(params->name, h->name, RTE_HASH_NAMESIZE)
> == 0)
> + break;
> + }
> + if (te != NULL) {
> rte_errno = EEXIST;
> - return NULL;
> + goto err_unlock;
> }
>
> te = rte_zmalloc("HASH_TAILQ_ENTRY", sizeof(*te), 0);
> if (te == NULL) {
> RTE_LOG(ERR, HASH, "tailq entry allocation failed\n");
> - goto err;
> + goto err_unlock;
> }
>
> h = (struct rte_hash *)rte_zmalloc_socket(hash_name, sizeof(struct
> rte_hash),
> @@ -246,7 +273,7 @@ rte_hash_create(const struct rte_hash_parameters
> *params)
>
> if (h == NULL) {
> RTE_LOG(ERR, HASH, "memory allocation failed\n");
> - goto err;
> + goto err_unlock;
> }
>
> const uint32_t num_buckets = rte_align32pow2(params->entries)
> @@ -258,23 +285,10 @@ rte_hash_create(const struct rte_hash_parameters
> *params)
>
> if (buckets == NULL) {
> RTE_LOG(ERR, HASH, "memory allocation failed\n");
> - goto err;
> + goto err_unlock;
> }
>
> const uint32_t key_entry_size = sizeof(struct rte_hash_key) +
> params->key_len;
> -
> - /* Store all keys and leave the first entry as a dummy entry for
> lookup_bulk */
> - if (hw_trans_mem_support)
> - /*
> - * Increase number of slots by total number of indices
> - * that can be stored in the lcore caches
> - * except for the first cache
> - */
> - num_key_slots = params->entries + (RTE_MAX_LCORE - 1) *
> - LCORE_CACHE_SIZE + 1;
> - else
> - num_key_slots = params->entries + 1;
> -
> const uint64_t key_tbl_size = (uint64_t) key_entry_size *
> num_key_slots;
>
> k = rte_zmalloc_socket(NULL, key_tbl_size,
> @@ -282,7 +296,7 @@ rte_hash_create(const struct rte_hash_parameters
> *params)
>
> if (k == NULL) {
> RTE_LOG(ERR, HASH, "memory allocation failed\n");
> - goto err;
> + goto err_unlock;
> }
>
> /*
> @@ -325,14 +339,6 @@ rte_hash_create(const struct rte_hash_parameters
> *params)
> h->rte_hash_cmp_eq = memcmp;
> #endif
>
> - snprintf(ring_name, sizeof(ring_name), "HT_%s", params->name);
> - r = rte_ring_create(ring_name, rte_align32pow2(num_key_slots),
> - params->socket_id, 0);
> - if (r == NULL) {
> - RTE_LOG(ERR, HASH, "memory allocation failed\n");
> - goto err;
> - }
> -
> if (hw_trans_mem_support) {
> h->local_free_slots = rte_zmalloc_socket(NULL,
> sizeof(struct lcore_cache) * RTE_MAX_LCORE,
> @@ -359,13 +365,15 @@ rte_hash_create(const struct rte_hash_parameters
> *params)
> for (i = 1; i < params->entries + 1; i++)
> rte_ring_sp_enqueue(r, (void *)((uintptr_t) i));
>
> - rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);
> te->data = (void *) h;
> TAILQ_INSERT_TAIL(hash_list, te, next);
> rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
>
> return h;
> +err_unlock:
> + rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
> err:
> + rte_ring_free(r);
This patch does not apply cleanly, since another patch for this file last week was applied
(http://dpdk.org/dev/patchwork/patch/11896/).
Could you rebase this patchset against mainline?
Thanks,
Pablo
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