[ovs-dev] [dpif-netdev 11/15] dpif-netdev: Take advantage of ovs_refcount for dp_netdev.

[Pravin Shelar]

On Fri, Dec 27, 2013 at 8:03 PM, Ben Pfaff <blp at nicira.com> wrote:
> By making "destroyed" own a reference, we can treat dp_netdev's ref_cnt
> like any other in Open vSwitch.
>
> Signed-off-by: Ben Pfaff <blp at nicira.com>

Looks good to me.
> ---
>  lib/dpif-netdev.c |   23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index b890e4f..62837b0 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -91,8 +91,8 @@ struct dp_netdev_queue {
>  struct dp_netdev {
>      const struct dpif_class *class;
>      char *name;
> -    int open_cnt;
> -    bool destroyed;
> +    struct ovs_refcount ref_cnt;
> +    atomic_flag destroyed;
>
>      struct dp_netdev_queue queues[N_QUEUES];
>      struct classifier cls;      /* Classifier. */
> @@ -224,7 +224,7 @@ create_dpif_netdev(struct dp_netdev *dp)
>      uint16_t netflow_id = hash_string(dp->name, 0);
>      struct dpif_netdev *dpif;
>
> -    dp->open_cnt++;
> +    ovs_refcount_ref(&dp->ref_cnt);
>
>      dpif = xmalloc(sizeof *dpif);
>      dpif_init(&dpif->dpif, dp->class, dp->name, netflow_id >> 8, netflow_id);
> @@ -286,7 +286,8 @@ create_dp_netdev(const char *name, const struct dpif_class *class,
>      dp = xzalloc(sizeof *dp);
>      dp->class = class;
>      dp->name = xstrdup(name);
> -    dp->open_cnt = 0;
> +    ovs_refcount_init(&dp->ref_cnt);
> +    atomic_flag_init(&dp->destroyed);
>      for (i = 0; i < N_QUEUES; i++) {
>          dp->queues[i].head = dp->queues[i].tail = 0;
>      }
> @@ -371,6 +372,8 @@ dp_netdev_free(struct dp_netdev *dp)
>      hmap_destroy(&dp->flow_table);
>      seq_destroy(dp->port_seq);
>      hmap_destroy(&dp->ports);
> +    atomic_flag_destroy(&dp->destroyed);
> +    ovs_refcount_destroy(&dp->ref_cnt);
>      free(dp->name);
>      free(dp);
>  }
> @@ -382,8 +385,7 @@ dpif_netdev_close(struct dpif *dpif)
>
>      ovs_mutex_lock(&dp_netdev_mutex);
>
> -    ovs_assert(dp->open_cnt > 0);
> -    if (--dp->open_cnt == 0 && dp->destroyed) {
> +    if (ovs_refcount_unref(&dp->ref_cnt) == 1) {
>          shash_find_and_delete(&dp_netdevs, dp->name);
>          dp_netdev_free(dp);
>      }
> @@ -397,9 +399,12 @@ dpif_netdev_destroy(struct dpif *dpif)
>  {
>      struct dp_netdev *dp = get_dp_netdev(dpif);
>
> -    ovs_mutex_lock(&dp_netdev_mutex);
> -    dp->destroyed = true;
> -    ovs_mutex_unlock(&dp_netdev_mutex);
> +    if (!atomic_flag_test_and_set(&dp->destroyed)) {
> +        if (ovs_refcount_unref(&dp->ref_cnt) == 1) {
> +            /* Can't happen: 'dpif' still owns a reference to 'dp'. */
> +            OVS_NOT_REACHED();
> +        }
> +    }
>
>      return 0;
>  }
> --
> 1.7.10.4
>
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