[ovs-dev] [PATCH v2 1/4] ofproto: Update access rules for 'flow_cookie'.

Jarno Rajahalme jarno at ovn.org
Wed Dec 21 18:40:23 UTC 2016


Acked-by: Jarno Rajahalme <jarno at ovn.org>

> On Dec 20, 2016, at 11:03 PM, Ben Pfaff <blp at ovn.org> wrote:
> 
> The 'flow_cookie' member of struct rule is read during flow translation
> without holding a mutex, breaking the documented OVS_GUARDED access rule.
> However, the flow_cookie member is actually never modified after a rule is
> initialized, so this commit changes the access rules to reflect that.
> 
> Signed-off-by: Ben Pfaff <blp at ovn.org>
> ---
> ofproto/ofproto-provider.h | 4 ++--
> ofproto/ofproto.c          | 5 +++--
> 2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/ofproto/ofproto-provider.h b/ofproto/ofproto-provider.h
> index c515779..3739ebc 100644
> --- a/ofproto/ofproto-provider.h
> +++ b/ofproto/ofproto-provider.h
> @@ -365,8 +365,8 @@ struct rule {
>     struct ovs_refcount ref_count;
> 
>     /* A "flow cookie" is the OpenFlow name for a 64-bit value associated with
> -     * a flow.. */
> -    ovs_be64 flow_cookie OVS_GUARDED;
> +     * a flow. */
> +    const ovs_be64 flow_cookie; /* Immutable once rule is constructed. */
>     struct hindex_node cookie_node OVS_GUARDED_BY(ofproto_mutex);
> 
>     enum ofputil_flow_mod_flags flags OVS_GUARDED;
> diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
> index 4f43c45..58295a1 100644
> --- a/ofproto/ofproto.c
> +++ b/ofproto/ofproto.c
> @@ -4859,7 +4859,7 @@ ofproto_rule_create(struct ofproto *ofproto, struct cls_rule *cr,
> 
>     ovs_mutex_init(&rule->mutex);
>     ovs_mutex_lock(&rule->mutex);
> -    rule->flow_cookie = new_cookie;
> +    *CONST_CAST(ovs_be64 *, &rule->flow_cookie) = new_cookie;
>     rule->created = rule->modified = time_msec();
>     rule->idle_timeout = idle_timeout;
>     rule->hard_timeout = hard_timeout;
> @@ -5098,7 +5098,8 @@ replace_rule_start(struct ofproto *ofproto, struct ofproto_flow_mod *ofm,
>                 new_rule->created = old_rule->created;
>             }
>             if (!change_cookie) {
> -                new_rule->flow_cookie = old_rule->flow_cookie;
> +                *CONST_CAST(ovs_be64 *, &new_rule->flow_cookie)
> +                    = old_rule->flow_cookie;
>             }
>             ovs_mutex_unlock(&old_rule->mutex);
>             ovs_mutex_unlock(&new_rule->mutex);
> -- 
> 2.10.2
> 
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