[ovs-dev] [PATCH v4 2/7] datapath: Clarify locking.

Pravin Shelar pshelar at nicira.com
Mon Mar 24 20:30:13 UTC 2014


Since you are fixing locking, can you also fix flow-stats access in
ovs_flow_stats_get(). The access is always under ovs-mutex.

On Mon, Mar 24, 2014 at 11:56 AM, Jarno Rajahalme <jrajahalme at nicira.com> wrote:
> Remove unnecessary locking from functions that are always called with
> appropriate locking.
>
> Signed-off-by: Jarno Rajahalme <jrajahalme at nicira.com>
> ---
>  datapath/datapath.c |   13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/datapath/datapath.c b/datapath/datapath.c
> index 918a990..7ce3ea6 100644
> --- a/datapath/datapath.c
> +++ b/datapath/datapath.c
> @@ -175,6 +175,7 @@ static struct hlist_head *vport_hash_bucket(const struct datapath *dp,
>         return &dp->ports[port_no & (DP_VPORT_HASH_BUCKETS - 1)];
>  }
>
> +/* Called with ovs_mutex or RCU read lock. */
>  struct vport *ovs_lookup_vport(const struct datapath *dp, u16 port_no)
>  {
>         struct vport *vport;
> @@ -653,7 +654,7 @@ static size_t ovs_flow_cmd_msg_size(const struct sw_flow_actions *acts)
>                 + nla_total_size(acts->actions_len); /* OVS_FLOW_ATTR_ACTIONS */
>  }
>
> -/* Called with ovs_mutex. */
> +/* Called with ovs_mutex or RCU read lock. */
>  static int ovs_flow_cmd_fill_info(struct sw_flow *flow, struct datapath *dp,
>                                   struct sk_buff *skb, u32 portid,
>                                   u32 seq, u32 flags, u8 cmd)
> @@ -744,6 +745,7 @@ error:
>         return err;
>  }
>
> +/* Must be called with ovs_mutex. */
>  static struct sk_buff *ovs_flow_cmd_alloc_info(struct sw_flow *flow,
>                                                struct genl_info *info)
>  {
> @@ -754,6 +756,7 @@ static struct sk_buff *ovs_flow_cmd_alloc_info(struct sw_flow *flow,
>         return genlmsg_new_unicast(len, info, GFP_KERNEL);
>  }
>
> +/* Must be called with ovs_mutex. */
>  static struct sk_buff *ovs_flow_cmd_build_info(struct sw_flow *flow,
>                                                struct datapath *dp,
>                                                struct genl_info *info,
> @@ -1094,6 +1097,7 @@ static size_t ovs_dp_cmd_msg_size(void)
>         return msgsize;
>  }
>
> +/* Called with ovs_mutex or RCU read lock. */
>  static int ovs_dp_cmd_fill_info(struct datapath *dp, struct sk_buff *skb,
>                                 u32 portid, u32 seq, u32 flags, u8 cmd)
>  {
> @@ -1109,9 +1113,7 @@ static int ovs_dp_cmd_fill_info(struct datapath *dp, struct sk_buff *skb,
>
>         ovs_header->dp_ifindex = get_dpifindex(dp);
>
> -       rcu_read_lock();
>         err = nla_put_string(skb, OVS_DP_ATTR_NAME, ovs_dp_name(dp));
> -       rcu_read_unlock();
>         if (err)
>                 goto nla_put_failure;
>
> @@ -1136,6 +1138,7 @@ error:
>         return -EMSGSIZE;
>  }
>
> +/* Must be called with ovs_mutex. */
>  static struct sk_buff *ovs_dp_cmd_build_info(struct datapath *dp,
>                                              struct genl_info *info, u8 cmd)
>  {
> @@ -1154,7 +1157,7 @@ static struct sk_buff *ovs_dp_cmd_build_info(struct datapath *dp,
>         return skb;
>  }
>
> -/* Called with ovs_mutex. */
> +/* Called with rcu_read_lock or ovs_mutex. */
>  static struct datapath *lookup_datapath(struct net *net,
>                                         struct ovs_header *ovs_header,
>                                         struct nlattr *a[OVS_DP_ATTR_MAX + 1])
> @@ -1166,10 +1169,8 @@ static struct datapath *lookup_datapath(struct net *net,
>         else {
>                 struct vport *vport;
>
> -               rcu_read_lock();
>                 vport = ovs_vport_locate(net, nla_data(a[OVS_DP_ATTR_NAME]));
>                 dp = vport && vport->port_no == OVSP_LOCAL ? vport->dp : NULL;
> -               rcu_read_unlock();
>         }
>         return dp ? dp : ERR_PTR(-ENODEV);
>  }
> --
> 1.7.10.4
>
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