A datapath pointer is available only when holding a lock. Change
ovs_flow_cmd_fill_info() and ovs_flow_cmd_build_info() to take a
dp_ifindex directly, rather than a datapath pointer that is then
(only) used to get the dp_ifindex. This is useful, since the
dp_ifindex is available even when the datapath pointer is not, both
before and after taking a lock, which makes further critical section
reduction possible.
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
v5: Split to a separate patch, relaxed locking requirements.
datapath/datapath.c | 58 ++++++++++++++++++++++++++++++++-------------------
datapath/flow.c | 6 ++++--
datapath/flow.h | 2 +-
3 files changed, 41 insertions(+), 25 deletions(-)
diff --git a/datapath/datapath.c b/datapath/datapath.c
index d1b0155..01913f6 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -663,8 +663,17 @@ 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 or RCU read lock. */
-static int ovs_flow_cmd_fill_info(struct sw_flow *flow, struct datapath *dp,
+/* Allow a flow to be accessed if:
+ * - RCU read lock is held, or
+ * - OVS mutex is held, or
+ * - the flow has already been removed from the flow table. */
+#define ovsl_dereference_flow_acts(flow) \
+ rcu_dereference_check(flow->sf_acts, (lockdep_ovsl_is_held() \
+ || ovs_flow_removed(flow)))
+
+/* Must be called with rcu_read_lock or ovs_mutex if 'flow' is in the flow
+ * table. */
+static int ovs_flow_cmd_fill_info(const struct sw_flow *flow, int dp_ifindex,
struct sk_buff *skb, u32 portid,
u32 seq, u32 flags, u8 cmd)
{
@@ -681,7 +690,7 @@ static int ovs_flow_cmd_fill_info(struct sw_flow *flow,
struct datapath *dp,
if (!ovs_header)
return -EMSGSIZE;
- ovs_header->dp_ifindex = get_dpifindex(dp);
+ ovs_header->dp_ifindex = dp_ifindex;
/* Fill flow key. */
nla = nla_nest_start(skb, OVS_FLOW_ATTR_KEY);
@@ -730,8 +739,7 @@ static int ovs_flow_cmd_fill_info(struct sw_flow *flow,
struct datapath *dp,
if (start) {
const struct sw_flow_actions *sf_acts;
- sf_acts = rcu_dereference_ovsl(flow->sf_acts);
-
+ sf_acts = ovsl_dereference_flow_acts(flow);
err = ovs_nla_put_actions(sf_acts->actions,
sf_acts->actions_len, skb);
if (!err)
@@ -754,8 +762,9 @@ error:
return err;
}
-/* Must be called with ovs_mutex. */
-static struct sk_buff *ovs_flow_cmd_alloc_info(struct sw_flow *flow,
+/* Must be called with rcu_read_lock or ovs_mutex if 'flow' is in the flow
+ * table. */
+static struct sk_buff *ovs_flow_cmd_alloc_info(const struct sw_flow *flow,
struct genl_info *info,
bool always)
{
@@ -765,7 +774,7 @@ static struct sk_buff *ovs_flow_cmd_alloc_info(struct
sw_flow *flow,
if (!always && !ovs_must_notify(info, &ovs_dp_flow_multicast_group))
return NULL;
- len = ovs_flow_cmd_msg_size(ovsl_dereference(flow->sf_acts));
+ len = ovs_flow_cmd_msg_size(ovsl_dereference_flow_acts(flow));
skb = genlmsg_new_unicast(len, info, GFP_KERNEL);
@@ -775,11 +784,12 @@ static struct sk_buff *ovs_flow_cmd_alloc_info(struct
sw_flow *flow,
return skb;
}
-/* 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,
- u8 cmd, bool always)
+/* Must be called with rcu_read_lock or ovs_mutex if 'flow' is in the flow
+ * table. */
+static struct sk_buff *ovs_flow_cmd_build_info(const struct sw_flow *flow,
+ int dp_ifindex,
+ struct genl_info *info, u8 cmd,
+ bool always)
{
struct sk_buff *skb;
int retval;
@@ -788,8 +798,9 @@ static struct sk_buff *ovs_flow_cmd_build_info(struct
sw_flow *flow,
if (!skb || IS_ERR(skb))
return skb;
- retval = ovs_flow_cmd_fill_info(flow, dp, skb, info->snd_portid,
- info->snd_seq, 0, cmd);
+ retval = ovs_flow_cmd_fill_info(flow, dp_ifindex, skb,
+ info->snd_portid, info->snd_seq, 0,
+ cmd);
BUG_ON(retval < 0);
return skb;
}
@@ -870,8 +881,8 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb,
struct genl_info *info)
goto err_flow_free;
}
- reply = ovs_flow_cmd_build_info(flow, dp, info,
- OVS_FLOW_CMD_NEW, false);
+ reply = ovs_flow_cmd_build_info(flow, ovs_header->dp_ifindex,
+ info, OVS_FLOW_CMD_NEW, false);
} else {
/* We found a matching flow. */
/* Bail out if we're not allowed to modify an existing flow.
@@ -897,8 +908,9 @@ static int ovs_flow_cmd_new_or_set(struct sk_buff *skb,
struct genl_info *info)
rcu_assign_pointer(flow->sf_acts, acts);
ovs_nla_free_flow_actions(old_acts);
}
- reply = ovs_flow_cmd_build_info(flow, dp, info,
- OVS_FLOW_CMD_NEW, false);
+
+ reply = ovs_flow_cmd_build_info(flow, ovs_header->dp_ifindex,
+ info, OVS_FLOW_CMD_NEW, false);
/* Clear stats. */
if (a[OVS_FLOW_ATTR_CLEAR])
@@ -960,7 +972,8 @@ static int ovs_flow_cmd_get(struct sk_buff *skb, struct
genl_info *info)
goto unlock;
}
- reply = ovs_flow_cmd_build_info(flow, dp, info, OVS_FLOW_CMD_NEW, true);
+ reply = ovs_flow_cmd_build_info(flow, ovs_header->dp_ifindex, info,
+ OVS_FLOW_CMD_NEW, true);
if (IS_ERR(reply)) {
err = PTR_ERR(reply);
goto unlock;
@@ -1016,7 +1029,8 @@ static int ovs_flow_cmd_del(struct sk_buff *skb, struct
genl_info *info)
ovs_flow_tbl_remove(&dp->table, flow);
if (reply) {
- err = ovs_flow_cmd_fill_info(flow, dp, reply, info->snd_portid,
+ err = ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex,
+ reply, info->snd_portid,
info->snd_seq, 0,
OVS_FLOW_CMD_DEL);
BUG_ON(err < 0);
@@ -1057,7 +1071,7 @@ static int ovs_flow_cmd_dump(struct sk_buff *skb, struct
netlink_callback *cb)
if (!flow)
break;
- if (ovs_flow_cmd_fill_info(flow, dp, skb,
+ if (ovs_flow_cmd_fill_info(flow, ovs_header->dp_ifindex, skb,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, NLM_F_MULTI,
OVS_FLOW_CMD_NEW) < 0)
diff --git a/datapath/flow.c b/datapath/flow.c
index 5d1d2f2..6d7c3b5 100644
--- a/datapath/flow.c
+++ b/datapath/flow.c
@@ -123,8 +123,10 @@ unlock:
spin_unlock(&stats->lock);
}
-/* Called with ovs_mutex. */
-void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
+/* Must be called with rcu_read_lock or ovs_mutex if 'flow' is in the flow
+ * table. */
+void ovs_flow_stats_get(const struct sw_flow *flow,
+ struct ovs_flow_stats *ovs_stats,
unsigned long *used, __be16 *tcp_flags)
{
int node;
diff --git a/datapath/flow.h b/datapath/flow.h
index 5587577..25eba04 100644
--- a/datapath/flow.h
+++ b/datapath/flow.h
@@ -183,7 +183,7 @@ struct arp_eth_header {
} __packed;
void ovs_flow_stats_update(struct sw_flow *flow, struct sk_buff *skb);
-void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *stats,
+void ovs_flow_stats_get(const struct sw_flow *, struct ovs_flow_stats *,
unsigned long *used, __be16 *tcp_flags);
void ovs_flow_stats_clear(struct sw_flow *flow);
u64 ovs_flow_used_time(unsigned long flow_jiffies);
--
1.7.10.4
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