[RFC net-next] openvswitch: add trace points

Aaron Conole
2021-05-27T19:15:45Z

This makes openvswitch module use the event tracing framework
to log the upcall interface and action execution pipeline. When
using openvswitch as the packet forwarding engine, some types of
debugging are made possible simply by using the ovs-vswitchd's
ofproto/trace command. However, such a command has some
limitations:

1. When trying to trace packets that go through the CT action,
the state of the packet can't be determined, and probably
would be potentially wrong.

2. Deducing problem packets can sometimes be difficult as well
even if many of the flows are known

3. It's possible to use the openvswitch module even without
the ovs-vswitchd (although, not common use).

Introduce the event tracing points here to make it possible for
working through these problems in kernel space. The style is
copied from the mac80211 driver-trace / trace code for
consistency.

Signed-off-by: Aaron Conole <aconole@redhat.com>
---
net/openvswitch/Makefile | 3 +
net/openvswitch/actions.c | 4 +
net/openvswitch/datapath.c | 7 ++
net/openvswitch/openvswitch_trace.c | 10 ++
net/openvswitch/openvswitch_trace.h | 152 ++++++++++++++++++++++++++++
5 files changed, 176 insertions(+)
create mode 100644 net/openvswitch/openvswitch_trace.c
create mode 100644 net/openvswitch/openvswitch_trace.h

diff --git a/net/openvswitch/Makefile b/net/openvswitch/Makefile
index 41109c326f3a..28982630bef3 100644
--- a/net/openvswitch/Makefile
+++ b/net/openvswitch/Makefile
@@ -13,6 +13,7 @@ openvswitch-y := \
flow_netlink.o \
flow_table.o \
meter.o \
+ openvswitch_trace.o \
vport.o \
vport-internal_dev.o \
vport-netdev.o
@@ -24,3 +25,5 @@ endif
obj-$(CONFIG_OPENVSWITCH_VXLAN)+= vport-vxlan.o
obj-$(CONFIG_OPENVSWITCH_GENEVE)+= vport-geneve.o
obj-$(CONFIG_OPENVSWITCH_GRE) += vport-gre.o
+
+CFLAGS_openvswitch_trace.o = -I$(src)
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index d858ea580e43..62285453ca79 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -30,6 +30,7 @@
#include "conntrack.h"
#include "vport.h"
#include "flow_netlink.h"
+#include "openvswitch_trace.h"

struct deferred_action {
struct sk_buff *skb;
@@ -1242,6 +1243,9 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
a = nla_next(a, &rem)) {
int err = 0;

+ if (trace_openvswitch_probe_action_enabled())
+ trace_openvswitch_probe_action(dp, skb, key, a, rem);
+
switch (nla_type(a)) {
case OVS_ACTION_ATTR_OUTPUT: {
int port = nla_get_u32(a);
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 9d6ef6cb9b26..63f19a6ed472 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -43,6 +43,7 @@
#include "flow_table.h"
#include "flow_netlink.h"
#include "meter.h"
+#include "openvswitch_trace.h"
#include "vport-internal_dev.h"
#include "vport-netdev.h"

@@ -275,6 +276,12 @@ int ovs_dp_upcall(struct datapath *dp, struct sk_buff *skb,
struct dp_stats_percpu *stats;
int err;

+ if (trace_openvswitch_probe_userspace_enabled()) {
+ struct sw_flow_key ukey = *key;
+
+ trace_openvswitch_probe_userspace(dp, skb, &ukey, upcall_info);
+ }
+
if (upcall_info->portid == 0) {
err = -ENOTCONN;
goto err;
diff --git a/net/openvswitch/openvswitch_trace.c b/net/openvswitch/openvswitch_trace.c
new file mode 100644
index 000000000000..62c5f7d6f023
--- /dev/null
+++ b/net/openvswitch/openvswitch_trace.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+/* bug in tracepoint.h, it should include this */
+#include <linux/module.h>
+
+/* sparse isn't too happy with all macros... */
+#ifndef __CHECKER__
+#define CREATE_TRACE_POINTS
+#include "openvswitch_trace.h"
+
+#endif
diff --git a/net/openvswitch/openvswitch_trace.h b/net/openvswitch/openvswitch_trace.h
new file mode 100644
index 000000000000..1b350306f622
--- /dev/null
+++ b/net/openvswitch/openvswitch_trace.h
@@ -0,0 +1,152 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM openvswitch
+
+#if !defined(_TRACE_OPENVSWITCH_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_OPENVSWITCH_H
+
+#include <linux/tracepoint.h>
+
+#include "datapath.h"
+
+TRACE_EVENT(openvswitch_probe_action,
+
+ TP_PROTO(struct datapath *dp, struct sk_buff *skb,
+ struct sw_flow_key *key, const struct nlattr *a, int rem),
+
+ TP_ARGS(dp, skb, key, a, rem),
+
+ TP_STRUCT__entry(
+ __field( void *, dpaddr )
+ __string( dp_name, ovs_dp_name(dp) )
+ __string( dev_name, skb->dev->name )
+ __field( void *, skbaddr )
+ __field( unsigned int, len )
+ __field( unsigned int, data_len )
+ __field( unsigned int, truesize )
+ __field( u8, nr_frags )
+ __field( u16, gso_size )
+ __field( u16, gso_type )
+ __field( u32, ovs_flow_hash )
+ __field( u32, recirc_id )
+ __field( void *, keyaddr )
+ __field( u16, key_eth_type )
+ __field( u8, key_ct_state )
+ __field( u8, key_ct_orig_proto )
+ __field( unsigned int, flow_key_valid )
+ __field( u8, action_type )
+ __field( unsigned int, action_len )
+ __field( void *, action_data )
+ __field( u8, is_last )
+ ),
+
+ TP_fast_assign(
+ __entry->dpaddr = dp;
+ __assign_str(dp_name, ovs_dp_name(dp));
+ __assign_str(dev_name, skb->dev->name);
+ __entry->skbaddr = skb;
+ __entry->len = skb->len;
+ __entry->data_len = skb->data_len;
+ __entry->truesize = skb->truesize;
+ __entry->nr_frags = skb_shinfo(skb)->nr_frags;
+ __entry->gso_size = skb_shinfo(skb)->gso_size;
+ __entry->gso_type = skb_shinfo(skb)->gso_type;
+ __entry->ovs_flow_hash = key->ovs_flow_hash;
+ __entry->recirc_id = key->recirc_id;
+ __entry->keyaddr = key;
+ __entry->key_eth_type = key->eth.type;
+ __entry->key_ct_state = key->ct_state;
+ __entry->key_ct_orig_proto = key->ct_orig_proto;
+ __entry->flow_key_valid = !(key->mac_proto & SW_FLOW_KEY_INVALID);
+ __entry->action_type = nla_type(a);
+ __entry->action_len = nla_len(a);
+ __entry->action_data = nla_data(a);
+ __entry->is_last = nla_is_last(a, rem);
+ ),
+
+ TP_printk("dpaddr=%p dp_name=%s dev=%s skbaddr=%p len=%u data_len=%u truesize=%u nr_frags=%d gso_size=%d gso_type=%#x ovs_flow_hash=0x%08x recirc_id=0x%08x keyaddr=%p eth_type=0x%04x ct_state=%02x ct_orig_proto=%02x flow_key_valid=%d action_type=%u action_len=%u action_data=%p is_last=%d",
+ __entry->dpaddr, __get_str(dp_name), __get_str(dev_name),
+ __entry->skbaddr, __entry->len, __entry->data_len,
+ __entry->truesize, __entry->nr_frags, __entry->gso_size,
+ __entry->gso_type, __entry->ovs_flow_hash,
+ __entry->recirc_id, __entry->keyaddr, __entry->key_eth_type,
+ __entry->key_ct_state, __entry->key_ct_orig_proto,
+ __entry->flow_key_valid,
+ __entry->action_type, __entry->action_len,
+ __entry->action_data, __entry->is_last)
+);
+
+TRACE_EVENT(openvswitch_probe_userspace,
+
+ TP_PROTO(struct datapath *dp, struct sk_buff *skb,
+ struct sw_flow_key *key,
+ const struct dp_upcall_info *upcall_info),
+
+ TP_ARGS(dp, skb, key, upcall_info),
+
+ TP_STRUCT__entry(
+ __field( void *, dpaddr )
+ __string( dp_name, ovs_dp_name(dp) )
+ __string( dev_name, skb->dev->name )
+ __field( void *, skbaddr )
+ __field( unsigned int, len )
+ __field( unsigned int, data_len )
+ __field( unsigned int, truesize )
+ __field( u8, nr_frags )
+ __field( u16, gso_size )
+ __field( u16, gso_type )
+ __field( u32, ovs_flow_hash )
+ __field( u32, recirc_id )
+ __field( void *, keyaddr )
+ __field( u16, key_eth_type )
+ __field( u8, key_ct_state )
+ __field( u8, key_ct_orig_proto )
+ __field( unsigned int, flow_key_valid )
+ __field( u8, upcall_cmd )
+ __field( u32, upcall_port )
+ __field( u16, upcall_mru )
+ ),
+
+ TP_fast_assign(
+ __entry->dpaddr = dp;
+ __assign_str(dp_name, ovs_dp_name(dp));
+ __assign_str(dev_name, skb->dev->name);
+ __entry->skbaddr = skb;
+ __entry->len = skb->len;
+ __entry->data_len = skb->data_len;
+ __entry->truesize = skb->truesize;
+ __entry->nr_frags = skb_shinfo(skb)->nr_frags;
+ __entry->gso_size = skb_shinfo(skb)->gso_size;
+ __entry->gso_type = skb_shinfo(skb)->gso_type;
+ __entry->ovs_flow_hash = key->ovs_flow_hash;
+ __entry->recirc_id = key->recirc_id;
+ __entry->keyaddr = key;
+ __entry->key_eth_type = key->eth.type;
+ __entry->key_ct_state = key->ct_state;
+ __entry->key_ct_orig_proto = key->ct_orig_proto;
+ __entry->flow_key_valid = !(key->mac_proto & SW_FLOW_KEY_INVALID);
+ __entry->upcall_cmd = upcall_info->cmd;
+ __entry->upcall_port = upcall_info->portid;
+ __entry->upcall_mru = upcall_info->mru;
+ ),
+
+ TP_printk("dpaddr=%p dp_name=%s dev=%s skbaddr=%p len=%u data_len=%u truesize=%u nr_frags=%d gso_size=%d gso_type=%#x ovs_flow_hash=0x%08x recirc_id=0x%08x keyaddr=%p eth_type=0x%04x ct_state=%02x ct_orig_proto=%02x flow_key_valid=%d upcall_cmd=%u upcall_port=%u upcall_mru=%u",
+ __entry->dpaddr, __get_str(dp_name), __get_str(dev_name),
+ __entry->skbaddr, __entry->len, __entry->data_len,
+ __entry->truesize, __entry->nr_frags, __entry->gso_size,
+ __entry->gso_type, __entry->ovs_flow_hash,
+ __entry->recirc_id, __entry->keyaddr, __entry->key_eth_type,
+ __entry->key_ct_state, __entry->key_ct_orig_proto,
+ __entry->flow_key_valid,
+ __entry->upcall_cmd, __entry->upcall_port,
+ __entry->upcall_mru)
+);
+
+#endif /* _TRACE_OPENVSWITCH_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE openvswitch_trace
+#include <trace/define_trace.h>
--
2.31.1