Merge branch 'drop_monitor-Convert-to-use-devlink-tracepoint'

Ido Schimmel says:

====================
drop_monitor: Convert to use devlink tracepoint

Drop monitor is able to monitor both software and hardware originated
drops. Software drops are monitored by having drop monitor register its
probe on the 'kfree_skb' tracepoint. Hardware originated drops are
monitored by having devlink call into drop monitor whenever it receives
a dropped packet from the underlying hardware.

This patch set converts drop monitor to monitor both software and
hardware originated drops in the same way - by registering its probe on
the relevant tracepoint.

In addition to drop monitor being more consistent, it is now also
possible to build drop monitor as module instead of as a builtin and
still monitor hardware originated drops. Initially, CONFIG_NET_DEVLINK
implied CONFIG_NET_DROP_MONITOR, but after commit def2fbffe62c
("kconfig: allow symbols implied by y to become m") we can have
CONFIG_NET_DEVLINK=y and CONFIG_NET_DROP_MONITOR=m and hardware
originated drops will not be monitored.

Patch set overview:

Patch #1 adds a tracepoint in devlink for trap reports.

Patch #2 prepares probe functions in drop monitor for the new
tracepoint.

Patch #3 converts drop monitor to use the new tracepoint.

Patches #4-#6 perform cleanups after the conversion.

Patch #7 adds a test case for drop monitor. Both software originated
drops and hardware originated drops (using netdevsim) are tested.

Tested:

| CONFIG_NET_DEVLINK | CONFIG_NET_DROP_MONITOR | Build | SW drops | HW drops |
| -------------------|-------------------------|-------|----------|----------|
|          y         |            y            |   v   |     v    |     v    |
|          y         |            m            |   v   |     v    |     v    |
|          y         |            n            |   v   |     x    |     x    |
|          n         |            y            |   v   |     v    |     x    |
|          n         |            m            |   v   |     v    |     x    |
|          n         |            n            |   v   |     x    |     x    |
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 53 insertions, 36 deletions

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 7339bf9ba6b4..1c286e9a3590 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -625,6 +625,22 @@ struct devlink_health_reporter_ops {
 };
 
 /**
+ * struct devlink_trap_metadata - Packet trap metadata.
+ * @trap_name: Trap name.
+ * @trap_group_name: Trap group name.
+ * @input_dev: Input netdevice.
+ * @fa_cookie: Flow action user cookie.
+ * @trap_type: Trap type.
+ */
+struct devlink_trap_metadata {
+	const char *trap_name;
+	const char *trap_group_name;
+	struct net_device *input_dev;
+	const struct flow_action_cookie *fa_cookie;
+	enum devlink_trap_type trap_type;
+};
+
+/**
  * struct devlink_trap_policer - Immutable packet trap policer attributes.
  * @id: Policer identifier.
  * @init_rate: Initial rate in packets / sec.
diff --git a/include/net/drop_monitor.h b/include/net/drop_monitor.h
deleted file mode 100644
index 3f5b6ddb3179..000000000000
--- a/include/net/drop_monitor.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-
-#ifndef _NET_DROP_MONITOR_H_
-#define _NET_DROP_MONITOR_H_
-
-#include <linux/ktime.h>
-#include <linux/netdevice.h>
-#include <linux/skbuff.h>
-#include <net/flow_offload.h>
-
-/**
- * struct net_dm_hw_metadata - Hardware-supplied packet metadata.
- * @trap_group_name: Hardware trap group name.
- * @trap_name: Hardware trap name.
- * @input_dev: Input netdevice.
- * @fa_cookie: Flow action user cookie.
- */
-struct net_dm_hw_metadata {
-	const char *trap_group_name;
-	const char *trap_name;
-	struct net_device *input_dev;
-	const struct flow_action_cookie *fa_cookie;
-};
-
-#if IS_REACHABLE(CONFIG_NET_DROP_MONITOR)
-void net_dm_hw_report(struct sk_buff *skb,
-		      const struct net_dm_hw_metadata *hw_metadata);
-#else
-static inline void
-net_dm_hw_report(struct sk_buff *skb,
-		 const struct net_dm_hw_metadata *hw_metadata)
-{
-}
-#endif
-
-#endif /* _NET_DROP_MONITOR_H_ */
diff --git a/include/trace/events/devlink.h b/include/trace/events/devlink.h
index 6f60a78d9a7e..44d8e2981065 100644
--- a/include/trace/events/devlink.h
+++ b/include/trace/events/devlink.h
@@ -171,6 +171,43 @@ TRACE_EVENT(devlink_health_reporter_state_update,
 		  __entry->new_state)
 );
 
+/*
+ * Tracepoint for devlink packet trap:
+ */
+TRACE_EVENT(devlink_trap_report,
+	TP_PROTO(const struct devlink *devlink, struct sk_buff *skb,
+		 const struct devlink_trap_metadata *metadata),
+
+	TP_ARGS(devlink, skb, metadata),
+
+	TP_STRUCT__entry(
+		__string(bus_name, devlink->dev->bus->name)
+		__string(dev_name, dev_name(devlink->dev))
+		__string(driver_name, devlink->dev->driver->name)
+		__string(trap_name, metadata->trap_name)
+		__string(trap_group_name, metadata->trap_group_name)
+		__dynamic_array(char, input_dev_name, IFNAMSIZ)
+	),
+
+	TP_fast_assign(
+		struct net_device *input_dev = metadata->input_dev;
+
+		__assign_str(bus_name, devlink->dev->bus->name);
+		__assign_str(dev_name, dev_name(devlink->dev));
+		__assign_str(driver_name, devlink->dev->driver->name);
+		__assign_str(trap_name, metadata->trap_name);
+		__assign_str(trap_group_name, metadata->trap_group_name);
+		__assign_str(input_dev_name,
+			     (input_dev ? input_dev->name : "NULL"));
+	),
+
+	TP_printk("bus_name=%s dev_name=%s driver_name=%s trap_name=%s "
+		  "trap_group_name=%s input_dev_name=%s", __get_str(bus_name),
+		  __get_str(dev_name), __get_str(driver_name),
+		  __get_str(trap_name), __get_str(trap_group_name),
+		  __get_str(input_dev_name))
+);
+
 #endif /* _TRACE_DEVLINK_H */
 
 /* This part must be outside protection */