From: Ido Schimmel <idosch@mellanox.com>
Date: Sun, 11 Aug 2019 10:35:50 +0300
Subject: drop_monitor: Add alert mode operations
Patch-mainline: v5.4-rc1
Git-commit: 28315f7999870bb56da236f6b4ffce63efcc7897
References: bsc#1154353

The next patch is going to add another alert mode in which the dropped
packet is notified to user space, instead of only a summary of recent
drops.

Abstract the differences between the modes by adding alert mode
operations. The operations are selected based on the currently
configured mode and associated with the probes and the work item just
before tracing starts.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/uapi/linux/net_dropmon.h |    9 +++++++++
 net/core/drop_monitor.c          |   38 ++++++++++++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 6 deletions(-)

--- a/include/uapi/linux/net_dropmon.h
+++ b/include/uapi/linux/net_dropmon.h
@@ -62,4 +62,13 @@ enum {
  * Our group identifiers
  */
 #define NET_DM_GRP_ALERT 1
+
+/**
+ * enum net_dm_alert_mode - Alert mode.
+ * @NET_DM_ALERT_MODE_SUMMARY: A summary of recent drops is sent to user space.
+ */
+enum net_dm_alert_mode {
+	NET_DM_ALERT_MODE_SUMMARY,
+};
+
 #endif
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -75,6 +75,16 @@ static int dm_delay = 1;
 static unsigned long dm_hw_check_delta = 2*HZ;
 static LIST_HEAD(hw_stats_list);
 
+static enum net_dm_alert_mode net_dm_alert_mode = NET_DM_ALERT_MODE_SUMMARY;
+
+struct net_dm_alert_ops {
+	void (*kfree_skb_probe)(void *ignore, struct sk_buff *skb,
+				void *location);
+	void (*napi_poll_probe)(void *ignore, struct napi_struct *napi,
+				int work, int budget);
+	void (*work_item_func)(struct work_struct *work);
+};
+
 static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
 {
 	size_t al;
@@ -241,10 +251,23 @@ static void trace_napi_poll_hit(void *ig
 	rcu_read_unlock();
 }
 
+static const struct net_dm_alert_ops net_dm_alert_summary_ops = {
+	.kfree_skb_probe	= trace_kfree_skb_hit,
+	.napi_poll_probe	= trace_napi_poll_hit,
+	.work_item_func		= send_dm_alert,
+};
+
+static const struct net_dm_alert_ops *net_dm_alert_ops_arr[] = {
+	[NET_DM_ALERT_MODE_SUMMARY]	= &net_dm_alert_summary_ops,
+};
+
 static int net_dm_trace_on_set(struct netlink_ext_ack *extack)
 {
+	const struct net_dm_alert_ops *ops;
 	int cpu, rc;
 
+	ops = net_dm_alert_ops_arr[net_dm_alert_mode];
+
 	if (!try_module_get(THIS_MODULE)) {
 		NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
 		return -ENODEV;
@@ -254,7 +277,7 @@ static int net_dm_trace_on_set(struct ne
 		struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
 		struct sk_buff *skb;
 
-		INIT_WORK(&data->dm_alert_work, send_dm_alert);
+		INIT_WORK(&data->dm_alert_work, ops->work_item_func);
 		timer_setup(&data->send_timer, sched_send_work, 0);
 		/* Allocate a new per-CPU skb for the summary alert message and
 		 * free the old one which might contain stale data from
@@ -264,13 +287,13 @@ static int net_dm_trace_on_set(struct ne
 		consume_skb(skb);
 	}
 
-	rc = register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
+	rc = register_trace_kfree_skb(ops->kfree_skb_probe, NULL);
 	if (rc) {
 		NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to kfree_skb() tracepoint");
 		goto err_module_put;
 	}
 
-	rc = register_trace_napi_poll(trace_napi_poll_hit, NULL);
+	rc = register_trace_napi_poll(ops->napi_poll_probe, NULL);
 	if (rc) {
 		NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to napi_poll() tracepoint");
 		goto err_unregister_trace;
@@ -279,7 +302,7 @@ static int net_dm_trace_on_set(struct ne
 	return 0;
 
 err_unregister_trace:
-	unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
+	unregister_trace_kfree_skb(ops->kfree_skb_probe, NULL);
 err_module_put:
 	module_put(THIS_MODULE);
 	return rc;
@@ -288,10 +311,13 @@ err_module_put:
 static void net_dm_trace_off_set(void)
 {
 	struct dm_hw_stat_delta *new_stat, *temp;
+	const struct net_dm_alert_ops *ops;
 	int cpu;
 
-	unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
-	unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
+	ops = net_dm_alert_ops_arr[net_dm_alert_mode];
+
+	unregister_trace_napi_poll(ops->napi_poll_probe, NULL);
+	unregister_trace_kfree_skb(ops->kfree_skb_probe, NULL);
 
 	tracepoint_synchronize_unregister();