net/mlx5e: Add trace point for neigh update

Allow tracing neigh state during neigh update task that is executed on
workqueue and is scheduled by neigh state change event.

Usage example:
 ># cd /sys/kernel/debug/tracing
 ># echo mlx5:mlx5e_rep_neigh_update >> set_event
 ># cat trace
    ...
    kworker/u48:7-2221  [009] ...1  1475.387435: mlx5e_rep_neigh_update:
netdev: ens1f0 MAC: 24:8a:07:9a:17:9a IPv4: 1.1.1.10 IPv6: ::ffff:1.1.1.10 neigh_connected=1

Added corresponding documentation in
    Documentation/networking/device-driver/mellanox/mlx5.rst
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Dmytro Linkin <dmitrolin@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

Documentation/networking/device_drivers/mellanox/mlx5.rst

@@ -258,3 +258,10 @@ tc and eswitch offloads tracepoints:
     $ cat /sys/kernel/debug/tracing/trace
     ...
     kworker/u48:4-8806  [009] ...1 55117.882428: mlx5e_tc_update_neigh_used_value: netdev: ens1f0 IPv4: 1.1.1.10 IPv6: ::ffff:1.1.1.10 neigh_used=1
+
+- mlx5e_rep_neigh_update: trace neigh update tasks scheduled due to neigh state change events::
+
+    $ echo mlx5:mlx5e_rep_neigh_update >> /sys/kernel/debug/tracing/set_event
+    $ cat /sys/kernel/debug/tracing/trace
+    ...
+    kworker/u48:7-2221  [009] ...1  1475.387435: mlx5e_rep_neigh_update: netdev: ens1f0 MAC: 24:8a:07:9a:17:9a IPv4: 1.1.1.10 IPv6: ::ffff:1.1.1.10 neigh_connected=1

drivers/net/ethernet/mellanox/mlx5/core/diag/en_rep_tracepoint.h

+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2019 Mellanox Technologies. */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mlx5
+
+#if !defined(_MLX5_EN_REP_TP_) || defined(TRACE_HEADER_MULTI_READ)
+#define _MLX5_EN_REP_TP_
+
+#include <linux/tracepoint.h>
+#include <linux/trace_seq.h>
+#include "en_rep.h"
+
+TRACE_EVENT(mlx5e_rep_neigh_update,
+	    TP_PROTO(const struct mlx5e_neigh_hash_entry *nhe, const u8 *ha,
+		     bool neigh_connected),
+	    TP_ARGS(nhe, ha, neigh_connected),
+	    TP_STRUCT__entry(__string(devname, nhe->m_neigh.dev->name)
+			     __array(u8, ha, ETH_ALEN)
+			     __array(u8, v4, 4)
+			     __array(u8, v6, 16)
+			     __field(bool, neigh_connected)
+			     ),
+	    TP_fast_assign(const struct mlx5e_neigh *mn = &nhe->m_neigh;
+			struct in6_addr *pin6;
+			__be32 *p32;
+
+			__assign_str(devname, mn->dev->name);
+			__entry->neigh_connected = neigh_connected;
+			memcpy(__entry->ha, ha, ETH_ALEN);
+
+			p32 = (__be32 *)__entry->v4;
+			pin6 = (struct in6_addr *)__entry->v6;
+			if (mn->family == AF_INET) {
+				*p32 = mn->dst_ip.v4;
+				ipv6_addr_set_v4mapped(*p32, pin6);
+			} else if (mn->family == AF_INET6) {
+				*pin6 = mn->dst_ip.v6;
+			}
+			),
+	    TP_printk("netdev: %s MAC: %pM IPv4: %pI4 IPv6: %pI6c neigh_connected=%d\n",
+		      __get_str(devname), __entry->ha,
+		      __entry->v4, __entry->v6, __entry->neigh_connected
+		      )
+);
+
+#endif /* _MLX5_EN_REP_TP_ */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ./diag
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE en_rep_tracepoint
+#include <trace/define_trace.h>

drivers/net/ethernet/mellanox/mlx5/core/en_rep.c

@@ -46,6 +46,8 @@
 #include "en/tc_tun.h"
 #include "fs_core.h"
 #include "lib/port_tun.h"
+#define CREATE_TRACE_POINTS
+#include "diag/en_rep_tracepoint.h"
 
 #define MLX5E_REP_PARAMS_DEF_LOG_SQ_SIZE \
         max(0x7, MLX5E_PARAMS_MINIMUM_LOG_SQ_SIZE)
@@ -657,6 +659,8 @@ static void mlx5e_rep_neigh_update(struct work_struct *work)
 
 	neigh_connected = (nud_state & NUD_VALID) && !dead;
 
+	trace_mlx5e_rep_neigh_update(nhe, ha, neigh_connected);
+
 	list_for_each_entry(e, &nhe->encap_list, encap_list) {
 		if (!mlx5e_encap_take(e))
 			continue;