net: core: devlink: add dropped stats traps field

Whenever query statistics is issued for trap, devlink subsystem
would also fill-in statistics 'dropped' field. This field indicates
the number of packets HW dropped and failed to report to the device driver,
and thus - to the devlink subsystem itself.
In case if device driver didn't register callback for hard drop
statistics querying, 'dropped' field will be omitted and not filled.
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -1347,6 +1347,16 @@ struct devlink_ops {
 				     const struct devlink_trap_group *group,
 				     enum devlink_trap_action action,
 				     struct netlink_ext_ack *extack);
+	/**
+	 * @trap_drop_counter_get: Trap drop counter get function.
+	 *
+	 * Should be used by device drivers to report number of packets
+	 * that have been dropped, and cannot be passed to the devlink
+	 * subsystem by the underlying device.
+	 */
+	int (*trap_drop_counter_get)(struct devlink *devlink,
+				     const struct devlink_trap *trap,
+				     u64 *p_drops);
 	/**
 	 * @trap_policer_init: Trap policer initialization function.
 	 *

net/core/devlink.c

@@ -7519,8 +7519,9 @@ static void devlink_trap_stats_read(struct devlink_stats __percpu *trap_stats,
 	}
 }
 
-static int devlink_trap_stats_put(struct sk_buff *msg,
-				  struct devlink_stats __percpu *trap_stats)
+static int
+devlink_trap_group_stats_put(struct sk_buff *msg,
+			     struct devlink_stats __percpu *trap_stats)
 {
 	struct devlink_stats stats;
 	struct nlattr *attr;
@@ -7548,6 +7549,50 @@ static int devlink_trap_stats_put(struct sk_buff *msg,
 	return -EMSGSIZE;
 }
 
+static int devlink_trap_stats_put(struct sk_buff *msg, struct devlink *devlink,
+				  const struct devlink_trap_item *trap_item)
+{
+	struct devlink_stats stats;
+	struct nlattr *attr;
+	u64 drops = 0;
+	int err;
+
+	if (devlink->ops->trap_drop_counter_get) {
+		err = devlink->ops->trap_drop_counter_get(devlink,
+							  trap_item->trap,
+							  &drops);
+		if (err)
+			return err;
+	}
+
+	devlink_trap_stats_read(trap_item->stats, &stats);
+
+	attr = nla_nest_start(msg, DEVLINK_ATTR_STATS);
+	if (!attr)
+		return -EMSGSIZE;
+
+	if (devlink->ops->trap_drop_counter_get &&
+	    nla_put_u64_64bit(msg, DEVLINK_ATTR_STATS_RX_DROPPED, drops,
+			      DEVLINK_ATTR_PAD))
+		goto nla_put_failure;
+
+	if (nla_put_u64_64bit(msg, DEVLINK_ATTR_STATS_RX_PACKETS,
+			      stats.rx_packets, DEVLINK_ATTR_PAD))
+		goto nla_put_failure;
+
+	if (nla_put_u64_64bit(msg, DEVLINK_ATTR_STATS_RX_BYTES,
+			      stats.rx_bytes, DEVLINK_ATTR_PAD))
+		goto nla_put_failure;
+
+	nla_nest_end(msg, attr);
+
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(msg, attr);
+	return -EMSGSIZE;
+}
+
 static int devlink_nl_trap_fill(struct sk_buff *msg, struct devlink *devlink,
 				const struct devlink_trap_item *trap_item,
 				enum devlink_command cmd, u32 portid, u32 seq,
@@ -7585,7 +7630,7 @@ static int devlink_nl_trap_fill(struct sk_buff *msg, struct devlink *devlink,
 	if (err)
 		goto nla_put_failure;
 
-	err = devlink_trap_stats_put(msg, trap_item->stats);
+	err = devlink_trap_stats_put(msg, devlink, trap_item);
 	if (err)
 		goto nla_put_failure;
 
@@ -7802,7 +7847,7 @@ devlink_nl_trap_group_fill(struct sk_buff *msg, struct devlink *devlink,
 			group_item->policer_item->policer->id))
 		goto nla_put_failure;
 
-	err = devlink_trap_stats_put(msg, group_item->stats);
+	err = devlink_trap_group_stats_put(msg, group_item->stats);
 	if (err)
 		goto nla_put_failure;