[netdevice] Retain and report detailed error breakdowns

netdev_rx_err() and netdev_tx_complete_err() get passed the error
code, but currently use it only in debug messages.

Retain error numbers and frequencey counts for up to
NETDEV_MAX_UNIQUE_ERRORS (4) different errors for each of TX and RX.
This allows the "ifstat" command to report the reasons for TX/RX
errors in most cases, even in non-debug builds.

1 files changed, 42 insertions, 4 deletions

diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index 81c4ae88..e8587a9d 100644
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -46,6 +46,45 @@ static struct net_protocol net_protocols_end[0]
 struct list_head net_devices = LIST_HEAD_INIT ( net_devices );
 
 /**
+ * Record network device statistic
+ *
+ * @v stats		Network device statistics
+ * @v rc		Status code
+ */
+static void netdev_record_stat ( struct net_device_stats *stats, int rc ) {
+	struct net_device_error *error;
+	struct net_device_error *least_common_error;
+	unsigned int i;
+
+	/* If this is not an error, just update the good counter */
+	if ( rc == 0 ) {
+		stats->good++;
+		return;
+	}
+
+	/* Update the bad counter */
+	stats->bad++;
+
+	/* Locate the appropriate error record */
+	least_common_error = &stats->errors[0];
+	for ( i = 0 ; i < ( sizeof ( stats->errors ) /
+			    sizeof ( stats->errors[0] ) ) ; i++ ) {
+		error = &stats->errors[i];
+		/* Update matching record, if found */
+		if ( error->rc == rc ) {
+			error->count++;
+			return;
+		}
+		if ( error->count < least_common_error->count )
+			least_common_error = error;
+	}
+
+	/* Overwrite the least common error record */
+	least_common_error->rc = rc;
+	least_common_error->count = 1;
+}
+
+/**
  * Transmit raw packet via network device
  *
  * @v netdev		Network device
@@ -91,12 +130,11 @@ void netdev_tx_complete_err ( struct net_device *netdev,
 			      struct io_buffer *iobuf, int rc ) {
 
 	/* Update statistics counter */
+	netdev_record_stat ( &netdev->tx_stats, rc );
 	if ( rc == 0 ) {
-		netdev->stats.tx_ok++;
 		DBGC ( netdev, "NETDEV %p transmission %p complete\n",
 		       netdev, iobuf );
 	} else {
-		netdev->stats.tx_err++;
 		DBGC ( netdev, "NETDEV %p transmission %p failed: %s\n",
 		       netdev, iobuf, strerror ( rc ) );
 	}
@@ -158,7 +196,7 @@ void netdev_rx ( struct net_device *netdev, struct io_buffer *iobuf ) {
 	list_add_tail ( &iobuf->list, &netdev->rx_queue );
 
 	/* Update statistics counter */
-	netdev->stats.rx_ok++;
+	netdev_record_stat ( &netdev->rx_stats, 0 );
 }
 
 /**
@@ -183,7 +221,7 @@ void netdev_rx_err ( struct net_device *netdev,
 	free_iob ( iobuf );
 
 	/* Update statistics counter */
-	netdev->stats.rx_err++;
+	netdev_record_stat ( &netdev->rx_stats, rc );
 }
 
 /**