xen-netback: Add stat counters for zerocopy

These counters help determine how often the buffers had to be copied. Also
they help find out if packets are leaked, as if "sent != success + fail",
there are probably packets never freed up properly.

NOTE: if bisect brought you here, you should apply the series up until
"xen-netback: Timeout packets in RX path", otherwise Windows guests can't work
properly and malicious guests can block other guests by not releasing their sent
packets.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 1fe9fe523cc8..44df8581b4d7 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -238,6 +238,21 @@ static const struct xenvif_stat {
                 "rx_gso_checksum_fixup",
                 offsetof(struct xenvif, rx_gso_checksum_fixup)
         },
+        /* If (sent != success + fail), there are probably packets never
+         * freed up properly!
+         */
+        {
+                "tx_zerocopy_sent",
+                offsetof(struct xenvif, tx_zerocopy_sent),
+        },
+        {
+                "tx_zerocopy_success",
+                offsetof(struct xenvif, tx_zerocopy_success),
+        },
+        {
+                "tx_zerocopy_fail",
+                offsetof(struct xenvif, tx_zerocopy_fail)
+        },
 };
 
 static int xenvif_get_sset_count(struct net_device *dev, int string_set)