Commit 1bb332af authored by Zoltan Kiss's avatar Zoltan Kiss Committed by David S. Miller
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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
Signed-off-by: default avatarZoltan Kiss <>
Signed-off-by: default avatarDavid S. Miller <>
parent 62bad319
......@@ -179,6 +179,9 @@ struct xenvif {
/* Statistics */
unsigned long rx_gso_checksum_fixup;
unsigned long tx_zerocopy_sent;
unsigned long tx_zerocopy_success;
unsigned long tx_zerocopy_fail;
/* Miscellaneous private stuff. */
struct net_device *dev;
......@@ -238,6 +238,21 @@ static const struct xenvif_stat {
offsetof(struct xenvif, rx_gso_checksum_fixup)
/* If (sent != success + fail), there are probably packets never
* freed up properly!
offsetof(struct xenvif, tx_zerocopy_sent),
offsetof(struct xenvif, tx_zerocopy_success),
offsetof(struct xenvif, tx_zerocopy_fail)
static int xenvif_get_sset_count(struct net_device *dev, int string_set)
......@@ -1323,8 +1323,10 @@ static int xenvif_tx_submit(struct xenvif *vif)
* do a skb_copy_ubufs while we are still in control of the
* skb. E.g. the __pskb_pull_tail earlier can do such thing.
if (skb_shinfo(skb)->destructor_arg)
if (skb_shinfo(skb)->destructor_arg) {
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
......@@ -1364,6 +1366,11 @@ void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
if (likely(zerocopy_success))
static inline void xenvif_tx_dealloc_action(struct xenvif *vif)
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