Re: [PATCH net-next v6 8/10] xen-netback: Add stat counters for frag_list skbs

From: Zoltan Kiss
Date: Thu Mar 06 2014 - 07:42:31 EST


On 05/03/14 12:35, Wei Liu wrote:
On Tue, Mar 04, 2014 at 10:32:19PM +0000, Zoltan Kiss wrote:
These counters help determine how often the guest sends a packet with more
than MAX_SKB_FRAGS frags.

NOTE: if bisect brought you here, you should apply the series up until #9,
otherwise malicious guests can block other guests by not releasing their sent
packets.

Signed-off-by: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>
---
drivers/net/xen-netback/common.h | 1 +
drivers/net/xen-netback/interface.c | 7 +++++++
drivers/net/xen-netback/netback.c | 1 +
3 files changed, 9 insertions(+)

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index eac171e..d8a2298 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -170,6 +170,7 @@ struct xenvif {
unsigned long tx_zerocopy_sent;
unsigned long tx_zerocopy_success;
unsigned long tx_zerocopy_fail;
+ unsigned long tx_frag_overflow;

/* Miscellaneous private stuff. */
struct net_device *dev;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index adfed30..ba5be2f 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -252,6 +252,13 @@ static const struct xenvif_stat {
"tx_zerocopy_fail",
offsetof(struct xenvif, tx_zerocopy_fail)
},
+ /* Number of packets exceeding MAX_SKB_FRAG slots. You should use
+ * a guest with the same MAX_SKB_FRAG
+ */
+ {
+ "tx_frag_overflow",
+ offsetof(struct xenvif, tx_frag_overflow)
+ },

This patch break bisection with a cause different than "unable to handle
too many frags", because previous patch makes use of this
tx_frag_overflow. It's harmless to merge this one into previous one.
Ok


};

static int xenvif_get_sset_count(struct net_device *dev, int
string_set)

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