dropmon: add ability to detect when hardware dropsrxpackets

Patch to add the ability to detect drops in hardware interfaces via dropwatch.
Adds a tracepoint to net_rx_action to signal everytime a napi instance is
polled.  The dropmon code then periodically checks to see if the rx_frames
counter has changed, and if so, adds a drop notification to the netlink
protocol, using the reserved all-0's vector to indicate the drop location was in
hardware, rather than somewhere in the code.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

 include/linux/net_dropmon.h |    8 ++
 include/trace/napi.h        |   11 +++
 net/core/dev.c              |    5 +
 net/core/drop_monitor.c     |  124 ++++++++++++++++++++++++++++++++++++++++++--
 net/core/net-traces.c       |    4 +
 net/core/netpoll.c          |    2
 6 files changed, 149 insertions(+), 5 deletions(-)
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/net_dropmon.h b/include/linux/net_dropmon.h
index 0217fb81a630..e8a8b5c50ed0 100644
--- a/include/linux/net_dropmon.h
+++ b/include/linux/net_dropmon.h
@@ -2,12 +2,20 @@
 #define __NET_DROPMON_H
 
 #include <linux/netlink.h>
+#include <linux/types.h>
 
 struct net_dm_drop_point {
         __u8 pc[8];
         __u32 count;
 };
 
+#define is_drop_point_hw(x) do {\
+        int ____i, ____j;\
+        for (____i = 0; ____i < 8; i ____i++)\
+                ____j |= x[____i];\
+        ____j;\
+} while (0)
+
 #define NET_DM_CFG_VERSION  0
 #define NET_DM_CFG_ALERT_COUNT  1
 #define NET_DM_CFG_ALERT_DELAY 2
diff --git a/include/trace/napi.h b/include/trace/napi.h
new file mode 100644
index 000000000000..a8989c4547e7
--- /dev/null
+++ b/include/trace/napi.h
@@ -0,0 +1,11 @@
+#ifndef _TRACE_NAPI_H_
+#define _TRACE_NAPI_H_
+
+#include <linux/netdevice.h>
+#include <linux/tracepoint.h>
+
+DECLARE_TRACE(napi_poll,
+        TP_PROTO(struct napi_struct *napi),
+        TP_ARGS(napi));
+
+#endif