core: add tracepoints for queueing skb to rcvbuf

This patch adds 2 tracepoints to get a status of a socket receive queue
and related parameter.

One tracepoint is added to sock_queue_rcv_skb. It records rcvbuf size
and its usage. The other tracepoint is added to __sk_mem_schedule and
it records limitations of memory for sockets and current usage.

By using these tracepoints we're able to know detailed reason why kernel
drop the packet.

Signed-off-by: Satoru Moriya <satoru.moriya@hds.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 0 deletions

diff --git a/net/core/net-traces.c b/net/core/net-traces.c
index 13aab64520ad..52380b1d552a 100644
--- a/net/core/net-traces.c
+++ b/net/core/net-traces.c
@@ -28,6 +28,7 @@
 #include <trace/events/skb.h>
 #include <trace/events/net.h>
 #include <trace/events/napi.h>
+#include <trace/events/sock.h>
 #include <trace/events/udp.h>
 
 EXPORT_TRACEPOINT_SYMBOL_GPL(kfree_skb);
diff --git a/net/core/sock.c b/net/core/sock.c
index 6e819780c232..76c403146750 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -128,6 +128,8 @@
 
 #include <linux/filter.h>
 
+#include <trace/events/sock.h>
+
 #ifdef CONFIG_INET
 #include <net/tcp.h>
 #endif
@@ -292,6 +294,7 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
             (unsigned)sk->sk_rcvbuf) {
                 atomic_inc(&sk->sk_drops);
+                trace_sock_rcvqueue_full(sk, skb);
                 return -ENOMEM;
         }
 
@@ -1736,6 +1739,8 @@ suppress_allocation:
                         return 1;
         }
 
+        trace_sock_exceed_buf_limit(sk, prot, allocated);
+
         /* Alas. Undo changes. */
         sk->sk_forward_alloc -= amt * SK_MEM_QUANTUM;
         atomic_long_sub(amt, prot->memory_allocated);