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>

diff --git a/include/trace/events/sock.h b/include/trace/events/sock.h
new file mode 100644 (file)
index 0000000..779abb9
--- /dev/null
+++ b/include/trace/events/sock.h
@@ -0,0 +1,68 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sock
+
+#if !defined(_TRACE_SOCK_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SOCK_H
+
+#include <net/sock.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(sock_rcvqueue_full,
+
+       TP_PROTO(struct sock *sk, struct sk_buff *skb),
+
+       TP_ARGS(sk, skb),
+
+       TP_STRUCT__entry(
+               __field(int, rmem_alloc)
+               __field(unsigned int, truesize)
+               __field(int, sk_rcvbuf)
+       ),
+
+       TP_fast_assign(
+               __entry->rmem_alloc = atomic_read(&sk->sk_rmem_alloc);
+               __entry->truesize   = skb->truesize;
+               __entry->sk_rcvbuf  = sk->sk_rcvbuf;
+       ),
+
+       TP_printk("rmem_alloc=%d truesize=%u sk_rcvbuf=%d",
+               __entry->rmem_alloc, __entry->truesize, __entry->sk_rcvbuf)
+);
+
+TRACE_EVENT(sock_exceed_buf_limit,
+
+       TP_PROTO(struct sock *sk, struct proto *prot, long allocated),
+
+       TP_ARGS(sk, prot, allocated),
+
+       TP_STRUCT__entry(
+               __array(char, name, 32)
+               __field(long *, sysctl_mem)
+               __field(long, allocated)
+               __field(int, sysctl_rmem)
+               __field(int, rmem_alloc)
+       ),
+
+       TP_fast_assign(
+               strncpy(__entry->name, prot->name, 32);
+               __entry->sysctl_mem = prot->sysctl_mem;
+               __entry->allocated = allocated;
+               __entry->sysctl_rmem = prot->sysctl_rmem[0];
+               __entry->rmem_alloc = atomic_read(&sk->sk_rmem_alloc);
+       ),
+
+       TP_printk("proto:%s sysctl_mem=%ld,%ld,%ld allocated=%ld "
+               "sysctl_rmem=%d rmem_alloc=%d",
+               __entry->name,
+               __entry->sysctl_mem[0],
+               __entry->sysctl_mem[1],
+               __entry->sysctl_mem[2],
+               __entry->allocated,
+               __entry->sysctl_rmem,
+               __entry->rmem_alloc)
+);
+
+#endif /* _TRACE_SOCK_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

diff --git a/net/core/net-traces.c b/net/core/net-traces.c
index 13aab64520adc4a9fa1590ad646960d6517d7605..52380b1d552aded06478f6ac684ba0eab2a9d506 100644 (file)
--- 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 6e819780c23252b3387c1b2daec25a261fa1f2fb..76c40314675038f35669ca3642fcf73fbce89d67 100644 (file)
--- 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);