rxrpc: Improve skb tracing

Improve sk_buff tracing within AF_RXRPC by the following means:

 (1) Use an enum to note the event type rather than plain integers and use
     an array of event names rather than a big multi ?: list.

 (2) Distinguish Rx from Tx packets and account them separately.  This
     requires the call phase to be tracked so that we know what we might
     find in rxtx_buffer[].

 (3) Add a parameter to rxrpc_{new,see,get,free}_skb() to indicate the
     event type.

 (4) A pair of 'rotate' events are added to indicate packets that are about
     to be rotated out of the Rx and Tx windows.

 (5) A pair of 'lost' events are added, along with rxrpc_lose_skb() for
     packet loss injection recording.

Signed-off-by: David Howells <dhowells@redhat.com>
 

1 files changed, 38 insertions, 15 deletions

diff --git a/net/rxrpc/skbuff.c b/net/rxrpc/skbuff.c
index 620d9ccaf3c1..5154cbf7e540 100644
--- a/net/rxrpc/skbuff.c
+++ b/net/rxrpc/skbuff.c
@@ -18,55 +18,77 @@
 #include <net/af_rxrpc.h>
 #include "ar-internal.h"
 
+#define select_skb_count(op) (op >= rxrpc_skb_tx_cleaned ? &rxrpc_n_tx_skbs : &rxrpc_n_rx_skbs)
+
 /*
- * Note the existence of a new-to-us socket buffer (allocated or dequeued).
+ * Note the allocation or reception of a socket buffer.
  */
-void rxrpc_new_skb(struct sk_buff *skb)
+void rxrpc_new_skb(struct sk_buff *skb, enum rxrpc_skb_trace op)
 {
 	const void *here = __builtin_return_address(0);
-	int n = atomic_inc_return(&rxrpc_n_skbs);
-	trace_rxrpc_skb(skb, 0, atomic_read(&skb->users), n, here);
+	int n = atomic_inc_return(select_skb_count(op));
+	trace_rxrpc_skb(skb, op, atomic_read(&skb->users), n, here);
 }
 
 /*
  * Note the re-emergence of a socket buffer from a queue or buffer.
  */
-void rxrpc_see_skb(struct sk_buff *skb)
+void rxrpc_see_skb(struct sk_buff *skb, enum rxrpc_skb_trace op)
 {
 	const void *here = __builtin_return_address(0);
 	if (skb) {
-		int n = atomic_read(&rxrpc_n_skbs);
-		trace_rxrpc_skb(skb, 1, atomic_read(&skb->users), n, here);
+		int n = atomic_read(select_skb_count(op));
+		trace_rxrpc_skb(skb, op, atomic_read(&skb->users), n, here);
 	}
 }
 
 /*
  * Note the addition of a ref on a socket buffer.
  */
-void rxrpc_get_skb(struct sk_buff *skb)
+void rxrpc_get_skb(struct sk_buff *skb, enum rxrpc_skb_trace op)
 {
 	const void *here = __builtin_return_address(0);
-	int n = atomic_inc_return(&rxrpc_n_skbs);
-	trace_rxrpc_skb(skb, 2, atomic_read(&skb->users), n, here);
+	int n = atomic_inc_return(select_skb_count(op));
+	trace_rxrpc_skb(skb, op, atomic_read(&skb->users), n, here);
 	skb_get(skb);
 }
 
 /*
  * Note the destruction of a socket buffer.
  */
-void rxrpc_free_skb(struct sk_buff *skb)
+void rxrpc_free_skb(struct sk_buff *skb, enum rxrpc_skb_trace op)
 {
 	const void *here = __builtin_return_address(0);
 	if (skb) {
 		int n;
 		CHECK_SLAB_OKAY(&skb->users);
-		n = atomic_dec_return(&rxrpc_n_skbs);
-		trace_rxrpc_skb(skb, 3, atomic_read(&skb->users), n, here);
+		n = atomic_dec_return(select_skb_count(op));
+		trace_rxrpc_skb(skb, op, atomic_read(&skb->users), n, here);
 		kfree_skb(skb);
 	}
 }
 
 /*
+ * Note the injected loss of a socket buffer.
+ */
+void rxrpc_lose_skb(struct sk_buff *skb, enum rxrpc_skb_trace op)
+{
+	const void *here = __builtin_return_address(0);
+	if (skb) {
+		int n;
+		CHECK_SLAB_OKAY(&skb->users);
+		if (op == rxrpc_skb_tx_lost) {
+			n = atomic_read(select_skb_count(op));
+			trace_rxrpc_skb(skb, op, atomic_read(&skb->users), n, here);
+		} else {
+			n = atomic_dec_return(select_skb_count(op));
+			trace_rxrpc_skb(skb, op, atomic_read(&skb->users), n, here);
+			kfree_skb(skb);
+		}
+	}
+}
+
+/*
  * Clear a queue of socket buffers.
  */
 void rxrpc_purge_queue(struct sk_buff_head *list)
@@ -74,8 +96,9 @@ void rxrpc_purge_queue(struct sk_buff_head *list)
 	const void *here = __builtin_return_address(0);
 	struct sk_buff *skb;
 	while ((skb = skb_dequeue((list))) != NULL) {
-		int n = atomic_dec_return(&rxrpc_n_skbs);
-		trace_rxrpc_skb(skb, 4, atomic_read(&skb->users), n, here);
+		int n = atomic_dec_return(select_skb_count(rxrpc_skb_rx_purged));
+		trace_rxrpc_skb(skb, rxrpc_skb_rx_purged,
+				atomic_read(&skb->users), n, here);
 		kfree_skb(skb);
 	}
 }