rxrpc: Use a tracepoint for skb accounting debugging

Use a tracepoint to log various skb accounting points to help in debugging
refcounting errors.

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

1 files changed, 62 insertions, 0 deletions

diff --git a/net/rxrpc/skbuff.c b/net/rxrpc/skbuff.c
index 06c51d4b622d..d28058a97bc1 100644
--- a/net/rxrpc/skbuff.c
+++ b/net/rxrpc/skbuff.c
@@ -163,3 +163,65 @@ void rxrpc_kernel_free_skb(struct sk_buff *skb)
 	rxrpc_free_skb(skb);
 }
 EXPORT_SYMBOL(rxrpc_kernel_free_skb);
+
+/*
+ * Note the existence of a new-to-us socket buffer (allocated or dequeued).
+ */
+void rxrpc_new_skb(struct sk_buff *skb)
+{
+	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);
+}
+
+/*
+ * Note the re-emergence of a socket buffer from a queue or buffer.
+ */
+void rxrpc_see_skb(struct sk_buff *skb)
+{
+	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);
+	}
+}
+
+/*
+ * Note the addition of a ref on a socket buffer.
+ */
+void rxrpc_get_skb(struct sk_buff *skb)
+{
+	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);
+	skb_get(skb);
+}
+
+/*
+ * Note the destruction of a socket buffer.
+ */
+void rxrpc_free_skb(struct sk_buff *skb)
+{
+	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);
+		kfree_skb(skb);
+	}
+}
+
+/*
+ * Clear a queue of socket buffers.
+ */
+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);
+		kfree_skb(skb);
+	}
+}