From 1159d4b496f57d5b8ee27c8b90b9d01c332e2e11 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 30 Mar 2018 21:05:38 +0100
Subject: rxrpc: Add a tracepoint to track rxrpc_peer refcounting

Add a tracepoint to track reference counting on the rxrpc_peer struct.

Signed-off-by: David Howells <dhowells@redhat.com>
---
 net/rxrpc/ar-internal.h | 23 +++--------------
 net/rxrpc/peer_event.c  |  2 +-
 net/rxrpc/peer_object.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 68 insertions(+), 22 deletions(-)

(limited to 'net/rxrpc')

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index d40d54b78567..c46583bc255d 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -1041,25 +1041,10 @@ struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *,
 struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *, gfp_t);
 struct rxrpc_peer *rxrpc_lookup_incoming_peer(struct rxrpc_local *,
 					      struct rxrpc_peer *);
-
-static inline struct rxrpc_peer *rxrpc_get_peer(struct rxrpc_peer *peer)
-{
-	atomic_inc(&peer->usage);
-	return peer;
-}
-
-static inline
-struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *peer)
-{
-	return atomic_inc_not_zero(&peer->usage) ? peer : NULL;
-}
-
-extern void __rxrpc_put_peer(struct rxrpc_peer *peer);
-static inline void rxrpc_put_peer(struct rxrpc_peer *peer)
-{
-	if (peer && atomic_dec_and_test(&peer->usage))
-		__rxrpc_put_peer(peer);
-}
+struct rxrpc_peer *rxrpc_get_peer(struct rxrpc_peer *);
+struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *);
+void rxrpc_put_peer(struct rxrpc_peer *);
+void __rxrpc_queue_peer_error(struct rxrpc_peer *);
 
 /*
  * proc.c
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index d01eb9a06448..78c2f95d1f22 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -192,7 +192,7 @@ void rxrpc_error_report(struct sock *sk)
 	rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 
 	/* The ref we obtained is passed off to the work item */
-	rxrpc_queue_work(&peer->error_distributor);
+	__rxrpc_queue_peer_error(peer);
 	_leave("");
 }
 
diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index 94a6dbfcf129..a4a750aea1e5 100644
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -386,9 +386,54 @@ struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local,
 }
 
 /*
- * Discard a ref on a remote peer record.
+ * Get a ref on a peer record.
  */
-void __rxrpc_put_peer(struct rxrpc_peer *peer)
+struct rxrpc_peer *rxrpc_get_peer(struct rxrpc_peer *peer)
+{
+	const void *here = __builtin_return_address(0);
+	int n;
+
+	n = atomic_inc_return(&peer->usage);
+	trace_rxrpc_peer(peer, rxrpc_peer_got, n, here);
+	return peer;
+}
+
+/*
+ * Get a ref on a peer record unless its usage has already reached 0.
+ */
+struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *peer)
+{
+	const void *here = __builtin_return_address(0);
+
+	if (peer) {
+		int n = __atomic_add_unless(&peer->usage, 1, 0);
+		if (n > 0)
+			trace_rxrpc_peer(peer, rxrpc_peer_got, n + 1, here);
+		else
+			peer = NULL;
+	}
+	return peer;
+}
+
+/*
+ * Queue a peer record.  This passes the caller's ref to the workqueue.
+ */
+void __rxrpc_queue_peer_error(struct rxrpc_peer *peer)
+{
+	const void *here = __builtin_return_address(0);
+	int n;
+
+	n = atomic_read(&peer->usage);
+	if (rxrpc_queue_work(&peer->error_distributor))
+		trace_rxrpc_peer(peer, rxrpc_peer_queued_error, n, here);
+	else
+		rxrpc_put_peer(peer);
+}
+
+/*
+ * Discard a peer record.
+ */
+static void __rxrpc_put_peer(struct rxrpc_peer *peer)
 {
 	struct rxrpc_net *rxnet = peer->local->rxnet;
 
@@ -402,6 +447,22 @@ void __rxrpc_put_peer(struct rxrpc_peer *peer)
 	kfree_rcu(peer, rcu);
 }
 
+/*
+ * Drop a ref on a peer record.
+ */
+void rxrpc_put_peer(struct rxrpc_peer *peer)
+{
+	const void *here = __builtin_return_address(0);
+	int n;
+
+	if (peer) {
+		n = atomic_dec_return(&peer->usage);
+		trace_rxrpc_peer(peer, rxrpc_peer_put, n, here);
+		if (n == 0)
+			__rxrpc_put_peer(peer);
+	}
+}
+
 /**
  * rxrpc_kernel_get_peer - Get the peer address of a call
  * @sock: The socket on which the call is in progress.
-- 
cgit