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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Nathan Chancellor <natechancellor@gmail.com>,
        Jon Maloy <jon.maloy@ericsson.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 271/639] tipc: tipc clang warning
Date:   Fri, 24 Jan 2020 10:27:21 +0100
Message-Id: <20200124093120.651508263@linuxfoundation.org>
In-Reply-To: <20200124093047.008739095@linuxfoundation.org>
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From: Jon Maloy <jon.maloy@ericsson.com>

[ Upstream commit 737889efe9713a0f20a75fd0de952841d9275e6b ]

When checking the code with clang -Wsometimes-uninitialized we get the
following warning:

if (!tipc_link_is_establishing(l)) {
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/tipc/node.c:847:46: note: uninitialized use occurs here
      tipc_bearer_xmit(n->net, bearer_id, &xmitq, maddr);

net/tipc/node.c:831:2: note: remove the 'if' if its condition is always
true
if (!tipc_link_is_establishing(l)) {
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/tipc/node.c:821:31: note: initialize the variable 'maddr' to silence
this warning
struct tipc_media_addr *maddr;

We fix this by initializing 'maddr' to NULL. For the matter of clarity,
we also test if 'xmitq' is non-empty before we use it and 'maddr'
further down in the  function. It will never happen that 'xmitq' is non-
empty at the same time as 'maddr' is NULL, so this is a sufficient test.

Fixes: 598411d70f85 ("tipc: make resetting of links non-atomic")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/tipc/node.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 32556f480a606..e67ffd1949272 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -810,10 +810,10 @@ static void __tipc_node_link_down(struct tipc_node *n, int *bearer_id,
 static void tipc_node_link_down(struct tipc_node *n, int bearer_id, bool delete)
 {
 	struct tipc_link_entry *le = &n->links[bearer_id];
+	struct tipc_media_addr *maddr = NULL;
 	struct tipc_link *l = le->link;
-	struct tipc_media_addr *maddr;
-	struct sk_buff_head xmitq;
 	int old_bearer_id = bearer_id;
+	struct sk_buff_head xmitq;
 
 	if (!l)
 		return;
@@ -835,7 +835,8 @@ static void tipc_node_link_down(struct tipc_node *n, int bearer_id, bool delete)
 	tipc_node_write_unlock(n);
 	if (delete)
 		tipc_mon_remove_peer(n->net, n->addr, old_bearer_id);
-	tipc_bearer_xmit(n->net, bearer_id, &xmitq, maddr);
+	if (!skb_queue_empty(&xmitq))
+		tipc_bearer_xmit(n->net, bearer_id, &xmitq, maddr);
 	tipc_sk_rcv(n->net, &le->inputq);
 }
 
-- 
2.20.1