[net 1/1] tipc: tipc clang warning

[net 1/1] tipc: tipc clang warning

[Jon Maloy]

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>
---
 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 2dc4919..dd3b6dc 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -817,10 +817,10 @@ 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;
@@ -844,7 +844,8 @@ 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);
 }
 
-- 
2.1.4

Re: [net 1/1] tipc: tipc clang warning

[David Miller]

From: Jon Maloy <jon.maloy@ericsson.com>
Date: Fri, 22 Mar 2019 15:03:51 +0100

> 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>

Applied.