* Compiler warning - ipv4 fib_trie
@ 2019-02-04 11:55 Koen Vandeputte
2019-02-05 2:53 ` David Ahern
0 siblings, 1 reply; 2+ messages in thread
From: Koen Vandeputte @ 2019-02-04 11:55 UTC (permalink / raw)
To: netdev
Hi All,
During compilation of kernel 4.14.96 and 5.0-rc5 I'm seeing following
warning:
net/ipv4/fib_trie.c: In function 'fib_trie_unmerge':
net/ipv4/fib_trie.c:1749:8: warning: 'local_tp' may be used
uninitialized in this function [-Wmaybe-uninitialized]
if (fib_insert_alias(lt, local_tp, local_l, new_fa,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NULL, l->key)) {
~~~~~~~~~~~~~
Code:
https://elixir.bootlin.com/linux/v5.0-rc5/source/net/ipv4/fib_trie.c#L1731
Looks like 'local_tp' should be NULL-ified
Thanks,
Koen
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: Compiler warning - ipv4 fib_trie
2019-02-04 11:55 Compiler warning - ipv4 fib_trie Koen Vandeputte
@ 2019-02-05 2:53 ` David Ahern
0 siblings, 0 replies; 2+ messages in thread
From: David Ahern @ 2019-02-05 2:53 UTC (permalink / raw)
To: Koen Vandeputte, netdev
On 2/4/19 3:55 AM, Koen Vandeputte wrote:
> Hi All,
>
> During compilation of kernel 4.14.96 and 5.0-rc5 I'm seeing following
> warning:
>
> net/ipv4/fib_trie.c: In function 'fib_trie_unmerge':
> net/ipv4/fib_trie.c:1749:8: warning: 'local_tp' may be used
> uninitialized in this function [-Wmaybe-uninitialized]
> if (fib_insert_alias(lt, local_tp, local_l, new_fa,
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> NULL, l->key)) {
> ~~~~~~~~~~~~~
>
> Code:
>
> https://elixir.bootlin.com/linux/v5.0-rc5/source/net/ipv4/fib_trie.c#L1731
>
> Looks like 'local_tp' should be NULL-ified
>
>
> Thanks,
>
> Koen
>
I believe that is a false positive. If you analyze the loop, local_tp is
set when local_l is NULL and it is set before the first use. I am
surprised the compiler can not track that. fib_find_node has 1 return
point and local_tp is set right before.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-02-04 11:55 Compiler warning - ipv4 fib_trie Koen Vandeputte
2019-02-05 2:53 ` David Ahern
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