[PATCH] tcp: Suppress false positive cppcheck warning in tcp_update_seqack_wnd()

[PATCH] tcp: Suppress false positive cppcheck warning in tcp_update_seqack_wnd()

[Laurent Vivier]

Cppcheck doesn't track that tinfo is reassigned to &tinfo_new when NULL,
leading to a false uninitvar warning at line 1099. Add inline suppression.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 tcp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tcp.c b/tcp.c
index 17fda5dcd7db..8dabfd3042d2 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1132,6 +1132,7 @@ int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn,
 				return 0;
 		}
 
+		/* cppcheck-suppress uninitvar */
 		if ((unsigned)SNDBUF_GET(conn) > (long long)tinfo->tcpi_rtt *
 						 tinfo->tcpi_delivery_rate /
 						 1000 / 1000 *
-- 
2.51.1

Re: [PATCH] tcp: Suppress false positive cppcheck warning in tcp_update_seqack_wnd()

[David Gibson]

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On Tue, Dec 09, 2025 at 02:49:04PM +0100, Laurent Vivier wrote:
> Cppcheck doesn't track that tinfo is reassigned to &tinfo_new when NULL,
> leading to a false uninitvar warning at line 1099. Add inline
> suppression.

I think this is the same cppcheck bug as I encountered, a dozen or so
lines below this.  See
	https://sourceforge.net/p/cppcheck/discussion/general/thread/fecde59085/
and/or
	https://trac.cppcheck.net/ticket/14191

> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  tcp.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tcp.c b/tcp.c
> index 17fda5dcd7db..8dabfd3042d2 100644
> --- a/tcp.c
> +++ b/tcp.c
> @@ -1132,6 +1132,7 @@ int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn,
>  				return 0;
>  		}
>  
> +		/* cppcheck-suppress uninitvar */

Like the other case, I think we'll need unmatchedSuppression here, or
we'll get the unmatched suppression warning once using a fixed version
of cppcheck.  Possibly also with earlier cppcheck versions that didn't
trip on this.

>  		if ((unsigned)SNDBUF_GET(conn) > (long long)tinfo->tcpi_rtt *
>  						 tinfo->tcpi_delivery_rate /
>  						 1000 / 1000 *
> -- 
> 2.51.1
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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