tcp: Suppress knownConditionTrueFalse cppcheck false positive

cppcheck 2.10 reports:

tcp.c:1815:12: style: Condition 'wnd>prev_scaled' is always false [knownConditionTrueFalse]
  if ((wnd > prev_scaled && wnd * 99 / 100 < prev_scaled) ||
           ^
tcp.c:1808:8: note: Assignment 'wnd=((1<<(16+8))<(wnd))?(1<<(16+8)):(wnd)', assigned value is less than 1
 wnd = MIN(MAX_WINDOW, wnd);
       ^
tcp.c:1811:19: note: Assuming condition is false
  if (prev_scaled == wnd)
                  ^
tcp.c:1815:12: note: Condition 'wnd>prev_scaled' is always false
  if ((wnd > prev_scaled && wnd * 99 / 100 < prev_scaled) ||
           ^

but this is not actually the case: wnd is typically greater than 1,
and might very well be greater than prev_scaled as well.

I bisected this down to cppcheck commit b4d455df487c ("Fix 11349: FP
negativeIndex for clamped array index (#4627)") and reported findings
at https://github.com/danmar/cppcheck/pull/4627.

Suppress the warning for the moment being.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/tcp.c b/tcp.c
index 803c2c4..21c319d 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1812,6 +1812,15 @@ static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn,
 			return;
 
 		/* Discard +/- 1% updates to spare some syscalls. */
+		/* TODO: cppcheck, starting from commit b4d455df487c ("Fix
+		 * 11349: FP negativeIndex for clamped array index (#4627)"),
+		 * reports wnd > prev_scaled as always being true, see also:
+		 *
+		 *	https://github.com/danmar/cppcheck/pull/4627
+		 *
+		 * drop this suppression once that's resolved.
+		 */
+		/* cppcheck-suppress knownConditionTrueFalse */
 		if ((wnd > prev_scaled && wnd * 99 / 100 < prev_scaled) ||
 		    (wnd < prev_scaled && wnd * 101 / 100 > prev_scaled))
 			return;