From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 33860BA3F; Wed, 3 Sep 2025 22:15:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756937756; cv=none; b=Dk87y3D4yH9meF9m/QMWPNh61gb+1uA8HiPP15tc7JlrD2ti1OKWXmXmEQ7BJClpMoCXKcYY8Q4qI4T1LB0wX4Ossm86tymRD6cHIJUNsRffad53ZScgLeqeIJiBmBckhyiaBFk7VFEYwryKqDqmhco5Jl1j8iDVfIESBR3W4As= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756937756; c=relaxed/simple; bh=FjCxsXTO2y1dcCLjYVy+WtH9zNK8OPmf+oe47T3YX4Q=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=cDdXX4+2eMRq88N5421E1UUjamkTOK0M2GJe7FB3I8aozxX/7dhMzw0VaHWelUPYh8aFUZmIVDy3IJRv974ZQenW1LrM2uM2YNGcDiMIaic3mgIG9bpNV+jCTC1sJn9tATPlxdH6Tk4lTtbGsF3H32JPN55unJvYPkpeerHJYeE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f29Eyqlq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f29Eyqlq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 771E0C4CEE7; Wed, 3 Sep 2025 22:15:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756937755; bh=FjCxsXTO2y1dcCLjYVy+WtH9zNK8OPmf+oe47T3YX4Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=f29EyqlqLRMXeIWuZJitiNpeH+sT89UwgxyPvp2eO7nIggZXyOzUvRmFT664V3Y+5 hT4Qe6gNYItnV3OsnFVhk+sKwkV9Xt30TkTk9J7wLXh+dK3V6nvNbzRe6UShvacKq7 1Vdn49ucvrmSBc4RdoT4+sK6MVIQQAsp0ShyTrzXFuPdQ9ZEQhvi4qtX9taKHq0MAG 6Hra8sQuQJGCtKJZRD8Gegr0oR3Bcau9cs9TR49LkWir54tKASsb22+aLo8/3BU/DF v4zuvzEQ+P7fxHWIAsJZFBrurUDtcdGc7Ts/9tVh7PZIdd+sxhkcDZ+Lf17KY69B22 FaLE2GI9aB4nA== Date: Wed, 3 Sep 2025 15:15:54 -0700 From: Jakub Kicinski To: Florian Westphal Cc: , Paolo Abeni , "David S. Miller" , Eric Dumazet , , pablo@netfilter.org Subject: Re: [PATCH net 1/2] selftests: netfilter: fix udpclash tool hang Message-ID: <20250903151554.5c72661e@kernel.org> In-Reply-To: <20250902185855.25919-2-fw@strlen.de> References: <20250902185855.25919-1-fw@strlen.de> <20250902185855.25919-2-fw@strlen.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 2 Sep 2025 20:58:54 +0200 Florian Westphal wrote: > Yi Chen reports that 'udpclash' loops forever depending on compiler > (and optimization level used); while (x =3D=3D 1) gets optimized into > for (;;). Switch to stdatomic to prevent this. gcc version 15.1.1 (F42) w/ whatever flags kselftests use appear to be unaware of this macro: udpclash.c:33:26: error: implicit declaration of function =E2=80=98ATOMIC_V= AR_INIT=E2=80=99; did you mean =E2=80=98ATOMIC_FLAG_INIT=E2=80=99? [-Wimpli= cit-function-declaration] 33 | static atomic_int wait =3D ATOMIC_VAR_INIT(1); | ^~~~~~~~~~~~~~~ | ATOMIC_FLAG_INIT udpclash.c:33:26: error: initializer element is not constant Could you perhaps use volatile instead? > +#include > #include > #include > #include > @@ -29,7 +30,7 @@ struct thread_args { > int sockfd; > }; > =20 > -static int wait =3D 1; > +static atomic_int wait =3D ATOMIC_VAR_INIT(1); > =20 > static void *thread_main(void *varg) > {