From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 B110B1DFFC for ; Fri, 16 Aug 2024 08:44:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723797887; cv=none; b=oG/9GsQbTPSMfdRvkxNCGDmRhcDrJg7bd2cW3SspwS/9Q5k07DcHhtkJy2g987eOaJ5nop9vworQ63Bdw3wdGg+rC4/ufav17Afu9bS5N4qSA3+7fOpgt2iFp5o3XSJ96W9Vm6iUsB7+dQPkg7U/RtA/nzm4IYzgr1Qr55Kbxf8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723797887; c=relaxed/simple; bh=3dGK9RVkTMIiKhNkkvEWdQNA4twAu4r5HzjnWuKjYoc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iA0MNtYCZDrWXjbuT+3HcH6jfxUHqguFdUMNiX4Qzu3YPUaoySQYdhQh7bYDT4wf1Rc93+i9WVzViAkjUYN0Yq6O01NfHBgmlhZuDlbucuvVGaFO3oqTV5YBfqdbPM7kumjmgOUdPa8OxZy8sHKYLqQdzydjfk4Nftdg5MvNHyI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=WjgLjJ0O; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WjgLjJ0O" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1723797884; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gA5jdq5dLKzufFOVi0jOEI5ost4zThD+hb6Vt+IMbFc=; b=WjgLjJ0Od9LwPXS9FzeHiRztA7Jy4aS0huOY34nfKvGlCm2vuharORjfvU/wiOZ+V2hO0e 5DYTPJU26y0O0a5RWhCe7gARyQ6nddjRGUcBk5F34aKpjPC36R7BYCvAG2Ws3qCFZFaLFN N6qoT1/fEoJWJuINM5lT+oLUXFVRPes= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-599-Sjs8SNsAMqait3Xiq3HaTA-1; Fri, 16 Aug 2024 04:44:41 -0400 X-MC-Unique: Sjs8SNsAMqait3Xiq3HaTA-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7F0D81955BFC; Fri, 16 Aug 2024 08:44:39 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.143]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 659E81955F23; Fri, 16 Aug 2024 08:44:33 +0000 (UTC) Date: Fri, 16 Aug 2024 09:44:29 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Thomas Huth Cc: Peter Maydell , Pierrick Bouvier , qemu-devel@nongnu.org, Beraldo Leal , David Hildenbrand , Marcelo Tosatti , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Paolo Bonzini , kvm@vger.kernel.org, Wainer dos Santos Moschetta , qemu-s390x@nongnu.org, =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Richard Henderson , Alex =?utf-8?Q?Benn=C3=A9e?= , Ilya Leoshkevich Subject: Re: [PATCH v2 1/4] meson: hide tsan related warnings Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20240814224132.897098-1-pierrick.bouvier@linaro.org> <20240814224132.897098-2-pierrick.bouvier@linaro.org> <66f144dd-f098-443b-8a34-d68bbdecc48f@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <66f144dd-f098-443b-8a34-d68bbdecc48f@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On Fri, Aug 16, 2024 at 07:44:28AM +0200, Thomas Huth wrote: > On 15/08/2024 19.54, Peter Maydell wrote: > > On Thu, 15 Aug 2024 at 12:05, Daniel P. Berrangé wrote: > > > > > > On Thu, Aug 15, 2024 at 11:12:39AM +0100, Peter Maydell wrote: > > > > On Wed, 14 Aug 2024 at 23:42, Pierrick Bouvier > > > > wrote: > > > > > > > > > > When building with gcc-12 -fsanitize=thread, gcc reports some > > > > > constructions not supported with tsan. > > > > > Found on debian stable. > > > > > > > > > > qemu/include/qemu/atomic.h:36:52: error: ‘atomic_thread_fence’ is not supported with ‘-fsanitize=thread’ [-Werror=tsan] > > > > > 36 | #define smp_mb() ({ barrier(); __atomic_thread_fence(__ATOMIC_SEQ_CST); }) > > > > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > > > > > > > Signed-off-by: Pierrick Bouvier > > > > > --- > > > > > meson.build | 10 +++++++++- > > > > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/meson.build b/meson.build > > > > > index 81ecd4bae7c..52e5aa95cc0 100644 > > > > > --- a/meson.build > > > > > +++ b/meson.build > > > > > @@ -499,7 +499,15 @@ if get_option('tsan') > > > > > prefix: '#include ') > > > > > error('Cannot enable TSAN due to missing fiber annotation interface') > > > > > endif > > > > > - qemu_cflags = ['-fsanitize=thread'] + qemu_cflags > > > > > + tsan_warn_suppress = [] > > > > > + # gcc (>=11) will report constructions not supported by tsan: > > > > > + # "error: ‘atomic_thread_fence’ is not supported with ‘-fsanitize=thread’" > > > > > + # https://gcc.gnu.org/gcc-11/changes.html > > > > > + # However, clang does not support this warning and this triggers an error. > > > > > + if cc.has_argument('-Wno-tsan') > > > > > + tsan_warn_suppress = ['-Wno-tsan'] > > > > > + endif > > > > > > > > That last part sounds like a clang bug -- -Wno-foo is supposed > > > > to not be an error on compilers that don't implement -Wfoo for > > > > any value of foo (unless some other warning/error would also > > > > be emitted). > > > > > > -Wno-foo isn't an error, but it is a warning... which we then > > > turn into an error due to -Werror, unless we pass -Wno-unknown-warning-option > > > to clang. > > > > Which is irritating if you want to be able to blanket say > > '-Wno-silly-compiler-warning' and not see any of that > > warning regardless of compiler version. That's why the > > gcc behaviour is the way it is (i.e. -Wno-such-thingy > > is neither a warning nor an error if it would be the only > > warning/error), and if clang doesn't match it that's a shame. > > I thought that Clang would behave the same way as GCC, but apparently it > does not (anymore?): It is nothing new - clang has behaved this way wrt unknown warning flags for as long as I remember. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|