From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6A3D1C3DA4A for ; Fri, 16 Aug 2024 08:45:19 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sesZo-0008SX-5A; Fri, 16 Aug 2024 04:44:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sesZk-0008Rv-1I for qemu-devel@nongnu.org; Fri, 16 Aug 2024 04:44:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sesZi-0006dw-9p for qemu-devel@nongnu.org; Fri, 16 Aug 2024 04:44:47 -0400 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: References: <20240814224132.897098-1-pierrick.bouvier@linaro.org> <20240814224132.897098-2-pierrick.bouvier@linaro.org> <66f144dd-f098-443b-8a34-d68bbdecc48f@redhat.com> 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 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.131, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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 :|