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 95615CEACEF for ; Mon, 17 Nov 2025 13:59:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vKzl0-0004Gu-3e; Mon, 17 Nov 2025 08:59:02 -0500 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 1vKzkq-0004G6-26 for qemu-devel@nongnu.org; Mon, 17 Nov 2025 08:58:53 -0500 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 1vKzkn-0007km-FO for qemu-devel@nongnu.org; Mon, 17 Nov 2025 08:58:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763387926; h=from:from: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=QY6EyeHC6xxWSjZ/+6wsu6VjEqvl4sOXMw9JWwZUy2w=; b=HM6p767ifbXe0K+0aIyJtCNg7IX7m0DUGKP2tnCu5GZXRLO33Qv6Ps1kkGAJwsYCd27B1y 1mTneewEfBdcNQDlfN7+Ykio55V5kOkuad0PiOcDWmGManw8Fl2i9uGMQt2eLsyWxWitNt idlKhvwdzulV2E0rjA5Gdu8+KfpYMtc= Received: from mx-prod-mc-03.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-411--FICa-b5N-eHUi5_ZnI5Pg-1; Mon, 17 Nov 2025 08:58:43 -0500 X-MC-Unique: -FICa-b5N-eHUi5_ZnI5Pg-1 X-Mimecast-MFC-AGG-ID: -FICa-b5N-eHUi5_ZnI5Pg_1763387921 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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4549618AB419; Mon, 17 Nov 2025 13:58:41 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.18]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AD33F19560A7; Mon, 17 Nov 2025 13:58:40 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 03A3B21E6A27; Mon, 17 Nov 2025 14:58:38 +0100 (CET) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, Jason Wang , Andrew Melnychenko , Yuri Benditovich Subject: Re: ebpf functions can fail without setting an error In-Reply-To: <87sehfsife.fsf@pond.sub.org> (Markus Armbruster's message of "Mon, 25 Aug 2025 14:19:01 +0200") References: <87ectns27j.fsf@pond.sub.org> <87sehfsife.fsf@pond.sub.org> Date: Mon, 17 Nov 2025 14:58:37 +0100 Message-ID: <871plwpxpu.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Markus Armbruster writes: > Daniel P. Berrang=C3=A9 writes: > >> On Thu, Aug 07, 2025 at 03:14:56PM +0200, Markus Armbruster wrote: >>> Three functions in ebpf_rss.h take an Error ** argument and return bool. >>> Good. >>>=20 >>> They can all fail without setting an error. Not good. >>>=20 >>> The failures without error are: >>>=20 >>> * All three stubs in ebpf_rss-stub.c always. Oversight? >> >> Opps, yes, we really should have added error_setg() calls for diagnosis >> if someone tries to use eBPF when QEMU build has it disabled. Easy enough, but... > Some stubs exist only to mollify the linker. They are not meant to be > called. They should abort(), optionally with lipstick. > > Other stubs are called and should fail nicely. > > Can you tell me offhand which kind these are? If calling these stubs is possible, I'd like to know how I can get them called, so I can test the errors I add. If calling is not possible, I'd rather add abort()s. I tried to figure out whether calling is possible, but it ended in confusion. Can you help? >>> * Non-stub ebpf_rss_load() when ebpf_rss_is_loaded(). Are these >>> reachable? >> >> This scenario should never happen, and we should add a call like >> >> error_setg(errp, "eBPF program is already loaded"); >> >> to report it correctly. > > Is it a programming error when it happens? This question is still open as well.