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 lists1p.gnu.org (lists1p.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 BEADACA5FC4 for ; Fri, 2 Oct 2026 07:13:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xCXRv-0006Pi-Bf; Fri, 02 Oct 2026 03:12:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xCXRn-0006PS-Mx for qemu-devel@nongnu.org; Fri, 02 Oct 2026 03:12:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xCXRh-00008U-Db for qemu-devel@nongnu.org; Fri, 02 Oct 2026 03:12:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1790925159; 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=JXPcxF34iydpxhga/k7M6/PZAuaxm9PIB36XqH/1a+c=; b=NB6APLr3I9dsJjF9s5KScNtkq9vpOPxZ3unwR+SEUw7gL6un6xhoi8zQOzjbMwRFX9H/RW /f9WLAVA9ZCbjxSK8+17cDwgRIoUgCu6mF6ahi4pRk/mnM/qhdb7qwcju8BXVN4kY54Hfr ECMUE7XU6F4BPWvt1SyQSbDIDpoYM7U= Received: from mx-prod-mc-01.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-648-OhPJcY4gPAmeQWSZN2U-9g-1; Fri, 02 Oct 2026 03:12:35 -0400 X-MC-Unique: OhPJcY4gPAmeQWSZN2U-9g-1 X-Mimecast-MFC-AGG-ID: OhPJcY4gPAmeQWSZN2U-9g_1790925154 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7C4F21955EAE for ; Fri, 2 Oct 2026 07:12:34 +0000 (UTC) Received: from redhat.com (headnet05.pony-001.prod.iad2.dc.redhat.com [10.2.32.117]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4D5B019560AB; Fri, 2 Oct 2026 07:12:32 +0000 (UTC) Date: Fri, 2 Oct 2026 08:12:30 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: marcandre.lureau@redhat.com Cc: qemu-devel@nongnu.org, Stefan Hajnoczi Subject: Re: [PATCH 14/20] audio: remove mistaken use of trace_event_get_state() Message-ID: References: <20261001151228.3373747-1-berrange@redhat.com> <20261001151228.3373747-15-berrange@redhat.com> <179088207684.2348671.16379393864005992729.b4-review@b4> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <179088207684.2348671.16379393864005992729.b4-review@b4> User-Agent: Mutt/2.4.2 (2026-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 9 X-Spam_score: 0.9 X-Spam_bar: / X-Spam_report: (0.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.331, 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_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 Thu, Oct 01, 2026 at 11:14:36PM +0400, marcandre.lureau@redhat.com wrote: > > Conditional checks must call trace_event_get_state_dynamic() > > get_state_backends()? Opps, yes. > > which checks the state of all backends, while trace_event_get_state() > > only validates state for backends using QEMU's internal state > > tracking. > > I don't understand, tbh, but the doc & tracing.rst agree so, We have a "uint16_t _TRACE....DSTATE" variable for each probe that tracks whether QEMU has marked it enabled or not. This is used to control the ftrace, syslog, log and simple trace backends, and what the -trace command line arg sets. This is what the trace_event_get_state() macro checks. For the systemtap and ust backends, however, that variable is not used, as they use USDT which are dynamically enabled by the external tracing application. They proide a semaphore which can be checked to see if the USDT has been enabled. The "TRACE...DSTATE()" macro (no leading underscore) expands to code that checks the systemtap/ust USDT semaphores *and* the QEMU "_TRACE...DSTATE" variable. This is what the correct trace_event_get_state_backends() macro checks, and thus what needs to be used to ensure things work with dtrace/ust backends, as well as the QEMU internal backends. > Reviewed-by: Marc-André Lureau With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|