From nobody Tue Mar 24 00:56:56 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1772733063; cv=none; d=zohomail.com; s=zohoarc; b=jKjNiMey922HAH9m4+GoWtTFxofmrvJyrNm/mjjuSNr4g9wTRokKZijvvvQKuM+TjW6TDfyc1gWb927BKPEmAxpoqeczW7+G0CCDGHmfYA6m09TXabKGl5zGqJh1mDhOYRbkS6KKecsw6DbQMf+H9JUJuzE3EwnKaHZ2EK4IZgM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1772733063; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=SJZuudeoh6gQkXCj0qppSeaHkJ9Q/5Q+mEnQLOlYXv0=; b=Ysep/fX2madjyr32FjZueCEn8BNTv38qyOq70IF6EcvwBnOTizpT8s/iaytaRcddoxp/WhRZNZ35u+b4PDxDPreZUngXF5XYJ85QuBRxtD7zBl4kPyz2V0XMwk8dslQkhE616Tnq+XypHp5GZSsFU48vXAtA032PhdZIddT33yw= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1772733063312996.4694055615523; Thu, 5 Mar 2026 09:51:03 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vyCqH-0006jA-Q9; Thu, 05 Mar 2026 12:50:33 -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 1vyCpr-0005yo-Dw for qemu-devel@nongnu.org; Thu, 05 Mar 2026 12:50:07 -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 1vyCpm-0002L9-V2 for qemu-devel@nongnu.org; Thu, 05 Mar 2026 12:50:05 -0500 Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-315-S_j6rhEYNEKbsXkp83cXIA-1; Thu, 05 Mar 2026 12:49:58 -0500 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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A56B8180049D; Thu, 5 Mar 2026 17:49:56 +0000 (UTC) Received: from toolbx.redhat.com (unknown [10.44.34.61]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id BE8B21956095; Thu, 5 Mar 2026 17:49:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772733000; 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=SJZuudeoh6gQkXCj0qppSeaHkJ9Q/5Q+mEnQLOlYXv0=; b=Ll/QjQ49x00duOmTz58eC+yWDM1CuoiF6He4sakEJWOIJJyXwiazDs2SkbBkXk+IcB8yOt bHc15V+qeJCMxCH9Mvlhb8NdVilpOqHEWvyFk3URPrqcuDvwpUwQCq39Shjhx6kUG9q/Xr WQ8H/slp46xHD3MV9K/75R3maYlTuDs= X-MC-Unique: S_j6rhEYNEKbsXkp83cXIA-1 X-Mimecast-MFC-AGG-ID: S_j6rhEYNEKbsXkp83cXIA_1772732996 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Markus Armbruster , Richard Henderson , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , devel@lists.libvirt.org, qemu-rust@nongnu.org, "Dr. David Alan Gilbert" , Gerd Hoffmann , Christian Schoenebeck , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Manos Pitsidianakis , Eduardo Habkost , Pierrick Bouvier , Paolo Bonzini , Stefan Weil Subject: [PULL 23/27] util: fix interleaving of error & trace output Date: Thu, 5 Mar 2026 17:47:39 +0000 Message-ID: <20260305174743.3084606-24-berrange@redhat.com> In-Reply-To: <20260305174743.3084606-1-berrange@redhat.com> References: <20260305174743.3084606-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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: -5 X-Spam_score: -0.6 X-Spam_bar: / X-Spam_report: (-0.6 / 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.892, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.622, 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1772733064085158501 The monitor_cur_hmp() function will acquire/release mutex locks, which will trigger trace probes, which can in turn trigger qemu_log() calls. vreport() calls monitor_cur() multiple times through its execution both directly and indirectly via error_vprintf(). The result is that the prefix information printed by vreport() gets interleaved with qemu_log() output, when run outside the context of an HMP command dispatcher. This can be seen with: $ qemu-system-x86_64 \ -msg timestamp=3Don,guest-name=3Don \ -display none \ -object tls-creds-x509,id=3Df,dir=3Dfish \ -name fish \ -d trace:qemu_mutex* 2025-09-10T16:30:42.514374Z qemu_mutex_unlock released mutex 0x560b0339b= 4c0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:30:42.514400Z qemu_mutex_lock waiting on mutex 0x560b03398= 3e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:30:42.514402Z qemu_mutex_locked taken mutex 0x560b033983e0= (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:30:42.514404Z qemu_mutex_unlock released mutex 0x560b03398= 3e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:30:42.516716Z qemu_mutex_lock waiting on mutex 0x560b03398= 560 (../monitor/monitor.c:91) 2025-09-10T16:30:42.516723Z qemu_mutex_locked taken mutex 0x560b03398560= (../monitor/monitor.c:91) 2025-09-10T16:30:42.516726Z qemu_mutex_unlock released mutex 0x560b03398= 560 (../monitor/monitor.c:96) 2025-09-10T16:30:42.516728Z qemu_mutex_lock waiting on mutex 0x560b03398= 560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842057Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842058Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) 2025-09-10T16:31:04.842055Z 2025-09-10T16:31:04.842060Z qemu_mutex_lock = waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842061Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842062Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) 2025-09-10T16:31:04.842064Z qemu_mutex_lock waiting on mutex 0x564f5e401= 560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842065Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842066Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) fish 2025-09-10T16:31:04.842068Z qemu_mutex_lock waiting on mutex 0x564f= 5e401560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842069Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842070Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) 2025-09-10T16:31:04.842072Z qemu_mutex_lock waiting on mutex 0x564f5e401= 560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842097Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842099Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) qemu-system-x86_64:2025-09-10T16:31:04.842100Z qemu_mutex_lock waiting o= n mutex 0x564f5e401560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842102Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842103Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) 2025-09-10T16:31:04.842105Z qemu_mutex_lock waiting on mutex 0x564f5e40= 1560 (../monitor/monitor.c:91) 2025-09-10T16:31:04.842106Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842107Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) Unable to access credentials fish/ca-cert.pem: No such file or directory= 2025-09-10T16:31:04.842109Z qemu_mutex_lock waiting on mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842110Z qemu_mutex_locked taken mutex 0x564f5e401560= (../monitor/monitor.c:91) 2025-09-10T16:31:04.842111Z qemu_mutex_unlock released mutex 0x564f5e401= 560 (../monitor/monitor.c:96) To avoid this interleaving (as well as reduce the huge number of mutex lock/unlock calls) we need to ensure that monitor_cur_is_hmp() is only called once at the start of vreport(), and if no HMP is present, no further monitor APIs can be called. This implies error_[v]printf() cannot be called from vreport(). Instead we must introduce error_[v]printf_mon() which accept a pre-acquired Monitor object. In some cases, however, fprintf can be called directly as output will never be directed to the monitor. $ qemu-system-x86_64 \ -msg timestamp=3Don,guest-name=3Don \ -display none \ -object tls-creds-x509,id=3Df,dir=3Dfish \ -name fish \ -d trace:qemu_mutex* 2025-09-10T16:31:22.701691Z qemu_mutex_unlock released mutex 0x5626fd3b8= 4c0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:31:22.701728Z qemu_mutex_lock waiting on mutex 0x5626fd3b5= 3e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:31:22.701730Z qemu_mutex_locked taken mutex 0x5626fd3b53e0= (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:31:22.701732Z qemu_mutex_unlock released mutex 0x5626fd3b5= 3e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) 2025-09-10T16:31:22.703989Z qemu_mutex_lock waiting on mutex 0x5626fd3b5= 560 (../monitor/monitor.c:91) 2025-09-10T16:31:22.703996Z qemu_mutex_locked taken mutex 0x5626fd3b5560= (../monitor/monitor.c:91) 2025-09-10T16:31:22.703999Z qemu_mutex_unlock released mutex 0x5626fd3b5= 560 (../monitor/monitor.c:96) 2025-09-10T16:31:22.704000Z fish qemu-system-x86_64: Unable to access cr= edentials fish/ca-cert.pem: No such file or directory Reviewed-by: Richard Henderson Signed-off-by: Daniel P. Berrang=C3=A9 --- util/error-report.c | 63 ++++++++++++++++++++++++++++++--------------- 1 file changed, 42 insertions(+), 21 deletions(-) diff --git a/util/error-report.c b/util/error-report.c index c7f70bd95b..f666ca4149 100644 --- a/util/error-report.c +++ b/util/error-report.c @@ -32,9 +32,9 @@ const char *error_guest_name; /* * Print to the current human monitor if we have one, else to stderr. */ -int error_vprintf(const char *fmt, va_list ap) +static int G_GNUC_PRINTF(2, 0) +error_vprintf_mon(Monitor *cur_mon, const char *fmt, va_list ap) { - Monitor *cur_mon =3D monitor_cur(); /* * This will return -1 if 'cur_mon' is NULL, or is QMP. * IOW this will only print if in HMP, otherwise we @@ -47,13 +47,33 @@ int error_vprintf(const char *fmt, va_list ap) return ret; } =20 +/* + * Print to the current human monitor if we have one, else to stderr. + */ +static int G_GNUC_PRINTF(2, 3) +error_printf_mon(Monitor *cur_mon, const char *fmt, ...) +{ + va_list ap; + int ret; + + va_start(ap, fmt); + ret =3D error_vprintf_mon(cur_mon, fmt, ap); + va_end(ap); + return ret; +} + +int error_vprintf(const char *fmt, va_list ap) +{ + return error_vprintf_mon(monitor_cur(), fmt, ap); +} + int error_printf(const char *fmt, ...) { va_list ap; int ret; =20 va_start(ap, fmt); - ret =3D error_vprintf(fmt, ap); + ret =3D error_vprintf_mon(monitor_cur(), fmt, ap); va_end(ap); return ret; } @@ -156,34 +176,34 @@ void loc_set_file(const char *fname, int lno) /* * Print current location to current monitor if we have one, else to stder= r. */ -static void print_loc(void) +static void print_loc(Monitor *cur) { const char *sep =3D ""; int i; const char *const *argp; =20 - if (!monitor_cur() && g_get_prgname()) { - error_printf("%s:", g_get_prgname()); + if (!cur && g_get_prgname()) { + fprintf(stderr, "%s:", g_get_prgname()); sep =3D " "; } switch (cur_loc->kind) { case LOC_CMDLINE: argp =3D cur_loc->ptr; for (i =3D 0; i < cur_loc->num; i++) { - error_printf("%s%s", sep, argp[i]); + error_printf_mon(cur, "%s%s", sep, argp[i]); sep =3D " "; } - error_printf(": "); + error_printf_mon(cur, ": "); break; case LOC_FILE: - error_printf("%s:", (const char *)cur_loc->ptr); + error_printf_mon(cur, "%s:", (const char *)cur_loc->ptr); if (cur_loc->num) { - error_printf("%d:", cur_loc->num); + error_printf_mon(cur, "%d:", cur_loc->num); } - error_printf(" "); + error_printf_mon(cur, " "); break; default: - error_printf("%s", sep); + error_printf_mon(cur, "%s", sep); } } =20 @@ -203,34 +223,35 @@ char *real_time_iso8601(void) G_GNUC_PRINTF(2, 0) static void vreport(report_type type, const char *fmt, va_list ap) { + Monitor *cur =3D monitor_cur(); gchar *timestr; =20 - if (message_with_timestamp && !monitor_cur()) { + if (message_with_timestamp && !cur) { timestr =3D real_time_iso8601(); - error_printf("%s ", timestr); + fprintf(stderr, "%s ", timestr); g_free(timestr); } =20 /* Only prepend guest name if -msg guest-name and -name guest=3D... ar= e set */ - if (error_with_guestname && error_guest_name && !monitor_cur()) { - error_printf("%s ", error_guest_name); + if (error_with_guestname && error_guest_name && !cur) { + fprintf(stderr, "%s ", error_guest_name); } =20 - print_loc(); + print_loc(cur); =20 switch (type) { case REPORT_TYPE_ERROR: break; case REPORT_TYPE_WARNING: - error_printf("warning: "); + error_printf_mon(cur, "warning: "); break; case REPORT_TYPE_INFO: - error_printf("info: "); + error_printf_mon(cur, "info: "); break; } =20 - error_vprintf(fmt, ap); - error_printf("\n"); + error_vprintf_mon(cur, fmt, ap); + error_printf_mon(cur, "\n"); } =20 /* --=20 2.53.0