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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770823638; 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=skHP4pTjXRgohkxWEwFUDHKfYizotJdlGmYSDlwigUI=; b=KLyVjVCuufTs2VTjqnbldpevtfoRFMbb9RKBCWZ/44gLPK8sL5qDGpc0z33MDMBTsrMRB7 CpDNjQ2ZLBakEc04a2+5w2yCb872mc8txX/Kc2YBTrsT3XQFDEGD/4HQRd3I9kCkal4ulk TjudKXYh8pi1meGW5AO5+ikqyoDau7I= X-MC-Unique: BRL-aCMlN9G42B_0iH0fgw-1 X-Mimecast-MFC-AGG-ID: BRL-aCMlN9G42B_0iH0fgw_1770823635 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Manos Pitsidianakis , Stefan Weil , "Dr. David Alan Gilbert" , Pierrick Bouvier , devel@lists.libvirt.org, =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Hanna Reitz , Kevin Wolf , qemu-block@nongnu.org, qemu-rust@nongnu.org, Paolo Bonzini , Markus Armbruster , Gerd Hoffmann , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Christian Schoenebeck , Richard Henderson Subject: [PATCH v6 21/27] util: fix interleaving of error prefixes Date: Wed, 11 Feb 2026 15:25:02 +0000 Message-ID: <20260211152508.732487-22-berrange@redhat.com> In-Reply-To: <20260211152508.732487-1-berrange@redhat.com> References: <20260211152508.732487-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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=170.10.133.124; envelope-from=berrange@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_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable 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: 1770823859931154100 The vreport() function will optionally emit an prefix for error messages which is output to stderr incrementally. In the event that two vreport() calls execute concurrently, there is a risk that the prefix output will interleave. To address this it is required to take a lock on 'stderr' when outputting errors. Reported-by: Markus Armbruster Reviewed-by: Philippe Mathieu-Daud=C3=A9 Reviewed-by: Richard Henderson Reviewed-by: Markus Armbruster Signed-off-by: Daniel P. Berrang=C3=A9 --- util/error-report.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/util/error-report.c b/util/error-report.c index 052f0f68b8..516d323ffe 100644 --- a/util/error-report.c +++ b/util/error-report.c @@ -234,6 +234,9 @@ static void vreport(report_type type, const char *fmt, = va_list ap) if (monitor_cur_is_qmp()) { cur =3D NULL; } + if (!cur) { + qemu_flockfile(stderr); + } =20 if (message_with_timestamp && !cur) { timestr =3D real_time_iso8601(); @@ -261,6 +264,10 @@ static void vreport(report_type type, const char *fmt,= va_list ap) =20 error_vprintf_mon(cur, fmt, ap); error_printf_mon(cur, "\n"); + + if (!cur) { + qemu_funlockfile(stderr); + } } =20 /* --=20 2.53.0