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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758793591; 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=VCiJbepTzAS/un2RtpHR4Hvplf9c95e2auSHQriyqk4=; b=VW3UILIXzmiwAY4zqR6lN1RGNDPo8bBBT9sJ9+eKpZLRWYozYm6N2+Z3uEOzVMA0gLw+b5 ag6uvwFpws2fR0lB8qEW75yYVelWAeMoeSi/oPDKehbOguXQ8WR7rxAAJigTPOkN9sYUFk uHuqY8p+ddQOzCqSGqR5rx7g/Iso70o= X-MC-Unique: DE_8BKf3NRuGZdH2N0NOYg-1 X-Mimecast-MFC-AGG-ID: DE_8BKf3NRuGZdH2N0NOYg_1758793588 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: Hanna Reitz , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Kevin Wolf , qemu-rust@nongnu.org, Richard Henderson , Markus Armbruster , Christian Schoenebeck , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , qemu-block@nongnu.org, Stefan Weil , "Dr. David Alan Gilbert" , Manos Pitsidianakis , Gerd Hoffmann , devel@lists.libvirt.org, Paolo Bonzini Subject: [PATCH v4 17/23] util: fix interleaving of error prefixes Date: Thu, 25 Sep 2025 10:44:35 +0100 Message-ID: <20250925094441.1651372-18-berrange@redhat.com> In-Reply-To: <20250925094441.1651372-1-berrange@redhat.com> References: <20250925094441.1651372-1-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=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.444, 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_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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1758793976475116600 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. Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Philippe Mathieu-Daud=C3=A9 Reviewed-by: Richard Henderson --- util/error-report.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/util/error-report.c b/util/error-report.c index 222c40d0d1..b6aa20dbae 100644 --- a/util/error-report.c +++ b/util/error-report.c @@ -226,6 +226,8 @@ static void vreport(report_type type, const char *fmt, = va_list ap) =20 if (monitor_cur_is_hmp()) { cur =3D monitor_cur(); + } else { + flockfile(stderr); } =20 if (message_with_timestamp && !cur) { @@ -254,6 +256,10 @@ 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) { + funlockfile(stderr); + } } =20 /* --=20 2.50.1