From nobody Tue Oct 28 21:06:30 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1513609242407107.03618655642947; Mon, 18 Dec 2017 07:00:42 -0800 (PST) Received: from localhost ([::1]:42529 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQwuB-0003Uw-Rn for importer@patchew.org; Mon, 18 Dec 2017 10:00:35 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51512) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQwiM-0000SO-4u for qemu-devel@nongnu.org; Mon, 18 Dec 2017 09:48:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eQwiL-00080t-9T for qemu-devel@nongnu.org; Mon, 18 Dec 2017 09:48:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:26831) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eQwiL-0007zu-32 for qemu-devel@nongnu.org; Mon, 18 Dec 2017 09:48:21 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 247498210C; Mon, 18 Dec 2017 14:48:20 +0000 (UTC) Received: from localhost (ovpn-116-227.ams2.redhat.com [10.36.116.227]) by smtp.corp.redhat.com (Postfix) with ESMTP id CCC747F5C8; Mon, 18 Dec 2017 14:48:16 +0000 (UTC) From: Stefan Hajnoczi To: Date: Mon, 18 Dec 2017 14:47:59 +0000 Message-Id: <20171218144800.27337-4-stefanha@redhat.com> In-Reply-To: <20171218144800.27337-1-stefanha@redhat.com> References: <20171218144800.27337-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 18 Dec 2017 14:48:20 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 3/4] trace: Try using tracefs first X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Namhyung Kim , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Namhyung Kim Recent Linux kernel provides separate tracefs which doesn't need to be mounted on the debugfs. Although most systems mount it at the traditional place on the debugfs, it'd be safer to check tracefs first. Signed-off-by: Namhyung Kim Signed-off-by: Stefan Hajnoczi --- trace/ftrace.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/trace/ftrace.c b/trace/ftrace.c index 213cb2205f..61692a8682 100644 --- a/trace/ftrace.c +++ b/trace/ftrace.c @@ -42,12 +42,18 @@ bool ftrace_init(void) { char mount_point[PATH_MAX]; char path[PATH_MAX]; - int debugfs_found; + int tracefs_found; int trace_fd =3D -1; + const char *subdir =3D ""; =20 - debugfs_found =3D find_mount(mount_point, "debugfs"); - if (debugfs_found) { - snprintf(path, PATH_MAX, "%s/tracing/tracing_on", mount_point); + tracefs_found =3D find_mount(mount_point, "tracefs"); + if (!tracefs_found) { + tracefs_found =3D find_mount(mount_point, "debugfs"); + subdir =3D "/tracing"; + } + + if (tracefs_found) { + snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir); trace_fd =3D open(path, O_WRONLY); if (trace_fd < 0) { if (errno =3D=3D EACCES) { @@ -66,14 +72,14 @@ bool ftrace_init(void) } close(trace_fd); } - snprintf(path, PATH_MAX, "%s/tracing/trace_marker", mount_point); + snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir); trace_marker_fd =3D open(path, O_WRONLY); if (trace_marker_fd < 0) { perror("Could not open ftrace 'trace_marker' file"); return false; } } else { - fprintf(stderr, "debugfs is not mounted\n"); + fprintf(stderr, "tracefs is not mounted\n"); return false; } =20 --=20 2.14.3