From nobody Sat Apr 4 06:26:44 2026 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3D2EC31D366 for ; Fri, 20 Mar 2026 22:04:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774044247; cv=none; b=lwoCGBPEUeFg1xwDN0JgAW+ViKV3OrkZKgOx5OwMG8I3AS7xyzpIL6bJYWAD+FU7nPLygyv8gKhNzSTVEXbB476HXZNbNqr1rEUdsKxnE2KQ7d22hW0NNjwK2HklEIczdTxv0wy+6+zFg1rUk8OACQ7+6y+/5mLC9c5rEbljIgI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774044247; c=relaxed/simple; bh=uagmdC59hqouoC9nt3mOjxUbMXJKXQbu0do93cnTrSg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SusjV+HPiCmAmNeHawMCufJRh0WHR5siMDs+F+JkxwzqG+2yoURlUNmTZA5/YPrunUAtYo+G34kgilm/JQFtKD/qAufT7rL1ib7zPFy5V73I2PUUTZ6azRRYPNKnQ1eZSZepbFtBSXh09OoKTKyGs5FtbSfK8jjEnKwAl1twb4Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=NOkdTkTd; arc=none smtp.client-ip=198.175.65.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="NOkdTkTd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1774044245; x=1805580245; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=uagmdC59hqouoC9nt3mOjxUbMXJKXQbu0do93cnTrSg=; b=NOkdTkTdyENTKYvGxzxYb3eOkz2/X4oDT6sYYj2tnTDg06ab1dxBzx86 7dtv1VC2qZCAeS6+t4cRLg1fpn9e+nRTuuFu7RQ0ReUPErk5ICkAOUYvV wSHXZ+hL3ujfgd+Sbg27Uv+Z6zyx/LjMAlVyYKnlTfPWQJ0JENtmGbeDN rSq8bL329YVvce+oB6y/+VywaarGE5MoGb5ca9tFbDp5s+o5dHn/yCf4B vIC0e/8rWQ9JQ1ll5emmhmKhyACq2TVHnjbInbb4cPnsBQM3bGsPA8rFJ tTERhW5xmQK2Oi+JUiYdJPldiFtT50AP+YkjqNok1Y717Qt1XsUgLQRrm A==; X-CSE-ConnectionGUID: +/MDKB9jQy6ojaTkLbLT8g== X-CSE-MsgGUID: jNNKfLXVQGWct2u+xfpslg== X-IronPort-AV: E=McAfee;i="6800,10657,11735"; a="97758468" X-IronPort-AV: E=Sophos;i="6.23,132,1770624000"; d="scan'208";a="97758468" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Mar 2026 15:03:58 -0700 X-CSE-ConnectionGUID: cVN8upLqQGmxa+GQjXHNwA== X-CSE-MsgGUID: mbKrV3A7TvKJsSOZ0m/2Tg== X-ExtLoop1: 1 Received: from rchatre-desk1.jf.intel.com ([10.165.154.99]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Mar 2026 15:03:57 -0700 From: Reinette Chatre To: tony.luck@intel.com, james.morse@arm.com, Dave.Martin@arm.com, babu.moger@amd.com, bp@alien8.de, tglx@linutronix.de, dave.hansen@linux.intel.com Cc: x86@kernel.org, hpa@zytor.com, ben.horgan@arm.com, fustini@kernel.org, fenghuay@nvidia.com, peternewman@google.com, linux-kernel@vger.kernel.org, patches@lists.linux.dev, reinette.chatre@intel.com Subject: [PATCH v2 14/14] fs/resctrl: Inform user space when status buffer overflowed Date: Fri, 20 Mar 2026 15:03:24 -0700 Message-ID: <0a2c56ac55725fe3131e214297649b9416671b9e.1774043709.git.reinette.chatre@intel.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" resctrl fs commands are becoming more powerful with, for example, a user able to use syntax like '*' to make broad configuration changes. Such commands that span multiple domains may result in more than one message printed to the last_cmd_status buffer with more planned. Display "[truncated]" to user space when displaying the last_cmd_status buffer to communicate if it overflowed. Upon encountering this user space is expected to combine details about the failure found in info/last_cmd_sta= tus with related resctrl files to learn the accurate system state after the command failure. Signed-off-by: Reinette Chatre Reviewed-by: Ben Horgan --- fs/resctrl/rdtgroup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 0f753a820702..85d3ec36cd95 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -973,10 +973,13 @@ static int rdt_last_cmd_status_show(struct kernfs_ope= n_file *of, =20 mutex_lock(&rdtgroup_mutex); len =3D seq_buf_used(&last_cmd_status); - if (len) + if (len) { seq_printf(seq, "%.*s", len, last_cmd_status_buf); - else + if (seq_buf_has_overflowed(&last_cmd_status)) + seq_puts(seq, "[truncated]\n"); + } else { seq_puts(seq, "ok\n"); + } mutex_unlock(&rdtgroup_mutex); return 0; } --=20 2.50.1