Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3;
Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C
From:   Babu Moger <babu.moger@amd.com>
To:     <corbet@lwn.net>, <reinette.chatre@intel.com>,
        <tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>
CC:     <fenghua.yu@intel.com>, <dave.hansen@linux.intel.com>,
        <x86@kernel.org>, <hpa@zytor.com>, <paulmck@kernel.org>,
        <akpm@linux-foundation.org>, <quic_neeraju@quicinc.com>,
        <rdunlap@infradead.org>, <damien.lemoal@opensource.wdc.com>,
        <songmuchun@bytedance.com>, <peterz@infradead.org>,
        <jpoimboe@kernel.org>, <pbonzini@redhat.com>, <babu.moger@amd.com>,
        <chang.seok.bae@intel.com>, <pawan.kumar.gupta@linux.intel.com>,
        <jmattson@google.com>, <daniel.sneddon@linux.intel.com>,
        <sandipan.das@amd.com>, <tony.luck@intel.com>,
        <james.morse@arm.com>, <linux-doc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <bagasdotme@gmail.com>,
        <eranian@google.com>, <christophe.leroy@csgroup.eu>,
        <jarkko@kernel.org>, <adrian.hunter@intel.com>,
        <quic_jiles@quicinc.com>, <peternewman@google.com>
Subject: [PATCH v11 01/10] x86/resctrl: Add multiple tasks to the resctrl group at once
Date:   Tue, 3 Oct 2023 18:54:21 -0500
Message-ID: <20231003235430.1231238-2-babu.moger@amd.com>
In-Reply-To: <20231003235430.1231238-1-babu.moger@amd.com>
References: <20231003235430.1231238-1-babu.moger@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8bit
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Oct 2023 23:54:47.6415
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: cf9cbbf1-a000-4710-5823-08dbc46c2024
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000044FC.namprd21.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY5PR12MB6576
X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable
	autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Tue, 03 Oct 2023 16:55:57 -0700 (PDT)

The resctrl task assignment for monitor or control group needs to be
done one at a time. For example:

  $mount -t resctrl resctrl /sys/fs/resctrl/
  $mkdir /sys/fs/resctrl/ctrl_grp1
  $echo 123 > /sys/fs/resctrl/ctrl_grp1/tasks
  $echo 456 > /sys/fs/resctrl/ctrl_grp1/tasks
  $echo 789 > /sys/fs/resctrl/ctrl_grp1/tasks

This is not user-friendly when dealing with hundreds of tasks.

Support multiple task assignment in one command with tasks ids separated
by commas. For example:
  $echo 123,456,789 > /sys/fs/resctrl/ctrl_grp1/tasks

Signed-off-by: Babu Moger <babu.moger@amd.com>
Tested-by: Peter Newman <peternewman@google.com>
Reviewed-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 Documentation/arch/x86/resctrl.rst     |  9 ++++++++-
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 25 ++++++++++++++++++++++---
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index cb05d90111b4..8154e9975d1e 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -299,7 +299,14 @@ All groups contain the following files:
 "tasks":
 	Reading this file shows the list of all tasks that belong to
 	this group. Writing a task id to the file will add a task to the
-	group. If the group is a CTRL_MON group the task is removed from
+	group. Multiple tasks can be added by separating the task ids
+	with commas. Tasks will be assigned sequentially. Multiple
+	failures are not supported. A single failure encountered while
+	attempting to assign a task will cause the operation to abort and
+	already added tasks before the failure will remain in the group.
+	Failures will be logged to /sys/fs/resctrl/info/last_cmd_status.
+
+	If the group is a CTRL_MON group the task is removed from
 	whichever previous CTRL_MON group owned the task and also from
 	any MON group that owned the task. If the group is a MON group,
 	then the task must already belong to the CTRL_MON parent of this
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 725344048f85..f0d163950969 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -696,11 +696,10 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
 				    char *buf, size_t nbytes, loff_t off)
 {
 	struct rdtgroup *rdtgrp;
+	char *pid_str;
 	int ret = 0;
 	pid_t pid;
 
-	if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
-		return -EINVAL;
 	rdtgrp = rdtgroup_kn_lock_live(of->kn);
 	if (!rdtgrp) {
 		rdtgroup_kn_unlock(of->kn);
@@ -715,7 +714,27 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
 		goto unlock;
 	}
 
-	ret = rdtgroup_move_task(pid, rdtgrp, of);
+	while (buf && buf[0] != '\0' && buf[0] != '\n') {
+		pid_str = strim(strsep(&buf, ","));
+
+		if (kstrtoint(pid_str, 0, &pid)) {
+			rdt_last_cmd_printf("Task list parsing error pid %s\n", pid_str);
+			ret = -EINVAL;
+			break;
+		}
+
+		if (pid < 0) {
+			rdt_last_cmd_printf("Invalid pid %d\n", pid);
+			ret = -EINVAL;
+			break;
+		}
+
+		ret = rdtgroup_move_task(pid, rdtgrp, of);
+		if (ret) {
+			rdt_last_cmd_printf("Error while processing task %d\n", pid);
+			break;
+		}
+	}
 
 unlock:
 	rdtgroup_kn_unlock(of->kn);
-- 
2.34.1