linux-kernel - [tip: x86/cache] x86/resctrl: Add multiple tasks to the resctrl group at once

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Message-ID: <169754508299.3135.1526802957654004468.tip-bot2@tip-bot2>
Date:   Tue, 17 Oct 2023 12:18:02 -0000
From:   "tip-bot2 for Babu Moger" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Babu Moger <babu.moger@....com>,
        "Borislav Petkov (AMD)" <bp@...en8.de>,
        Peter Newman <peternewman@...gle.com>,
        Tan Shaopeng <tan.shaopeng@...fujitsu.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        ilpo.jarvinen@...ux.intel.com, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/cache] x86/resctrl: Add multiple tasks to the resctrl group at once

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     fe2a20ea0b0953189e57740debc7dcc789d1ea55
Gitweb:        https://git.kernel.org/tip/fe2a20ea0b0953189e57740debc7dcc789d1ea55
Author:        Babu Moger <babu.moger@....com>
AuthorDate:    Mon, 16 Oct 2023 19:23:00 -05:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Tue, 17 Oct 2023 11:27:50 +02:00

x86/resctrl: Add multiple tasks to the resctrl group at once

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@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Peter Newman <peternewman@...gle.com>
Reviewed-by: Tan Shaopeng <tan.shaopeng@...fujitsu.com>
Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Tested-by: Peter Newman <peternewman@...gle.com>
Tested-by: Tan Shaopeng <tan.shaopeng@...fujitsu.com>
Link: https://lore.kernel.org/r/20231017002308.134480-2-babu.moger@amd.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 4c6421e..178ab1d 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -306,7 +306,14 @@ 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 09848ff..fe23969 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);