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@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Peter Newman <peternewman@google.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>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Tan Shaopeng <tan.shaopeng@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20231017002308.134480-2-babu.moger@amd.com

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index 4c6421e2aa31cd47fea25dacb2204f5fa6dc19e4..178ab1d8f7475279f105d77e28899a0978e4b4a8 100644 (file)
--- 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 09848ff11f7ba4a669bde2f4fd0557a5b2baeeae..fe239691628ac6fd421d85087c5a9cd3e9f4aa8e 100644 (file)
--- 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);