x86/intel_rdt: Add tasks files
The root directory all subdirectories are automatically populated with a read/write (mode 0644) file named "tasks". When read it will show all the task IDs assigned to the resource group. Tasks can be added (one at a time) to a group by writing the task ID to the file. E.g. Membership in a resource group is indicated by a new field in the task_struct "int closid" which holds the CLOSID for each task. The default resource group uses CLOSID=0 which means that all existing tasks when the resctrl file system is mounted belong to the default group. If a group is removed, tasks which are members of that group are moved to the default group. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com> Cc: "Tony Luck" <tony.luck@intel.com> Cc: "Shaohua Li" <shli@fb.com> Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com> Cc: "Peter Zijlstra" <peterz@infradead.org> Cc: "Stephane Eranian" <eranian@google.com> Cc: "Dave Hansen" <dave.hansen@intel.com> Cc: "David Carrillo-Cisneros" <davidcc@google.com> Cc: "Nilay Vaish" <nilayvaish@gmail.com> Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com> Cc: "Ingo Molnar" <mingo@elte.hu> Cc: "Borislav Petkov" <bp@suse.de> Cc: "H. Peter Anvin" <h.peter.anvin@intel.com> Link: http://lkml.kernel.org/r/1477692289-37412-8-git-send-email-fenghua.yu@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Fenghua Yu
Thomas Gleixner
Родитель
12e0110c11
Коммит
e02737d5b8
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@ -28,6 +28,7 @@
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/cpu.h>
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#include <linux/task_work.h>
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#include <uapi/linux/magic.h>
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@ -267,6 +268,162 @@ unlock:
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return ret ?: nbytes;
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}
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struct task_move_callback {
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struct callback_head work;
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struct rdtgroup *rdtgrp;
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};
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static void move_myself(struct callback_head *head)
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{
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struct task_move_callback *callback;
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struct rdtgroup *rdtgrp;
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callback = container_of(head, struct task_move_callback, work);
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rdtgrp = callback->rdtgrp;
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/*
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* If resource group was deleted before this task work callback
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* was invoked, then assign the task to root group and free the
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* resource group.
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*/
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if (atomic_dec_and_test(&rdtgrp->waitcount) &&
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(rdtgrp->flags & RDT_DELETED)) {
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current->closid = 0;
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kfree(rdtgrp);
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}
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kfree(callback);
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}
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static int __rdtgroup_move_task(struct task_struct *tsk,
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struct rdtgroup *rdtgrp)
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{
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struct task_move_callback *callback;
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int ret;
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callback = kzalloc(sizeof(*callback), GFP_KERNEL);
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if (!callback)
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return -ENOMEM;
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callback->work.func = move_myself;
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callback->rdtgrp = rdtgrp;
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/*
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* Take a refcount, so rdtgrp cannot be freed before the
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* callback has been invoked.
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*/
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atomic_inc(&rdtgrp->waitcount);
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ret = task_work_add(tsk, &callback->work, true);
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if (ret) {
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/*
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* Task is exiting. Drop the refcount and free the callback.
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* No need to check the refcount as the group cannot be
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* deleted before the write function unlocks rdtgroup_mutex.
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*/
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atomic_dec(&rdtgrp->waitcount);
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kfree(callback);
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} else {
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tsk->closid = rdtgrp->closid;
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}
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return ret;
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}
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static int rdtgroup_task_write_permission(struct task_struct *task,
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struct kernfs_open_file *of)
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{
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const struct cred *tcred = get_task_cred(task);
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const struct cred *cred = current_cred();
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int ret = 0;
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/*
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* Even if we're attaching all tasks in the thread group, we only
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* need to check permissions on one of them.
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*/
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if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
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!uid_eq(cred->euid, tcred->uid) &&
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!uid_eq(cred->euid, tcred->suid))
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ret = -EPERM;
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put_cred(tcred);
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return ret;
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}
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static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
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struct kernfs_open_file *of)
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{
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struct task_struct *tsk;
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int ret;
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rcu_read_lock();
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if (pid) {
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tsk = find_task_by_vpid(pid);
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if (!tsk) {
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rcu_read_unlock();
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return -ESRCH;
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}
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} else {
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tsk = current;
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}
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get_task_struct(tsk);
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rcu_read_unlock();
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ret = rdtgroup_task_write_permission(tsk, of);
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if (!ret)
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ret = __rdtgroup_move_task(tsk, rdtgrp);
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put_task_struct(tsk);
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return ret;
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}
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static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
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char *buf, size_t nbytes, loff_t off)
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{
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struct rdtgroup *rdtgrp;
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int ret = 0;
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pid_t pid;
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if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
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return -EINVAL;
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rdtgrp = rdtgroup_kn_lock_live(of->kn);
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if (rdtgrp)
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ret = rdtgroup_move_task(pid, rdtgrp, of);
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else
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ret = -ENOENT;
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rdtgroup_kn_unlock(of->kn);
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return ret ?: nbytes;
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}
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static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
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{
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struct task_struct *p, *t;
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rcu_read_lock();
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for_each_process_thread(p, t) {
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if (t->closid == r->closid)
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seq_printf(s, "%d\n", t->pid);
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}
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rcu_read_unlock();
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}
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static int rdtgroup_tasks_show(struct kernfs_open_file *of,
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struct seq_file *s, void *v)
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{
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struct rdtgroup *rdtgrp;
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int ret = 0;
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rdtgrp = rdtgroup_kn_lock_live(of->kn);
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if (rdtgrp)
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show_rdt_tasks(rdtgrp, s);
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else
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ret = -ENOENT;
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rdtgroup_kn_unlock(of->kn);
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return ret;
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}
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/* Files in each rdtgroup */
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static struct rftype rdtgroup_base_files[] = {
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{
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@ -276,6 +433,13 @@ static struct rftype rdtgroup_base_files[] = {
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.write = rdtgroup_cpus_write,
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.seq_show = rdtgroup_cpus_show,
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},
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{
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.name = "tasks",
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.mode = 0644,
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.kf_ops = &rdtgroup_kf_single_ops,
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.write = rdtgroup_tasks_write,
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.seq_show = rdtgroup_tasks_show,
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},
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};
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static int rdt_num_closids_show(struct kernfs_open_file *of,
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@ -592,6 +756,13 @@ static void rdt_reset_pqr_assoc_closid(void *v)
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static void rmdir_all_sub(void)
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{
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struct rdtgroup *rdtgrp, *tmp;
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struct task_struct *p, *t;
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/* move all tasks to default resource group */
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read_lock(&tasklist_lock);
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for_each_process_thread(p, t)
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t->closid = 0;
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read_unlock(&tasklist_lock);
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get_cpu();
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/* Reset PQR_ASSOC MSR on this cpu. */
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@ -712,6 +883,7 @@ out_unlock:
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static int rdtgroup_rmdir(struct kernfs_node *kn)
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{
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struct task_struct *p, *t;
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struct rdtgroup *rdtgrp;
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int cpu, ret = 0;
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@ -721,6 +893,14 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
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return -ENOENT;
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}
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/* Give any tasks back to the default group */
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read_lock(&tasklist_lock);
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for_each_process_thread(p, t) {
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if (t->closid == rdtgrp->closid)
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t->closid = 0;
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}
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read_unlock(&tasklist_lock);
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/* Give any CPUs back to the default group */
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cpumask_or(&rdtgroup_default.cpu_mask,
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&rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
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@ -1791,6 +1791,9 @@ struct task_struct {
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/* cg_list protected by css_set_lock and tsk->alloc_lock */
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struct list_head cg_list;
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#endif
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#ifdef CONFIG_INTEL_RDT_A
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int closid;
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#endif
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#ifdef CONFIG_FUTEX
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struct robust_list_head __user *robust_list;
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#ifdef CONFIG_COMPAT
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