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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>
hifive-unleashed-5.1
Fenghua Yu 2016-10-28 15:04:46 -07:00 committed by Thomas Gleixner
parent 12e0110c11
commit e02737d5b8
2 changed files with 183 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

180
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
View File

@ -28,6 +28,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/task_work.h>
#include <uapi/linux/magic.h>
@ -267,6 +268,162 @@ unlock:
return ret ?: nbytes;
}
struct task_move_callback {
struct callback_head work;
struct rdtgroup *rdtgrp;
};
static void move_myself(struct callback_head *head)
{
struct task_move_callback *callback;
struct rdtgroup *rdtgrp;
callback = container_of(head, struct task_move_callback, work);
rdtgrp = callback->rdtgrp;
/*
* If resource group was deleted before this task work callback
* was invoked, then assign the task to root group and free the
* resource group.
*/
if (atomic_dec_and_test(&rdtgrp->waitcount) &&
(rdtgrp->flags & RDT_DELETED)) {
current->closid = 0;
kfree(rdtgrp);
}
kfree(callback);
}
static int __rdtgroup_move_task(struct task_struct *tsk,
struct rdtgroup *rdtgrp)
{
struct task_move_callback *callback;
int ret;
callback = kzalloc(sizeof(*callback), GFP_KERNEL);
if (!callback)
return -ENOMEM;
callback->work.func = move_myself;
callback->rdtgrp = rdtgrp;
/*
* Take a refcount, so rdtgrp cannot be freed before the
* callback has been invoked.
*/
atomic_inc(&rdtgrp->waitcount);
ret = task_work_add(tsk, &callback->work, true);
if (ret) {
/*
* Task is exiting. Drop the refcount and free the callback.
* No need to check the refcount as the group cannot be
* deleted before the write function unlocks rdtgroup_mutex.
*/
atomic_dec(&rdtgrp->waitcount);
kfree(callback);
} else {
tsk->closid = rdtgrp->closid;
}
return ret;
}
static int rdtgroup_task_write_permission(struct task_struct *task,
struct kernfs_open_file *of)
{
const struct cred *tcred = get_task_cred(task);
const struct cred *cred = current_cred();
int ret = 0;
/*
* Even if we're attaching all tasks in the thread group, we only
* need to check permissions on one of them.
*/
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
!uid_eq(cred->euid, tcred->uid) &&
!uid_eq(cred->euid, tcred->suid))
ret = -EPERM;
put_cred(tcred);
return ret;
}
static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
struct kernfs_open_file *of)
{
struct task_struct *tsk;
int ret;
rcu_read_lock();
if (pid) {
tsk = find_task_by_vpid(pid);
if (!tsk) {
rcu_read_unlock();
return -ESRCH;
}
} else {
tsk = current;
}
get_task_struct(tsk);
rcu_read_unlock();
ret = rdtgroup_task_write_permission(tsk, of);
if (!ret)
ret = __rdtgroup_move_task(tsk, rdtgrp);
put_task_struct(tsk);
return ret;
}
static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct rdtgroup *rdtgrp;
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)
ret = rdtgroup_move_task(pid, rdtgrp, of);
else
ret = -ENOENT;
rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
{
struct task_struct *p, *t;
rcu_read_lock();
for_each_process_thread(p, t) {
if (t->closid == r->closid)
seq_printf(s, "%d\n", t->pid);
}
rcu_read_unlock();
}
static int rdtgroup_tasks_show(struct kernfs_open_file *of,
struct seq_file *s, void *v)
{
struct rdtgroup *rdtgrp;
int ret = 0;
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (rdtgrp)
show_rdt_tasks(rdtgrp, s);
else
ret = -ENOENT;
rdtgroup_kn_unlock(of->kn);
return ret;
}
/* Files in each rdtgroup */
static struct rftype rdtgroup_base_files[] = {
{
@ -276,6 +433,13 @@ static struct rftype rdtgroup_base_files[] = {
.write = rdtgroup_cpus_write,
.seq_show = rdtgroup_cpus_show,
},
{
.name = "tasks",
.mode = 0644,
.kf_ops = &rdtgroup_kf_single_ops,
.write = rdtgroup_tasks_write,
.seq_show = rdtgroup_tasks_show,
},
};
static int rdt_num_closids_show(struct kernfs_open_file *of,
@ -592,6 +756,13 @@ static void rdt_reset_pqr_assoc_closid(void *v)
static void rmdir_all_sub(void)
{
struct rdtgroup *rdtgrp, *tmp;
struct task_struct *p, *t;
/* move all tasks to default resource group */
read_lock(&tasklist_lock);
for_each_process_thread(p, t)
t->closid = 0;
read_unlock(&tasklist_lock);
get_cpu();
/* Reset PQR_ASSOC MSR on this cpu. */
@ -712,6 +883,7 @@ out_unlock:
static int rdtgroup_rmdir(struct kernfs_node *kn)
{
struct task_struct *p, *t;
struct rdtgroup *rdtgrp;
int cpu, ret = 0;
@ -721,6 +893,14 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
return -ENOENT;
}
/* Give any tasks back to the default group */
read_lock(&tasklist_lock);
for_each_process_thread(p, t) {
if (t->closid == rdtgrp->closid)
t->closid = 0;
}
read_unlock(&tasklist_lock);
/* Give any CPUs back to the default group */
cpumask_or(&rdtgroup_default.cpu_mask,
&rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);

3
include/linux/sched.h
View File

@ -1791,6 +1791,9 @@ struct task_struct {
/* cg_list protected by css_set_lock and tsk->alloc_lock */
struct list_head cg_list;
#endif
#ifdef CONFIG_INTEL_RDT_A
int closid;
#endif
#ifdef CONFIG_FUTEX
struct robust_list_head __user *robust_list;
#ifdef CONFIG_COMPAT