1 files changed, 275 insertions, 0 deletions

diff --git a/kernel/sched_autogroup.c b/kernel/sched_autogroup.c
new file mode 100644
index 00000000000..429242f3c48
--- /dev/null
+++ b/kernel/sched_autogroup.c
@@ -0,0 +1,275 @@
+#ifdef CONFIG_SCHED_AUTOGROUP
+
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/kallsyms.h>
+#include <linux/utsname.h>
+
+unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
+static struct autogroup autogroup_default;
+static atomic_t autogroup_seq_nr;
+
+static void __init autogroup_init(struct task_struct *init_task)
+{
+        autogroup_default.tg = &root_task_group;
+        kref_init(&autogroup_default.kref);
+        init_rwsem(&autogroup_default.lock);
+        init_task->signal->autogroup = &autogroup_default;
+}
+
+static inline void autogroup_free(struct task_group *tg)
+{
+        kfree(tg->autogroup);
+}
+
+static inline void autogroup_destroy(struct kref *kref)
+{
+        struct autogroup *ag = container_of(kref, struct autogroup, kref);
+
+#ifdef CONFIG_RT_GROUP_SCHED
+        /* We've redirected RT tasks to the root task group... */
+        ag->tg->rt_se = NULL;
+        ag->tg->rt_rq = NULL;
+#endif
+        sched_destroy_group(ag->tg);
+}
+
+static inline void autogroup_kref_put(struct autogroup *ag)
+{
+        kref_put(&ag->kref, autogroup_destroy);
+}
+
+static inline struct autogroup *autogroup_kref_get(struct autogroup *ag)
+{
+        kref_get(&ag->kref);
+        return ag;
+}
+
+static inline struct autogroup *autogroup_task_get(struct task_struct *p)
+{
+        struct autogroup *ag;
+        unsigned long flags;
+
+        if (!lock_task_sighand(p, &flags))
+                return autogroup_kref_get(&autogroup_default);
+
+        ag = autogroup_kref_get(p->signal->autogroup);
+        unlock_task_sighand(p, &flags);
+
+        return ag;
+}
+
+#ifdef CONFIG_RT_GROUP_SCHED
+static void free_rt_sched_group(struct task_group *tg);
+#endif
+
+static inline struct autogroup *autogroup_create(void)
+{
+        struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
+        struct task_group *tg;
+
+        if (!ag)
+                goto out_fail;
+
+        tg = sched_create_group(&root_task_group);
+
+        if (IS_ERR(tg))
+                goto out_free;
+
+        kref_init(&ag->kref);
+        init_rwsem(&ag->lock);
+        ag->id = atomic_inc_return(&autogroup_seq_nr);
+        ag->tg = tg;
+#ifdef CONFIG_RT_GROUP_SCHED
+        /*
+         * Autogroup RT tasks are redirected to the root task group
+         * so we don't have to move tasks around upon policy change,
+         * or flail around trying to allocate bandwidth on the fly.
+         * A bandwidth exception in __sched_setscheduler() allows
+         * the policy change to proceed.  Thereafter, task_group()
+         * returns &root_task_group, so zero bandwidth is required.
+         */
+        free_rt_sched_group(tg);
+        tg->rt_se = root_task_group.rt_se;
+        tg->rt_rq = root_task_group.rt_rq;
+#endif
+        tg->autogroup = ag;
+
+        return ag;
+
+out_free:
+        kfree(ag);
+out_fail:
+        if (printk_ratelimit()) {
+                printk(KERN_WARNING "autogroup_create: %s failure.\n",
+                        ag ? "sched_create_group()" : "kmalloc()");
+        }
+
+        return autogroup_kref_get(&autogroup_default);
+}
+
+static inline bool
+task_wants_autogroup(struct task_struct *p, struct task_group *tg)
+{
+        if (tg != &root_task_group)
+                return false;
+
+        if (p->sched_class != &fair_sched_class)
+                return false;
+
+        /*
+         * We can only assume the task group can't go away on us if
+         * autogroup_move_group() can see us on ->thread_group list.
+         */
+        if (p->flags & PF_EXITING)
+                return false;
+
+        return true;
+}
+
+static inline bool task_group_is_autogroup(struct task_group *tg)
+{
+        return !!tg->autogroup;
+}
+
+static inline struct task_group *
+autogroup_task_group(struct task_struct *p, struct task_group *tg)
+{
+        int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
+
+        if (enabled && task_wants_autogroup(p, tg))
+                return p->signal->autogroup->tg;
+
+        return tg;
+}
+
+static void
+autogroup_move_group(struct task_struct *p, struct autogroup *ag)
+{
+        struct autogroup *prev;
+        struct task_struct *t;
+        unsigned long flags;
+
+        BUG_ON(!lock_task_sighand(p, &flags));
+
+        prev = p->signal->autogroup;
+        if (prev == ag) {
+                unlock_task_sighand(p, &flags);
+                return;
+        }
+
+        p->signal->autogroup = autogroup_kref_get(ag);
+
+        if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled))
+                goto out;
+
+        t = p;
+        do {
+                sched_move_task(t);
+        } while_each_thread(p, t);
+
+out:
+        unlock_task_sighand(p, &flags);
+        autogroup_kref_put(prev);
+}
+
+/* Allocates GFP_KERNEL, cannot be called under any spinlock */
+void sched_autogroup_create_attach(struct task_struct *p)
+{
+        struct autogroup *ag = autogroup_create();
+
+        autogroup_move_group(p, ag);
+        /* drop extra reference added by autogroup_create() */
+        autogroup_kref_put(ag);
+}
+EXPORT_SYMBOL(sched_autogroup_create_attach);
+
+/* Cannot be called under siglock.  Currently has no users */
+void sched_autogroup_detach(struct task_struct *p)
+{
+        autogroup_move_group(p, &autogroup_default);
+}
+EXPORT_SYMBOL(sched_autogroup_detach);
+
+void sched_autogroup_fork(struct signal_struct *sig)
+{
+        sig->autogroup = autogroup_task_get(current);
+}
+
+void sched_autogroup_exit(struct signal_struct *sig)
+{
+        autogroup_kref_put(sig->autogroup);
+}
+
+static int __init setup_autogroup(char *str)
+{
+        sysctl_sched_autogroup_enabled = 0;
+
+        return 1;
+}
+
+__setup("noautogroup", setup_autogroup);
+
+#ifdef CONFIG_PROC_FS
+
+int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice)
+{
+        static unsigned long next = INITIAL_JIFFIES;
+        struct autogroup *ag;
+        int err;
+
+        if (*nice < -20 || *nice > 19)
+                return -EINVAL;
+
+        err = security_task_setnice(current, *nice);
+        if (err)
+                return err;
+
+        if (*nice < 0 && !can_nice(current, *nice))
+                return -EPERM;
+
+        /* this is a heavy operation taking global locks.. */
+        if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
+                return -EAGAIN;
+
+        next = HZ / 10 + jiffies;
+        ag = autogroup_task_get(p);
+
+        down_write(&ag->lock);
+        err = sched_group_set_shares(ag->tg, prio_to_weight[*nice + 20]);
+        if (!err)
+                ag->nice = *nice;
+        up_write(&ag->lock);
+
+        autogroup_kref_put(ag);
+
+        return err;
+}
+
+void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
+{
+        struct autogroup *ag = autogroup_task_get(p);
+
+        if (!task_group_is_autogroup(ag->tg))
+                goto out;
+
+        down_read(&ag->lock);
+        seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
+        up_read(&ag->lock);
+
+out:
+        autogroup_kref_put(ag);
+}
+#endif /* CONFIG_PROC_FS */
+
+#ifdef CONFIG_SCHED_DEBUG
+static inline int autogroup_path(struct task_group *tg, char *buf, int buflen)
+{
+        if (!task_group_is_autogroup(tg))
+                return 0;
+
+        return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
+}
+#endif /* CONFIG_SCHED_DEBUG */
+
+#endif /* CONFIG_SCHED_AUTOGROUP */