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-rw-r--r--kernel/cgroup.c162
1 files changed, 0 insertions, 162 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 89428b9d9933..05c0c23549f9 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2697,168 +2697,6 @@ void css_task_iter_end(struct css_task_iter *it)
2697 up_read(&css_set_rwsem); 2697 up_read(&css_set_rwsem);
2698} 2698}
2699 2699
2700static inline int started_after_time(struct task_struct *t1,
2701 struct timespec *time,
2702 struct task_struct *t2)
2703{
2704 int start_diff = timespec_compare(&t1->start_time, time);
2705 if (start_diff > 0) {
2706 return 1;
2707 } else if (start_diff < 0) {
2708 return 0;
2709 } else {
2710 /*
2711 * Arbitrarily, if two processes started at the same
2712 * time, we'll say that the lower pointer value
2713 * started first. Note that t2 may have exited by now
2714 * so this may not be a valid pointer any longer, but
2715 * that's fine - it still serves to distinguish
2716 * between two tasks started (effectively) simultaneously.
2717 */
2718 return t1 > t2;
2719 }
2720}
2721
2722/*
2723 * This function is a callback from heap_insert() and is used to order
2724 * the heap.
2725 * In this case we order the heap in descending task start time.
2726 */
2727static inline int started_after(void *p1, void *p2)
2728{
2729 struct task_struct *t1 = p1;
2730 struct task_struct *t2 = p2;
2731 return started_after_time(t1, &t2->start_time, t2);
2732}
2733
2734/**
2735 * css_scan_tasks - iterate though all the tasks in a css
2736 * @css: the css to iterate tasks of
2737 * @test: optional test callback
2738 * @process: process callback
2739 * @data: data passed to @test and @process
2740 * @heap: optional pre-allocated heap used for task iteration
2741 *
2742 * Iterate through all the tasks in @css, calling @test for each, and if it
2743 * returns %true, call @process for it also.
2744 *
2745 * @test may be NULL, meaning always true (select all tasks), which
2746 * effectively duplicates css_task_iter_{start,next,end}() but does not
2747 * lock css_set_rwsem for the call to @process.
2748 *
2749 * It is guaranteed that @process will act on every task that is a member
2750 * of @css for the duration of this call. This function may or may not
2751 * call @process for tasks that exit or move to a different css during the
2752 * call, or are forked or move into the css during the call.
2753 *
2754 * Note that @test may be called with locks held, and may in some
2755 * situations be called multiple times for the same task, so it should be
2756 * cheap.
2757 *
2758 * If @heap is non-NULL, a heap has been pre-allocated and will be used for
2759 * heap operations (and its "gt" member will be overwritten), else a
2760 * temporary heap will be used (allocation of which may cause this function
2761 * to fail).
2762 */
2763int css_scan_tasks(struct cgroup_subsys_state *css,
2764 bool (*test)(struct task_struct *, void *),
2765 void (*process)(struct task_struct *, void *),
2766 void *data, struct ptr_heap *heap)
2767{
2768 int retval, i;
2769 struct css_task_iter it;
2770 struct task_struct *p, *dropped;
2771 /* Never dereference latest_task, since it's not refcounted */
2772 struct task_struct *latest_task = NULL;
2773 struct ptr_heap tmp_heap;
2774 struct timespec latest_time = { 0, 0 };
2775
2776 if (heap) {
2777 /* The caller supplied our heap and pre-allocated its memory */
2778 heap->gt = &started_after;
2779 } else {
2780 /* We need to allocate our own heap memory */
2781 heap = &tmp_heap;
2782 retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
2783 if (retval)
2784 /* cannot allocate the heap */
2785 return retval;
2786 }
2787
2788 again:
2789 /*
2790 * Scan tasks in the css, using the @test callback to determine
2791 * which are of interest, and invoking @process callback on the
2792 * ones which need an update. Since we don't want to hold any
2793 * locks during the task updates, gather tasks to be processed in a
2794 * heap structure. The heap is sorted by descending task start
2795 * time. If the statically-sized heap fills up, we overflow tasks
2796 * that started later, and in future iterations only consider tasks
2797 * that started after the latest task in the previous pass. This
2798 * guarantees forward progress and that we don't miss any tasks.
2799 */
2800 heap->size = 0;
2801 css_task_iter_start(css, &it);
2802 while ((p = css_task_iter_next(&it))) {
2803 /*
2804 * Only affect tasks that qualify per the caller's callback,
2805 * if he provided one
2806 */
2807 if (test && !test(p, data))
2808 continue;
2809 /*
2810 * Only process tasks that started after the last task
2811 * we processed
2812 */
2813 if (!started_after_time(p, &latest_time, latest_task))
2814 continue;
2815 dropped = heap_insert(heap, p);
2816 if (dropped == NULL) {
2817 /*
2818 * The new task was inserted; the heap wasn't
2819 * previously full
2820 */
2821 get_task_struct(p);
2822 } else if (dropped != p) {
2823 /*
2824 * The new task was inserted, and pushed out a
2825 * different task
2826 */
2827 get_task_struct(p);
2828 put_task_struct(dropped);
2829 }
2830 /*
2831 * Else the new task was newer than anything already in
2832 * the heap and wasn't inserted
2833 */
2834 }
2835 css_task_iter_end(&it);
2836
2837 if (heap->size) {
2838 for (i = 0; i < heap->size; i++) {
2839 struct task_struct *q = heap->ptrs[i];
2840 if (i == 0) {
2841 latest_time = q->start_time;
2842 latest_task = q;
2843 }
2844 /* Process the task per the caller's callback */
2845 process(q, data);
2846 put_task_struct(q);
2847 }
2848 /*
2849 * If we had to process any tasks at all, scan again
2850 * in case some of them were in the middle of forking
2851 * children that didn't get processed.
2852 * Not the most efficient way to do it, but it avoids
2853 * having to take callback_mutex in the fork path
2854 */
2855 goto again;
2856 }
2857 if (heap == &tmp_heap)
2858 heap_free(&tmp_heap);
2859 return 0;
2860}
2861
2862/** 2700/**
2863 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another 2701 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
2864 * @to: cgroup to which the tasks will be moved 2702 * @to: cgroup to which the tasks will be moved