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author | 2014-02-13 06:58:40 -0500 | |
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committer | 2014-02-13 06:58:40 -0500 | |
commit | 889ed9ceaa97bb02bf5d7349e24639f7fc5f4fa0 (patch) | |
tree | 82986b170db353226b40e26a0c8954645b676974 /kernel | |
parent | cpuset: use css_task_iter_start/next/end() instead of css_scan_tasks() (diff) | |
download | linux-889ed9ceaa97bb02bf5d7349e24639f7fc5f4fa0.tar.gz linux-889ed9ceaa97bb02bf5d7349e24639f7fc5f4fa0.tar.bz2 linux-889ed9ceaa97bb02bf5d7349e24639f7fc5f4fa0.zip |
cgroup: remove css_scan_tasks()
css_scan_tasks() doesn't have any user left. Remove it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/cgroup.c | 162 |
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) up_read(&css_set_rwsem); } -static inline int started_after_time(struct task_struct *t1, - struct timespec *time, - struct task_struct *t2) -{ - int start_diff = timespec_compare(&t1->start_time, time); - if (start_diff > 0) { - return 1; - } else if (start_diff < 0) { - return 0; - } else { - /* - * Arbitrarily, if two processes started at the same - * time, we'll say that the lower pointer value - * started first. Note that t2 may have exited by now - * so this may not be a valid pointer any longer, but - * that's fine - it still serves to distinguish - * between two tasks started (effectively) simultaneously. - */ - return t1 > t2; - } -} - -/* - * This function is a callback from heap_insert() and is used to order - * the heap. - * In this case we order the heap in descending task start time. - */ -static inline int started_after(void *p1, void *p2) -{ - struct task_struct *t1 = p1; - struct task_struct *t2 = p2; - return started_after_time(t1, &t2->start_time, t2); -} - -/** - * css_scan_tasks - iterate though all the tasks in a css - * @css: the css to iterate tasks of - * @test: optional test callback - * @process: process callback - * @data: data passed to @test and @process - * @heap: optional pre-allocated heap used for task iteration - * - * Iterate through all the tasks in @css, calling @test for each, and if it - * returns %true, call @process for it also. - * - * @test may be NULL, meaning always true (select all tasks), which - * effectively duplicates css_task_iter_{start,next,end}() but does not - * lock css_set_rwsem for the call to @process. - * - * It is guaranteed that @process will act on every task that is a member - * of @css for the duration of this call. This function may or may not - * call @process for tasks that exit or move to a different css during the - * call, or are forked or move into the css during the call. - * - * Note that @test may be called with locks held, and may in some - * situations be called multiple times for the same task, so it should be - * cheap. - * - * If @heap is non-NULL, a heap has been pre-allocated and will be used for - * heap operations (and its "gt" member will be overwritten), else a - * temporary heap will be used (allocation of which may cause this function - * to fail). - */ -int css_scan_tasks(struct cgroup_subsys_state *css, - bool (*test)(struct task_struct *, void *), - void (*process)(struct task_struct *, void *), - void *data, struct ptr_heap *heap) -{ - int retval, i; - struct css_task_iter it; - struct task_struct *p, *dropped; - /* Never dereference latest_task, since it's not refcounted */ - struct task_struct *latest_task = NULL; - struct ptr_heap tmp_heap; - struct timespec latest_time = { 0, 0 }; - - if (heap) { - /* The caller supplied our heap and pre-allocated its memory */ - heap->gt = &started_after; - } else { - /* We need to allocate our own heap memory */ - heap = &tmp_heap; - retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); - if (retval) - /* cannot allocate the heap */ - return retval; - } - - again: - /* - * Scan tasks in the css, using the @test callback to determine - * which are of interest, and invoking @process callback on the - * ones which need an update. Since we don't want to hold any - * locks during the task updates, gather tasks to be processed in a - * heap structure. The heap is sorted by descending task start - * time. If the statically-sized heap fills up, we overflow tasks - * that started later, and in future iterations only consider tasks - * that started after the latest task in the previous pass. This - * guarantees forward progress and that we don't miss any tasks. - */ - heap->size = 0; - css_task_iter_start(css, &it); - while ((p = css_task_iter_next(&it))) { - /* - * Only affect tasks that qualify per the caller's callback, - * if he provided one - */ - if (test && !test(p, data)) - continue; - /* - * Only process tasks that started after the last task - * we processed - */ - if (!started_after_time(p, &latest_time, latest_task)) - continue; - dropped = heap_insert(heap, p); - if (dropped == NULL) { - /* - * The new task was inserted; the heap wasn't - * previously full - */ - get_task_struct(p); - } else if (dropped != p) { - /* - * The new task was inserted, and pushed out a - * different task - */ - get_task_struct(p); - put_task_struct(dropped); - } - /* - * Else the new task was newer than anything already in - * the heap and wasn't inserted - */ - } - css_task_iter_end(&it); - - if (heap->size) { - for (i = 0; i < heap->size; i++) { - struct task_struct *q = heap->ptrs[i]; - if (i == 0) { - latest_time = q->start_time; - latest_task = q; - } - /* Process the task per the caller's callback */ - process(q, data); - put_task_struct(q); - } - /* - * If we had to process any tasks at all, scan again - * in case some of them were in the middle of forking - * children that didn't get processed. - * Not the most efficient way to do it, but it avoids - * having to take callback_mutex in the fork path - */ - goto again; - } - if (heap == &tmp_heap) - heap_free(&tmp_heap); - return 0; -} - /** * cgroup_trasnsfer_tasks - move tasks from one cgroup to another * @to: cgroup to which the tasks will be moved |